Search

Introduction: Prevention of mother to child transmission of HIV (PMTCT) is frequently challenged by irregular access to more effective anti-retroviral therapy. Nevirapine single dose (sdNVP), sdNVP+AZT+3TC for MTCT prophylaxis and NVP+ AZT+3TC for treatment and PMTCT were withdrawn due to low genetic resistance barrier and low efficacy. However current PMTCT lines in Mozambique include DTG+3TC+TDF, TDF+3TC+EFV, DTG +ABC+3TC, and AZT + NVP syrup prophylaxis for exposed babies. We assessed NVP hair and plasma concentrations and association with HIV-1RNA suppression among HIV+ ante-partum and post-partum women under PMTCT in Maputo, Mozambique., Methods: From December 2013 to November 2014, prospectively were enrolled 200 HIV+ ante-partum women on 200mg nevirapine and zidovudine 300 plus lamivudine 150mg twice daily at least with 3 months treatment and seen again at 24 weeks post-partum. Self-reported pill-taking adherence, NVP concentrations in hair, plasma, hemoglobin, CD4 cell count, HIV-1 RNA load was evaluated. NVP concentration in hair and plasma was analyzed as categorical quartile variable based on better data fit. NVP concentration was set between ≤3.77 ng/ml in plasma and ≤17,20 ng/mg in hair in quartile one to ≥5.36 ng/ml in plasma and ≥53.21 ng/mg in hair in quartile four. Logistic regression models for repeated measures were calculated. Following the World Health Organization (WHO) guidelines we set viral suppression at HIV-1RNA < 1000 c/mL. Outcome was HIV-1 RNA<1000 copies/ml. Predictor was NVP concentration in hair categorized in quartiles., Results: In total 369 person-visits (median of 1.85) were recorded. Self-reported adherence was 98% (IQR 97-100%) at ante-partum. In 25% person visits, NVP concentrations were within therapeutic levels (3.77 ng/ml to 5.35 ng/ml) in plasma and (17.20 ng/mg to 53.20 ng/mg) in hair. In 50% person visits NVP concentrations were above 5.36 ng/ml in plasm and 53.21 ng/mg in hair. HIV-1 RNA suppression was found in 34.7% of women with two viral loads, one at enrollment and another in post-partum. Odds of HIV-1 RNA suppression in quartile 4, was about 6 times higher than in quartile 1 (p-value = 0.006) for NVP hair concentration and 7 times for NVP plasma concentration (p-value = 0.012)., Conclusions: The study results alert for potential low efficacy of current PMTCT drug regimens in use in Mozambique. Affordable means for individual monitoring adherence, ART plasma and hair levels, drug resistant and HIV-1 RNA levels monitoring are recommended for prompt identification of inadequate drug regimens exposure patterns and adjust accordingly., Competing Interests: The authors have declared that no competing interests exist.

HIV-related stigma, lack of disclosure and social support are still hindrances to HIV testing, care, and prevention. We assessed the association of these social-psychological statuses with nevirapine (NVP) and efavirenz (EFV) plasma concentrations among HIV patients in Kenya. Blood samples were obtained from 254 and 312 consenting HIV patients on NVP- and EFV-based first-line antiretroviral therapy (ART), respectively, and a detailed structured questionnaire was administered. The ARV plasma concentration was measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). There were 68.1% and 65.4% of the patients on NVP and EFV, respectively, who did not feel guilty for being HIV positive. The disclosure rates were approximately 96.1% and 94.6% of patients on NVP and EFV, respectively. Approximately 85% and 78.2% of patients on NVP and EFV, respectively, received social support as much as needed. There were 54.3% and 14.2% compared to 31.7% and 4.5% patients on NVP and EFV, respectively, with supratherapeutic and suboptimal plasma concentrations. Multivariate quantile regression analysis showed that feeling guilty for being HIV positive was associated with increased 954 ng/mL NVP plasma concentrations (95% CI 192.7 to 2156.6; p = 0.014) but not associated with EFV plasma concentrations (adjusted β = 347.7, 95% CI = - 153.4 to 848.7; p = 0.173). Feeling worthless for being HIV positive was associated with increased NVP plasma concentrations (adjusted β = 852, 95% CI = 64.3 to 1639.7; p = 0.034) and not with EFV plasma concentrations (adjusted β = - 143.3, 95% CI = - 759.2 to 472.5; p = 0.647). Being certain of telling the primary sexual partner about HIV-positive status was associated with increased EFV plasma concentrations (adjusted β 363, 95% CI, 97.9 to 628.1; p = 0.007) but not with NVP plasma concentrations (adjusted β = 341.5, 95% CI = - 1357 to 2040; p = 0.692). Disclosing HIV status to neighbors was associated with increased NVP plasma concentrations (adjusted β = 1731, 95% CI = 376 to 3086; p = 0.012) but not with EFV plasma concentrations (adjusted β = - 251, 95% CI = - 1714.1 to 1212.1; p = 0.736). Obtaining transportation to the hospital whenever needed was associated with a reduction in NVP plasma concentrations (adjusted β = - 1143.3, 95% CI = - 1914.3 to - 372.4; p = 0.004) but not with EFV plasma concentrations (adjusted β = - 6.6, 95% CI = - 377.8 to 364.7; p = 0.972). HIV stigma, lack disclosure and inadequate social support are still experienced by HIV-infected patients in Kenya. A significant proportion of patients receiving the NVP-based regimen had supra- and subtherapeutic plasma concentrations compared to EFV. Social-psychological factors negatively impact adherence and are associated with increased NVP plasma concentration compared to EFV., (© 2021. The Author(s).)

Patients living with HIV in malarial endemic regions may experience clinically significant drug interaction between antiretroviral and antimalarial drugs. Effects of nevirapine (NVP), efavirenz (EFV) and lopinavir/ritonavir (LPVr) on lumefantrine (LM) therapeutic concentrations and toxicity were evaluated. In a four-arm parallel study design, the blood samples of 40 participants, treated with artemether/lumefantrine (AL), were analysed. Lumefantrine Cmax was increased by 32% (p = 0.012) and 325% (p < 0.0001) in the NVP and LPVr arms respectively but decreased by 62% (p < 0.0001) in the EFV-arm. AUC of LM was, respectively, increased by 50% (p = 0.27) and 328% (p < 0.0001) in the NVP and LPVr arms but decreased in the EFV-arm by 30% (p = 0.019). Median day 7 LM concentration was less than 280 ng/mL in EFV-arm (239 ng/mL) but higher in control (290 ng/mL), NVP (369 ng/mL, p = 0.004) and LPVr (1331 ng/mL, p < 0.0001) arms. There were no clinically relevant toxicities nor adverse events in both control and test arms. Artemether/lumefantrine is safe and effective for treatment of malaria in PLWHA taking NVP and LPVr based ART regimen but not EFV-based regimen., Competing Interests: Declaration of competing interest The Authors declare no conflicts of interest related to this work., (Copyright © 2020 The Authors. Production and hosting by Elsevier B.V. All rights reserved.)

Cytochrome P450 (CYP) is involved in the metabolism of nevirapine (NVP); especially, CYP2B6 has been known to be one of the main enzymes involved in NVP metabolism. The objective of this study was to investigate the effects of CYP2B6 variants on plasma concentrations of NVP by a systematic review and meta-analysis. A search for qualifying studies published until April 2020 was conducted using the EMBASE, PubMed, and Web of Science databases. The mean difference (MD) and 95% confidence intervals (CIs) were calculated. Data analysis was performed using R Studio (version 3.6) and Review Manager (version 5.3). In total, data from six studies involving 634 patients were analyzed in the systematic review and five studies in the meta-analysis. We found that carriers of the CYP2B6 516TT genotype had a 2.18 µg/mL higher NVP concentration than did the GG or GT (95% CI 1.28-3.08). In the respective comparisons of the three genotypes, it was found that the MD was 1.87 µg/mL between the TT and GT groups, 2.53 µg/mL between TT and GG, and 0.60 µg/mL between GT and GG. This meta-analysis confirmed that CYP2B6 polymorphisms was associated with plasma NVP concentrations. Therefore, CYP2B6 genotyping may be useful to predict the responses to NVP.

Central nervous system (CNS) HIV infection causes brain tissue inflammation and tissue deficit that contributes to neuroAIDS. This complication is escalated by the blood-brain barrier (BBB), which prevents easy access to antiretroviral drugs entering the CNS. In this study the aims were to investigate the BBB membrane penetration and brain localization patterns of Nevirapine (NVP) using Imaging Mass Spectrometry (MSI). Sprague-Dawley rats received an intraperitoneal dose of NVP (50 mg kg -1 ). Plasma and brain samples were harvested, and mass spectrometric methods were then applied to determine the pharmacokinetic properties and localization patterns of NVP in the brain. The pharmacokinetic parameters demonstrated a rapid bio-distribution of NVP in plasma and brain. The plasma C max was 6320 ng mL -1 and the brain C max was 1923 ng mL -1 , both at a T max of 0.25 h. MSI of coronal brain sections showed that NVP penetrated and localized in the brain regions implicated with the development of HIV associated neurodegeneration. NVP has great potential to combat neuroAIDS.

Introduction: To date, very little programmatic data has been published regarding serial antiretroviral (ARV) levels in infants exposed to maternal treatment and/or infant prophylaxis during the first months of life. Such data provide the opportunity to describe the proportion of infants exposed to virologically suppressive levels of ARVs and to gauge adherence to the prevention of mother-to-child transmission of HIV (PMTCT) programme., Methods: From August 2014 to January 2016, HIV-exposed infants born at Kalafong Provincial Tertiary Hospital in Pretoria, South Africa were enrolled as part of an observational cohort study. Plasma samples from HIV-exposed uninfected infants were obtained at birth, 6-weeks, 10-weeks and 14-weeks of age and quantitative efavirenz (EFV) and nevirapine (NVP) drug level testing performed using liquid chromatography-mass spectrometry, irrespective of maternal ARV regimen. Descriptive analysis of EFV and NVP levels in relation to self-reported maternal and infant ARV exposure was performed. EFV levels >500 ng/mL and NVP levels >100 ng/mL were reported based on studies suggesting that trough levels above these thresholds are associated with virological suppression and PMTCT respectively., Results: Among 66 infants exposed to maternal EFVin utero, 29 (44%) had virologically suppressive plasma EFV levels at birth, with a median level of 1665 ng/mL (IQR: 1094 to 3673). Among infants who were exclusively breastfed at 6-, 10- and 14 weeks, 13/48 (27%), 5/25 (25%) and 0/21 (0%) had virologically suppressive EFV levels. Among 64 infants whose mothers reported administering daily infant NVP at time of their 6-week HIV PCR test, only 45 (70%) had NVP levels above the minimum prophylactic trough level., Conclusions: During the first 10-weeks after delivery, a quarter of breastfed infants born to women on an EFV-containing treatment regimen maintained virologically suppressive EFV plasma levels. This finding highlights the importance of both careful monitoring of ARV side effects and repeat HIV PCR after the first few months of life among HIV-exposed uninfected infants. As 30% of infants had inadequate NVP plasma levels at 6-weeks of age, adherence counselling to caregivers regarding infant prophylaxis needs to be enhanced to further reduce mother-to-child transmission of HIV., (© 2019 The Authors. Journal of the International AIDS Society published by John Wiley & Sons Ltd on behalf of the International AIDS Society.)

Aims of the Study: Nevirapine has an exceptional record for long-term tolerability with few side effects in human immunodeficiency virus (HIV) combined antiretroviral therapy (cART). Owing to relatively frequent hypersensitivity reactions (HSR) (15&ndash;25%) in the first 3 months after treatment initiation (especially in patients with a high CD4 count (&gt;250/&micro;l in women, &gt;400/&micro;l in men)), it is being used less and less. However, the rate of adverse events is lower when patients are already under suppressive cART. We present the results of a single centre strategy to offer the switch to a nevirapine-containing regimen and evaluate the potential role nevirapine could play in current antiretroviral treatment., Methods: All adult HIV-positive patients starting nevirapine at our centre since 2010 were evaluated in this retrospective analysis. We examined the proportion of patients on cART containing nevirapine, as well as the number of starts and stops every 6 months. Nevirapine discontinuation rates were analysed by sex, age, hepatitis C virus (HCV) status, time on nevirapine, ethnicity, CD4 nadir as well as CD4 count, HIV-RNA and ART backbone at nevirapine start., Results: Since 2014, more than a third of our treated HIV patients have been on nevirapine-containing therapy, with a stable percentage in the following years; 277 patients starting nevirapine for the first time were analysed. Thirty-three percent (92/277) of these first nevirapine therapies were discontinued, with 16 cases (17%) resuming nevirapine later during follow-up. Of the patients who continued nevirapine for more than 90 days (n = 221), 80% maintained nevirapine until their last follow-up. The nevirapine stop rate after the first 90 days was 15-fold lower (5.4 per 100 patient years, 95% confidence interval [CI] 4.0&ndash;7.2) than in the first 90 days. Overall, nevirapine was used for a median of 2.9 years (interquartile range [IQR] 0.5&ndash;5.6). In HCV co-infected patients, the treatment stop rate was 4-fold higher than in HIV mono-infected patients, but this difference was mainly due to treatment interruptions caused by drug-drug interactions with intermittent HCV therapy. Six out of seven Asian patients experienced HSR (hepatotoxicity / skin rash). In a population with 74% 3TC/ABC backbone, 81% fully suppressed, median CD4 nadir 240/&micro;l (IQR 120&ndash;360) and median CD4 count at nevirapine start 590/&micro;l (IQR 400&ndash;840), both high CD4 nadir and high CD4 count at nevirapine start were associated with lower rather than higher discontinuation rates. In fully suppressed patients with high CD4 count at nevirapine start, high CD4 nadir was not a risk factor for HSR. Major reasons for the discontinuation of nevirapine were HSR (liver, skin rash) in 38 cases (41% of all discontinuations) followed by other adverse drug reactions (n = 17) and non-adherence (n = 14). In patients who stopped nevirapine after more than 90 days, the major cause was non-adherence or other adverse drug reaction (both n = 12)., Conclusions: In this study, two thirds of the patients continued nevirapine with favourable long-term tolerability and efficacy. Thus, this low-cost &ldquo;old drug&rdquo; may still represent a valid treatment switch option for maintenance therapy in selected patients with a fully suppressed viral load. However, further evaluation is needed. &nbsp.

Therapeutic drug monitoring (TDM) of antiretroviral drugs requires accurate and precise analysis of their trace amounts in plasma samples. Solid-phase extraction (SPE) coupled with dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) was introduced as a simple and sensitive method for extraction, pre-concentration and simultaneous determination of efavirenz (EFV), nelfinavir (NFV) and nevirapine (NVP) in human plasma and pharmaceutical formulations by using high performance liquid chromatography (HPLC) with UV detection. A response surface methodology (RSM) based on central composite design (CCD) was used for optimizing the main variables in the extraction procedure. Under the optimum experimental conditions, the calibration curves were linear in the range of 0.1-400 ng mL -1 with correlation coefficients from 0.9982 to 0.9997 and limits of detection (at S/N = 3) of 0.03 to 0.07 ng mL -1 . Moreover the intra-day and inter-day precision (RSD%) were in the range of 2.2-4.2% and 3.1-5.2%, respectively. The enrichment factors and relative recoveries of the anti-HIV drugs were 459-1507 and 93.7-105.4%. The method was successfully applied to the simultaneous determination of the trace amounts of the antiretroviral drugs in blood plasma and pharmaceutical formulations., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Clinical trials demonstrated intermittent preventive treatment in pregnancy with mefloquine (MQ) reduced malaria rates among pregnant women, yet an unexpected higher risk of mother-to-child transmission (MTCT) of HIV among HIV-positive women receiving MQ has also been observed. To determine if interactions between antiretroviral drugs (ARVs) and MQ could contribute to the increased MTCT observed in women receiving MQ, we performed a retrospective cross-sectional analysis of ARV plasma concentrations in peripheral blood (maternal plasma) and cord blood (cord plasma) collected at delivery from 186 mothers participating in a randomized clinical trial of MQ (n = 102) compared with placebo (n = 84) in Kenya. Plasma zidovudine (AZT), lamivudine (3TC), and nevirapine (NVP) concentrations were measured by high-performance liquid chromatography-tandem mass spectrometry. Although only 4% (7/186) reported not using these ARVs, AZT, 3TC, and NVP were all below the limit of detection in 44% of maternal plasma and 42% of cord plasma samples, and proportions were similar between the two study arms. Median concentrations of AZT and 3TC were not significantly lower in the MQ arm compared with the placebo arm for maternal plasma and cord plasma (p > .05). However, median NVP concentrations were significantly lower in the MQ study arm compared with the placebo study arm in both maternal plasma (1,597 ng/mL vs. 2,353 ng/mL, Mann-Whitney Rank Sum, p = .023) and cord plasma (2,038 ng/mL vs. 2,434 ng/mL, p = .048). Reduced NVP concentrations in maternal and cord plasma of women receiving MQ suggest MQ may affect NVP metabolism for both mother and infant. These results highlight the need to evaluate potential drug-drug interactions between candidate antimalarials and ARVs for use in pregnant women.

Objectives: We evaluated whether dried blood spots (DBS) are suitable to monitor combined ART when samples are collected in rural Tanzania and transported over a long distance to a specialized bioanalytical laboratory., Methods: Plasma and DBS samples were collected in Tanzania from study patients treated with nevirapine, efavirenz or lopinavir. In addition, plasma, whole blood and DBS samples were obtained from a cohort of HIV patients at the site of the bioanalytical laboratory in Switzerland. DBS samples were analysed using a fully automated LC-MS/MS method., Results: Comparison of DBS versus plasma concentrations of samples obtained from the bridging study in Switzerland indicated an acceptable bias only for nevirapine (18.4%), whereas for efavirenz and lopinavir a pronounced difference of -47.4% and -48.1% was found, respectively. Adjusting the DBS concentrations by the haematocrit and the fraction of drug bound to plasma proteins removed this bias [efavirenz +9.4% (-6.9% to +25.7%), lopinavir +2.2% (-20.0% to +24.2%)]. Storage and transportation of samples from Tanzania to Switzerland did not affect the good agreement between plasma and DBS for nevirapine [-2.9% (-34.7% to +29.0%)] and efavirenz [-9.6% (-42.9% to +23.8%)]. For lopinavir, however, adjusted DBS concentrations remained considerably below [-32.8% (-70.4% to +4.8%)] corresponding plasma concentrations due to decay of lopinavir in DBS obtained under field conditions., Conclusions: Our field study shows that the DBS technique is a suitable tool for therapeutic drug monitoring in resource-poor regions; however, sample stability remains an issue for certain analytes and therefore needs special consideration.

Nevirapine (NVP) is a non-nucleoside reverse transcriptase inhibitor (NNRTI) widely used in the treatment of human immunodeficiency virus type 1 (HIV-1) and is the first-choice NNRTI during pregnancy. NVP shows a sex dimorphic profile in humans with sex differences in bioavailability, biotransformation and toxicity. In this study, sex differences in NVP metabolism and inhibition of NVP metabolism by the antidepressant nortriptyline (NT) were evaluated using rats as experimental animals. NVP was administered orally to male and female rats and sex differences in plasma levels and pharmacokinetic parameters were analysed. NVP plasma levels were higher in female compared with male rats, and pharmacokinetic parameters such as maximum plasma concentration (C max ), time to C max (T max ), half-life (t 1/2 ) and area under the plasma concentration-time curve from the time of dosing to the last measurable concentration (AUC last ) showed ca. 4-, 5-, 7- and 22-fold higher values in female rats. In vitro experiments carried out with hepatic microsomes confirmed slower NVP metabolism in female rats, with a maximum velocity (V max ) 2-fold lower than in male hepatic microsomes. The major metabolite in both sexes was 12-hydroxynevirapine (12-OH-NVP), with the V max for this metabolite being 15-fold lower in female compared with male rat hepatic microsomes. Inhibition of NVP metabolism by NT was similar in both sexes, with statistically non-significant differences in 50% inhibitory concentration (IC 50 ) values. In summary, NVP is metabolised more slowly in female compared with male rats, but the inhibitory effect of NT is similar in both sexes., (Copyright © 2018 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.)

Background: Newborns of HIV-infected mothers are given daily doses of nevirapine to prevent HIV-1 acquisition. Infants born to mothers with TB should also receive TB preventive therapy. TB preventive regimens include isoniazid for 6 months or rifampicin plus isoniazid for 3 months (RH preventive therapy). The effect of concomitant RH preventive therapy on nevirapine concentrations in infants is unknown., Patients and Methods: Tshepiso was a prospective case-control cohort study of pregnant HIV-infected women with and without TB whose newborn infants received standard doses of nevirapine for HIV prophylaxis. Infants born to mothers with TB also received RH preventive therapy. Infant plasma nevirapine concentrations were measured at 1 and 6 weeks. The effects of RH preventive therapy on nevirapine disposition were investigated in a population pharmacokinetic model., Results: Of 164 infants undergoing pharmacokinetic sampling, 46 received RH preventive therapy. After adjusting for weight using allometric scaling, the model estimated a 33% reduction in nevirapine trough concentrations with RH preventive therapy compared with TB-unexposed infants not receiving concomitant rifampicin and a 30% decline in trough concentrations in a typical infant between day 7 and 35 post-partum., Conclusions: Rifampicin-based TB preventative treatment reduces nevirapine concentrations significantly in HIV-exposed infants. Although the nevirapine exposures required to prevent HIV acquisition in breastfeeding infants are undefined, given the potential risks associated with underdosing nevirapine in this setting, it is prudent to avoid rifampicin-based preventive therapy in HIV-exposed children receiving prophylactic nevirapine., (© The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

In the present study, a graphite electrode (GE) modified by conductive film (containing functionalized multi-walled carbon nanotubes (f-MWCNTs), poly methylene blue p(MB) and gold nanoparticles (AuNPs)) was introduced for determination of nevirapine (NVP) as an anti-HIV drug by applying the differential pulse anodic stripping voltammetry (DPASV) technique. Modification of the electrode was investigated by scanning electron microscopy (SEM) and impedance electrochemical spectroscopy (EIS). All electrochemical effective parameters on detection of NVP were optimized and the oxidation peak current of drug was used for its monitoring. The obtained results confirmed that the oxidation peak currents increased linearly by increasing in NVP concentrations in the range of 0.1-50 μM and a detection limit of 53 nM was achieved. The proposed sensor (AuNPs/p(MB)/f-MWCNTs/GE) was successfully applied for the determination of NVP in blood serum and pharmaceutical samples. It revealed the excellent stability, repeatability and reproducibility as well., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Treatment failure is a key challenge in the management of HIV-1 infection. We conducted a mixed-model survey of plasma nevirapine (NVP) concentrations (cNVP) and viral load in order to examine associations with treatment and adherence outcomes among Kenyan patients on prolonged antiretroviral therapy (ART). Blood plasma was collected at 1, 4 and 24 hours post-ART dosing from 58 subjects receiving NVP-containing ART and used to determine cNVP and viral load (VL). Median duration of treatment was 42 (range, 12-156) months, and 25 (43.1%) of the patients had virologic failure (VF). cNVP was significantly lower for VF than non- VF at 1hr (mean, 2,111ng/ml vs. 3,432ng/ml, p = 0.003) and at 4hr (mean 1,625ng/ml vs. 3,999ng/ml, p = 0.001) but not at 24hr post-ART dosing. Up to 53.4%, 24.1% and 22.4% of the subjects had good, fair and poor adherence respectively. cNVP levels peaked and were > = 3μg.ml at 4 hours in a majority of patients with good adherence and those without VF. Using a threshold of 3μg/ml for optimal therapeutic nevirapine level, 74% (43/58), 65.5% (38/58) and 86% (50/58) of all patients had sub-therapeutic cNVP at 1, 4 and 24 hours respectively. cNVP at 4 hours was associated with adherence (p = 0.05) and virologic VF (p = 0.002) in a chi-square test. These mean cNVP levels differed significantly in non-parametric tests between adherence categories at 1hr (p = 0.005) and 4hrs (p = 0.01) and between ART regimen categories at 1hr (p = 0.004) and 4hrs (p<0.0001). Moreover, cNVP levels correlated inversely with VL (p< = 0.006) and positively with adherence behavior. In multivariate tests, increased early peak NVP (cNVP4) was independently predictive of lower VL (p = 0.002), while delayed high NVP peak (cNVP24) was consistent with increased VL (p = 0.033). These data strongly assert the need to integrate plasma concentrations of NVP and that of other ART drugs into routine ART management of HIV-1 patients.

Background: Adequate exposure to antiretroviral drugs is necessary to achieve and sustain viral suppression. However, the target antiretroviral concentrations associated with long-term viral suppression have not been adequately defined in children. We assessed the relationship between plasma lopinavir or nevirapine concentrations and the risk of subsequent viremia in children initially suppressed on antiretroviral therapy., Methods: After an induction phase of antiretroviral treatment, 195 children with viral suppression (viral load ≤400 copies/mL) were randomized to continue a lopinavir/ritonavir-based regimen or to switch to a nevirapine-based regimen (together with lamivudine and stavudine). Viral load and lopinavir or nevirapine concentrations were measured at clinic visits 4, 8, 12, 16, 20, 24, 36, 52, 64 and 76 weeks post randomization. Cox multiple failure event models were used to estimate the effects of drug concentrations on the hazard of viremia (viral load >50 copies/mL) RESULTS:: At randomization, the median (interquartile range) age, CD4 T-Lymphocyte percentage, weight-for-age and weight-for-height z scores were 19 (16-24) months, 29% (23-37), -0.6 (-1.3 to 0.2) and -3.2 (-4.1 to -2.1), respectively. The proportion of children with viral load 51-400 copies/mL at randomization was 43%. The hazard of subsequent viremia during follow-up was increased for lopinavir concentrations <1 versus ≥1 mg/L [adjusted hazard ratio 0.62 (95% confidence interval, 0.40-0.94)] and for children with viral loads 51-400 copies/mL at randomization. Nevirapine concentrations were not significantly associated with subsequent viremia., Conclusions: Plasma lopinavir concentrations predicted viral outcomes in children receiving lopinavir-based antiretroviral therapy. Our findings support a minimum target concentration of ≥1 mg/L of lopinavir to ensure sustained viral suppression.

Aims: Nevirapine is the first non-nucleoside reverse-transcriptase inhibitor approved and is widely used in combination therapy to treat HIV-1 infection. The pharmacokinetics of nevirapine was extensively studied in various populations with a parametric approach. Hence, this study was aimed to determine population pharmacokinetic parameters in Malaysian HIV-infected patients with a non-parametric approach which allows detection of outliers or non-normal distribution contrary to the parametric approach., Methods: Nevirapine population pharmacokinetics was modelled with Pmetrics. A total of 708 observations from 112 patients were included in the model building and validation analysis. Evaluation of the model was based on a visual inspection of observed versus predicted (population and individual) concentrations and plots weighted residual error versus concentrations. Accuracy and robustness of the model were evaluated by visual predictive check (VPC). The median parameters' estimates obtained from the final model were used to predict individual nevirapine plasma area-under-curve (AUC) in the validation dataset. The Bland-Altman plot was used to compare the AUC predicted with trapezoidal AUC., Results: The median nevirapine clearance was of 2.92 L/h, the median rate of absorption was 2.55/h and the volume of distribution was 78.23 L. Nevirapine pharmacokinetics were best described by one-compartmental with first-order absorption model and a lag-time. Weighted residuals for the model selected were homogenously distributed over the concentration and time range. The developed model adequately estimated AUC., Conclusions: In conclusion, a model to describe the pharmacokinetics of nevirapine was developed. The developed model adequately describes nevirapine population pharmacokinetics in HIV-infected patients in Malaysia.

The present studies describe the systematic quality by design (QbD)-oriented development and validation of a simple, rapid, sensitive and cost-effective reversed-phase HPLC bioanalytical method for nevirapine in rat plasma. Chromatographic separation was carried out on a C18 column using isocratic 68:9:23% v/v elution of methanol, acetonitrile and water (pH 3, adjusted by orthophosphoric acid) at a flow rate of 1.0 mL/min using UV detection at 230 nm. A Box-Behnken design was applied for chromatographic method optimization taking mobile phase ratio, pH and flow rate as the critical method parameters (CMPs) from screening studies. Peak area, retention time, theoretical plates and peak tailing were measured as the critical analytical attributes (CAAs). Further, the bioanalytical liquid-liquid extraction process was optimized using an optimal design by selecting extraction time, centrifugation speed and temperature as the CMPs for percentage recovery of nevirapine as the CAA. The search for an optimum chromatographic solution was conducted through numerical desirability function. Validation studies performed as per the US Food and Drug Administration requirements revealed results within the acceptance limit. In a nutshell, the studies successfully demonstrate the utility of analytical QbD approach for the rational development of a bioanalytical method with enhanced chromatographic separation and recovery of nevirapine in rat plasma. Copyright © 2015 John Wiley & Sons, Ltd., (Copyright © 2015 John Wiley & Sons, Ltd.)

We investigated the influence of efavirenz (EFV)- or nevirapine (NVP)-based antiretroviral therapy (ART) on lumefantrine plasma exposure in HIV-malaria-coinfected patients and implication of pharmacogenetic variations. A total of 269 HIV patients with uncomplicated falciparum malaria on NVP-based ART (NVP-arm), EFV-based ART (EFV-arm) or not receiving ART (control-arm) were enrolled and treated with artemether-lumefantrine. Day-7 lumefantrine, baseline EFV and NVP plasma concentrations, and CYP2B6*6,*18, CYP3A4*1B, CYP3A5*3,*6,*7, ABCB1 c.3435C>T and ABCB1 c.4036A>G genotypes were determined. The median day-7 lumefantrine plasma concentration was significantly lower in the EFV-arm compared with that in NVP- and control-arm. High EFV plasma concentrations and CYP2B6*6/*6 genotype significantly correlated with low lumefantrine plasma concentrations and high rate of recurrent parasitemia. No significant effect of NVP-based ART on lumefantrine exposure was observed. In conclusion, owing to long-term CYP3A induction, EFV-based ART cotreatment significantly reduces lumefantrine plasma exposure leading to poor malaria treatment response, which is more pronounced in CYP2B6 slow metabolizers.

The extremely high prevalence of HIV/AIDS in sub-Saharan Africa and limitations of current antiretroviral medicines demand new tools to optimize therapy such as pharmacogenomics for person-to-person variations. African populations exhibit greater genetic diversity than other world populations, thus making it difficult to extrapolate findings from one population to another. Nevirapine, an antiretroviral medicine, displays large plasma concentration variability which adversely impacts therapeutic virological response. This study, therefore, aimed to identify sources of variability in nevirapine pharmacokinetics and pharmacodynamics, focusing on genetic variation in CYP2B6 and CYP1A2. Using a cross-sectional study design, 118 HIV-infected adult Zimbabwean patients on nevirapine-containing highly active antiretroviral therapy (HAART) were characterized for three key functional single nucleotide polymorphisms (SNPs), CYP2B6 c.516G>T (rs3745274), CYP2B6 c.983T>C (rs28399499), and CYP1A2 g.-163C>A (rs762551). We investigated whether genotypes at these loci were associated with nevirapine plasma concentration, a therapeutic biomarker, and CD4 cell count, a biomarker of disease progression. CYP2B6 and CYP1A2 were chosen as the candidate genes based on reports in literature, as well as their prominence in the metabolism of efavirenz, a drug in the same class with nevirapine. Nevirapine plasma concentration was determined using LC-MS/MS. The mean nevirapine concentration for CYP2B6 c.516T/T genotype differed significantly from that of 516G/G (p < 0.001) and 516G/T (p < 0.01) genotypes, respectively. There were also significant differences in mean nevirapine concentration between CYP2B6 c.983T > C genotypes (p = 0.04). Importantly, the CYP1A2 g.-163C>A SNP was significantly associated with the pharmacodynamics endpoint, the CD4 cell count (p = 0.012). Variant allele frequencies for the three SNPs observed in this Zimbabwean group were similar to other African population groups but different to observations among Caucasian and Asian populations. We conclude that CYP2B6 c.516G>T and CYP2B6 c.983T>C could be important sources of nevirapine pharmacokinetic variability that could be considered for dosage optimization, while CYP1A2 g.-163C>A seems to be associated with HIV disease progression. These inter- and intra-population pharmacokinetic and pharmacodynamics differences suggest that a single prescribed dosage may not be appropriate for the treatment of disease. Further research into a personalized nevirapine regimen is required.

Objectives: Lipid-based nutrient supplements (LNSs) are increasingly used in HIV programmes in resource-limited settings. However, the possible effects of LNSs on the plasma concentrations of antiretroviral drugs have not been assessed. Here, we aimed to assess the effects of LNSs on plasma efavirenz and nevirapine trough concentrations in Ethiopian adult HIV-infected patients., Methods: The effects of LNSs were studied in adults initiating antiretroviral therapy (ART) in a randomized trial. Patients with body mass index (BMI) > 17 kg/m(2) (n = 282) received daily supplementation of an LNS containing whey (LNS/w), an LNS containing soy (LNS/s) or no LNS. Trough plasma concentrations of efavirenz and nevirapine were measured at 1 and 2 months. Genotyping for 516 G>T and 983 T>C polymorphisms of the cytochrome P450 (CYP) 2B6 locus was performed. Multilevel linear mixed-effects models were used to assess the associations between LNS and plasma efavirenz and nevirapine concentrations., Results: In patients with BMI > 17 kg/m(2), nevirapine concentrations were lower in the LNS/w and LNS/s groups by a median of -2.3 μg/mL [interquartile range (IQR) -3.9; -0.9 μg/mL; P = 0.002] and -2.1 μg/mL (IQR -3.9; -0.9 μg/mL; P = 0.01), respectively, compared with the group not receiving supplements. There were no differences between groups with respect to efavirenz plasma concentrations. The CYP2B6 516 G>T polymorphism was associated with a 5 μg/mL higher plasma efavirenz concentration compared with the wild type (P < 0.0001), while it was not associated with plasma nevirapine concentrations., Conclusions: Intake of an LNS was associated with lower plasma nevirapine trough concentrations, indicating possible drug-LNS interactions. The clinical relevance of such reductions in nevirapine exposure is not clear. Plasma efavirenz concentration was not affected by the LNS., (© 2015 British HIV Association.)

The unbound drug concentration in plasma is usually considered the only active fraction; thus the binding of a drug to a protein limits its pharmacological actions. This is of special importance for those highly bound drugs. Therefore, binding studies can be of great utility for those drugs where relationship between free and total drug concentration is variable among patients, or it can be altered by some condition or disease, or even by interactions with other drugs. However, there is a lack of validation guidelines for the determination of unbound concentrations. Antiretroviral drugs (ARVs), protease inhibitors (PIs), efavirenz and nevirapine are highly bound to proteins. Here, we present a review on the overall methods for the study of unbound fractions of highly bound plasma protein ARVs. We also provide a critical evaluation of the methods applied, their differences and the main points to be controlled and validated., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Background: Adherence to an antiretroviral regimen is imperative for treatment success in both HIV infected adults and children. Likewise, adherence to antiretroviral prophylaxis is critical in HIV prevention. Studies on pediatric adherence are limited, particularly the prophylactic use of antiretroviral drugs and treatment adherence in very young infants. The HIV Prevention Trials Network (HPTN) 046 study (Clinical Trial Registration NCT00074412) determined the safety and efficacy of an extended regimen of nevirapine suspension in infants born to HIV-1 infected women for the prevention of vertical HIV transmission during breastfeeding. As per protocol, adherence to nevirapine prophylaxis was measured by maternal verbal reports. In addition, the pharmacy assessed the unused returned suspension. The aim of this sub-study was to determine the reliability of maternal verbal reports in measuring adherence to antiretroviral prophylaxis in infants in the first 6 weeks of life and evaluating the unused returned nevirapine as an alternative method of measuring adherence., Methods: Maternal verbal reports and pharmacy returns indicative of "missed < 2 doses" were evaluated against a plasma nevirapine concentration of >100 ng/ml in a subgroup of infants at 2, 5 and 6 weeks of age. Plasma nevirapine concentration of >100 ng/ml was used as a marker of adherence (10 times the in vitro IC50 against HIV)., Results: Adherence was 87.7% (maternal verbal report) and 71.3% (unused returned medication), as compared to 85.6% by plasma nevirapine concentration. Evaluated against plasma nevirapine concentration <100 ng/ml, the sensitivity and specificity of maternal verbal reports to detect a missed dose in the last 3 days were 75% and 78% (p = 0.03) respectively. Overall, among infants who were classified as adherent based on missed doses by maternal verbal reports and unused returned medication, 88.4% and 87.4% of infants attained a nevirapine concentration above 100 ng/ml respectively., Conclusion: Maternal verbal reports are a reliable measure of adherence to infant antiretroviral prophylaxis in the first 6 weeks of life and could be useful in assessing adherence to antiretroviral treatment in infants younger than 6 weeks. In the absence of resources or expertise to determine plasma drug concentration, we would recommend random assessments of unused returned medication.

Mother-to-child transmission (MTCT) of HIV-1 remains a global health problem. The World Health Organization (WHO) recommendations advise the administration of a once-daily, oral, prophylactic regimen of the nonnucleoside reverse transcriptase inhibitor nevirapine (NVP) from birth until 4 to 6 weeks of age for infants born to HIV-infected mothers in regions without access to safe and nutritionally adequate alternatives to breast milk. A critical factor driving the successful implementation of the WHO guidelines involves sustaining high adherence to the frequent dosing. With these challenges in mind, we have developed the first injectable, sustained-release NVP formulations with the goal of providing, for 6 weeks or longer, preventative plasma drug levels from a single subcutaneous administration at birth. The long-acting NVP consists of large (>50 μm), monodisperse NVP particles coated with biocompatible polymers that control the drug release kinetics. Two lead formulations exhibiting burst-free, sustained-release kinetics for up to 75 days in vitro were developed. Subsequent in vivo studies in rats demonstrated no toxicity related to the formulations. Rat plasma NVP concentrations were above the analytical assay's limit of quantification for up to 28 days. Pharmacokinetic analysis of the rat plasma NVP concentration-time data allowed absorption rate constants to be calculated. These data then were used to simulate infant NVP exposure from a single injected dose (<200 mg) of our long-acting formulations, demonstrating preliminary feasibility of the technology to maintain safe, preventative NVP plasma levels (0.2 to 3.0 μg ml(-1)) for 6 weeks or longer., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)

One of the most frequent comorbidities of HIV infection is depression, with a lifetime prevalence of 22 to 45%. Therefore, it was decided to study a potential pharmacokinetic interaction between the nonnucleoside reverse transcriptase inhibitor nevirapine (NVP) and the tricyclic antidepressant nortriptyline (NT). NVP and NT were administered to rats either orally, intraduodenally, or intravenously, and the changes in plasma levels and pharmacokinetic parameters were analyzed. Experiments with rat and human hepatic microsomes were carried out to evaluate the inhibitory effects of NT on NVP metabolism. NVP plasma concentrations were significantly higher when this drug was coadministered with NT. The maximum plasma concentrations of NVP were increased 2 to 5 times and the total plasma clearance was decreased 7-fold in the presence of NT. However, statistically significant differences in the pharmacokinetic parameters of NT in the absence and presence of NVP were not found. In vitro studies with rat and human hepatic microsomes confirmed the inhibition of NVP hepatic metabolism by NT in a concentration-dependent way, with the inhibition being more intense in the case of rat microsomes. In conclusion, a pharmacokinetic interaction between NVP and NT was detected. This interaction was a consequence of the inhibition of hepatic metabolism of NVP by NT. In vivo human studies are required to evaluate the effects of this interaction on the pharmacokinetics of NVP before it can be taken into account for patients receiving NVP., (Copyright © 2014, American Society for Microbiology. All Rights Reserved.)

Pregnant women bear the greatest burden of malaria-human immunodeficiency virus co-infection. Previous studies suggest that interaction with antiretroviral drugs may compromise antimalarial pharmacokinetics and treatment outcomes. We conducted a preliminary clinical study to assess quinine pharmacokinetics in Malian pregnant women with acute malaria who reported taking nevirapine-based antiretroviral therapy. Of seven women, six had stable concentrations of nevirapine in the plasma and one had none. Quinine concentrations were lower, and its metabolite 3-hydroxyquinine higher, in the six women with nevirapine than in the one without, and quinine concentrations were below the recommended therapeutic range in 50% of the women. This preliminary observation warrants further research to understand the impact of long-term antiretroviral therapy on the treatment of acute malaria.

Objective: To determine the trough and two hour plasma levels of nevirapine, stavudine, and lamivudine when administered in fixed dose combinations (FDC)., Design: Cross sectional., Setting: Tertiary care hospital in Northern India., Participants: 79 HIV-infected children receiving antiretroviral therapy with FDCs for more than month., Intervention: Two-point sampling (0 and 2 hours after the morning dose)., Outcome Measures: Plasma concentrations of all three drugs were simultaneously assayed by liquid chromatography/mass spectroscopy., Results: Majority (77%) of children were receiving fixed dose combination of stavudine, lamivudine, nevirapine in the ratio of 6:30:50 mg. The median (IQR) trough and 2-hour plasma levels (µg/mL) of nevirapine, stavudine and lamivudine were 5.2 (4.0, 6.3) and 7.9 (6.0, 9.7); 0.1 (0.06, 0.16) and 1.1 (0.59, 1.6); 0.1 (0.02, 0.2) and 2.5 (1.4, 3.1), respectively. Very few children had sub-therapeutic plasma drug levels of stavudine (2.5%), lamivudine (7.6%) and nevirapine (10%). Inadequate viral suppression at 6 months follow up was significantly associated with initial high viral load, low CD4 percentage at the time of enrolment in study, and lower doses of lamivudine and stavudine., Conclusions: The currently available generic pediatric fixed dose antiretroviral combinations in India provide adequate drug exposure in majority of children.

Objectives: Nevirapine is widely used for the treatment of HIV-1 infection; however, its chronic use has been associated with severe liver and skin toxicity. Women are at increased risk for these toxic events, but the reasons for the sex-related differences are unclear. Disparities in the biotransformation of nevirapine and the generation of toxic metabolites between men and women might be the underlying cause. The present work aimed to explore sex differences in nevirapine biotransformation as a potential factor in nevirapine-induced toxicity., Methods: All included subjects were adults who had been receiving 400 mg of nevirapine once daily for at least 1 month. Blood samples were collected and the levels of nevirapine and its phase I metabolites were quantified by HPLC. Anthropometric and clinical data, and nevirapine metabolite profiles, were assessed for sex-related differences., Results: A total of 52 patients were included (63% were men). Body weight was lower in women (P = 0.028) and female sex was associated with higher alkaline phosphatase (P = 0.036) and lactate dehydrogenase (P = 0.037) levels. The plasma concentrations of nevirapine (P = 0.030) and the metabolite 3-hydroxy-nevirapine (P = 0.035), as well as the proportions of the metabolites 12-hydroxy-nevirapine (P = 0.037) and 3-hydroxy-nevirapine (P = 0.001), were higher in women, when adjusted for body weight., Conclusions: There was a sex-dependent variation in nevirapine biotransformation, particularly in the generation of the 12-hydroxy-nevirapine and 3-hydroxy-nevirapine metabolites. These data are consistent with the sex-dependent formation of toxic reactive metabolites, which may contribute to the sex-dependent dimorphic profile of nevirapine toxicity.

A contrast between the analytical performance characteristics using gas chromatography-mass spectrometry (GC-MS) liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-ultraviolet (LC-UV) detection for the determination of the antiretroviral drug (ARV) nevirapine (NVP) in fortified human plasma after QuEChERS extraction has been made. Analytical performance characteristics, i.e. linearities, instrument detection limits (IDLs), limits of quantitation (LOQs), method detection limits (MDLs), % mean recoveries and the corresponding relative standard deviations (%RSDs) were estimated using techniques above. Using GC-MS, the correlation coefficients (r(2)) were ≥0.990, which were deemed acceptable linearities. The MDLs ranged between 11.1-29.8μg/L and 13.7-36.0μg/L using helium and hydrogen carrier gases respectively. The LOQs ranged between 16.5-66.7μg/L and 28.4-98.7μg/L using helium and hydrogen carrier gases respectively with a % mean recovery of 83% and %RSD of 4.6%. Using LC-MS and LC-UV, the correlation coefficients (r(2)) were ≥0.990. The MDLs were ranged between 3.14 and 47.1μg/L. The LOQs ranged between 2.85 and 90.0μg/L respectively. The MDLs using GC-MS, LC-MS and LC-UV were below the therapeutic range for NVP in human plasma is considered to be between 2300μg/L (Cmin) and 8000μg/L (Cmax). This study also demonstrated that helium can be substituted with hydrogen which is relatively cheaper and easily obtainable even by use of a generator., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Background & Objectives: Among patients with HIV-associated tuberculosis (TB), reduced plasma non-nucleoside reverse transcriptase inhibitors (NNRTI) concentrations during rifampicin (RMP) co-administration could lead to HIV treatment failure. This study was undertaken to examine the association between plasma nevirapine (NVP) and efavirenz (EFV) concentrations and virological outcomes in patients infected with HIV-1 and TB., Methods: This was a nested study undertaken in a clinical trial of patients with HIV-1 and TB, randomized to two different once-daily antiretroviral treatment (ART) regimens along with anti-TB treatment (ATT). Trough concentrations of plasma NVP and EFV were estimated at months 1 (during ATT and ART) and 6 months (ART only) by HPLC. Plasma HIV-1 RNA level >400 copies/ml or death within 6 months of ART were considered as unfavourable outcomes. Genotyping of CYP2B6 516G>T polymorphism was performed., Results: Twenty nine per cent of patients in NVP arm had an unfavourable outcome at 6 months compared to 9 per cent in EFV arm (P<0.08). The mean NVP and EFV levels estimated at 1 and 6 months did not significantly differ between favourable and unfavourable responders. Logistic regression analysis showed CYP2B6 516G>T polymorphism significantly associated with virologic outcome in patients receiving EFV-based regimen., Interpretation & Conclusions: Trough plasma concentrations of NVP and EFV did not show any association with response to ART in patients on ATT and once-daily ART. CYP2B6 516G>T polymorphism was associated with virologic outcome among patients on EFV.

Reasons for Performing the Study: Midazolam is used to control seizures in horses and to enhance muscle relaxation, but its pharmacokinetics are unknown., Objective: To determine the pharmacokinetics and sedative effects of midazolam in horses., Study Design: Blinded, randomised, crossover design., Methods: Midazolam was administered i.v. at either 0.05 or 0.1 mg/kg bwt to 6 horses on 2 occasions at least 7 days apart using a crossover design. Blood samples were collected before and at predetermined times through 24 h after administration. Serum midazolam concentrations were determined by a liquid chromatography tandem-mass spectrometry method. Heart and respiratory rates and indices of sedation, ataxia, and sensitivity to stimuli were recorded before and at predetermined times after midazolam administration., Results: Pharmacokinetic analysis was performed on samples from 5 horses in each group. Median total clearance was 10.6 ml/min/kg (range 6.1-15.2 ml/min/kg) and 10.4 ml/min/kg (range 8.4-17.6 ml/min/kg), and median volume of distribution at steady state was 2094 ml/kg (range 2076-2413 ml/kg) and 2822 ml/kg (range 2270-7064 ml/kg) after the 0.05 mg/kg and 0.1 mg/kg bwt doses, respectively. Median distribution half-life was 24 min (range 6-42 min) and 39 min (range 33.6-72 min) and median terminal half-life was 216 min (range 120-248 min) and 408 min (range 192-924 min) after the 0.05 mg/kg and 0.1 mg/kg bwt doses, respectively. Cardiorespiratory parameters and sedation scores did not change. Midazolam caused agitation, postural sway, weakness, and one horse became recumbent after the 0.1 mg/kg bwt dose., Conclusions: Midazolam produces ataxia and postural sway of short duration after i.v. administration to horses. Sedation was not evident after midazolam administration. Drug redistribution is likely the primary mechanism for the termination of effect., Potential Relevance: Midazolam produces muscle relaxation but not sedation in adult horses., (© 2013 EVJ Ltd.)

Objective: Nevirapine is an important component of highly active antiretroviral therapy used in the treatment of HIV infection. There is a considerable variation in the pharmacokinetics of nevirapine and this variation can impact the efficacy and toxicity of nevirapine. Although some of this variation can be attributed to environmental factors, the degree to which heritability influences nevirapine pharmacokinetics is unknown. This study aims to estimate how much variation in nevirapine pharmacokinetics is due to genetic factors and to investigate the contribution of selected polymorphisms to this variability., Methods: Two doses of immediate-release nevirapine were administered to European (n=11) and African American (n=6) participants recruited from the Research in Access to Care in the Homeless cohort. A repeated drug administration method was then used to determine the relative genetic contribution (r(GC)) to variability in nevirapine AUC(0-6 h). Nevirapine plasma levels were quantified using LC/MS/MS. Patients were also genotyped for selected polymorphisms in candidate genes that may influence nevirapine pharmacokinetics., Results: A significant r(GC) for nevirapine AUC(0-6 h) was found in Europeans (P=0.02) and African Americans (P=0.01). A trend toward higher nevirapine AUC(0-6 h) for the CYP2B6 516TT (rs3745274; Q172H) genotype was observed in European Americans (P=0.19)., Conclusion: This study demonstrates that there is a significant genetic component to variability in nevirapine pharmacokinetics. Although genetic variants such as CYP2B6 polymorphisms attributed to some of this variation, these data suggest that there may be additional genetic factors that influence nevirapine pharmacokinetics.

Background: Non-nucleoside reverse transcriptase inhibitor (NNRTI)-resistant mutants have been shown to emerge after interruption of suppressive NNRTI-based antiretroviral therapy (ART) using routine testing. The aim of this study was to quantify the risk of resistance by sensitive testing and correlate the detection of resistance with NNRTI concentrations after treatment interruption and virologic responses after treatment resumption., Methods: Resistance-associated mutations (RAMs) and NNRTI concentrations were studied in plasma from 132 patients who interrupted suppressive ART within SMART. RAMs were detected by Sanger sequencing, allele-specific PCR, and ultra-deep sequencing. NNRTI concentrations were measured by sensitive high-performance liquid chromatography., Results: Four weeks after NNRTI interruption, 19/31 (61.3%) and 34/39 (87.2%) patients showed measurable nevirapine (>0.25 ng/ml) or efavirenz (>5 ng/ml) concentrations, respectively. Median eight weeks after interruption, 22/131 (16.8%) patients showed ≥1 NNRTI-RAM, including eight patients with NNRTI-RAMs detected only by sensitive testing. The adjusted odds ratio (OR) of NNRTI-RAM detection was 7.62 (95% confidence interval [CI] 1.52, 38.30; p = 0.01) with nevirapine or efavirenz concentrations above vs. below the median measured in the study population. Staggered interruption, whereby nucleos(t)ide reverse transcriptase inhibitors (NRTIs) were continued for median nine days after NNRTI interruption, did not prevent NNRTI-RAMs, but increased detection of NRTI-RAMs (OR 4.25; 95% CI 1.02, 17.77; p = 0.03). After restarting NNRTI-based ART (n = 90), virologic suppression rates <400 copies/ml were 8/13 (61.5%) with NNRTI-RAMs, 7/11 (63.6%) with NRTI-RAMs only, and 51/59 (86.4%) without RAMs. The ORs of re-suppression were 0.18 (95% CI 0.03, 0.89) and 0.17 (95% CI 0.03, 1.15) for patients with NNRTI-RAMs or NRTI-RAMs only respectively vs. those without RAMs (p = 0.04)., Conclusions: Detection of resistant mutants in the rebound viremia after interruption of efavirenz- or nevirapine-based ART affects outcomes once these drugs are restarted. Further studies are needed to determine RAM persistence in untreated patients and impact on newer NNRTIs.

A selective and high throughput liquid chromatography-mass spectrometry method has been developed and validated for the simultaneous quantification of tenofovir (TFV), lamivudine (3TC) and nevirapine (NVP) in human plasma using emtricitabine (FTC) as internal standard (ISTD). Following solid phase extraction (SPE), the analytes and ISTD were run on Prontosil C18AQ column (100mm×4.6mm, 3μm) using an isocratic mobile phase consisting of 1mM ammonium acetate in water (pH 6.5±0.3):acetonitrile (50:50, v/v). The precursor and product ions of the drugs were monitored on a triple quadrupole instrument operated in the negative ionization mode. The method was validated over a concentration range of 2-500ng/mL for TFV and over a concentration range of 10-4000ng/mL for 3TC and NVP with relative recoveries ranging from 61 to 85%. The intra and inter batch precision (%CV) across four validation runs was less than 12.2%. The accuracy determined at four QC levels (LLOQ, LQC, MQC and HQC) was within ±8.5%, in terms of relative error., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Background: Adherence to antiretroviral drugs in the treatment of paediatric HIV infection is complicated because of many factors including stigma and drug intake logistics. It is therefore important to identify children with non-adherence in order to intervene before they become at risk of developing treatment failure or drug resistance. The aim of this study was to determine the level of adherence to antiretroviral therapy (ART), measured by caretaker report, medication return and nevirapine plasma concentration. In addition, the association between level of adherence and patient's immune status was compared across the three methods of measuring adherence., Methods: This was a descriptive cross-sectional study involving HIV infected children aged 2-14 years, on nevirapine- based antiretroviral treatment for at least six months, attending care and treatment clinic in three municipal hospitals in Dar- Es- Salaam City. Eligible patients and their accompanying caretakers were consecutively enrolled after obtaining written informed consent. Structured questionnaires were administered to caretakers to assess patient's adherence by caretaker report and medication return whereas a single blood sample for CD4 cell count/percent and determination of nevirapine plasma concentration was taken from patients on the day of assessment., Results: A total of 300 patients and accompanying caretakers were enrolled and the mean patient age (SD) was 8 (3) years. Caretakers' report and medication return showed good adherence (98% and 97%) respectively. However, the level of adherence assessed by nevirapine plasma concentration (85%) was significantly lower than caretaker report and medication return (p < 0.001). The agreement between nevirapine plasma concentration and medication return and between nevirapine plasma concentration and caretaker report was weak (k = 0. 131) (k = 0. 09) respectively. Nevirapine plasma concentration below 3 μg/ml was associated with immunosuppression (p = 0. 021) whereas medication return (>5% of prescribed doses) and caretaker reported missing more than one dose within 72 hours prior to interview were not associated with immunosuppression (p = 0. 474), (p = 0. 569) respectively., Conclusion: Lower adherence level observed using nevirapine plasma concentration and its association with immunological response supports the validity of the method and indicates that adherence data obtained from caretaker report and medication return may overestimate the true adherence in paediatric antiretroviral therapy.

Background: Although some studies show higher antiretroviral concentrations in women compared to men, data are limited. We conducted a cross-sectional study of HIV-positive women to determine if protease inhibitor (PI) and non-nucleoside reverse transcriptase inhibitor (NNRTI) C(min) and Cmax values were significantly different than historical general population (predominantly male) averages and to evaluate correlates of higher concentrations., Methods: HIV-positive women with virologic suppression (viral load < 50copies/mL) on their first antiretroviral regimen were enrolled. Timed blood samples for C(min) and Cmax were drawn weekly for 3 weeks. The ratio of each individual's median C(min) and Cmax to the published population mean values for their PI or NNRTI was calculated and assessed using Wilcoxon sign-rank. Intra- and inter-patient variability of antiretroviral drug levels was assessed using coefficient of variation and intra-class correlation. Linear regression was used to identify correlates of the square root-transformed C(min) and Cmax ratios., Results: Data from 82 women were analyzed. Their median age was 41 years (IQR=36-48) and duration of antiretrovirals was 20 months (IQR=9-45). Median antiretroviral C(min) and Cmax ratios were 1.21 (IQR=0.72-1.89, p=0.003) (highest ratios for nevirapine and lopinavir) and 0.82 (IQR=0.59-1.14, p=0.004), respectively. Nevirapine and efavirenz showed the least and unboosted atazanavir showed the most intra- and inter-patient variability. Higher CD4+ count correlated with higher C(min). No significant correlates for Cmax were found., Conclusions: Compared to historical control data, C(min) in the women enrolled was significantly higher whereas Cmax was significantly lower. Antiretroviral C(min) ratios were highly variable within and between participants. There were no clinically relevant correlates of drug concentrations., Trial Registration: NCT00433979.

A simple, rapid, and sensitive high performance liquid chromatographic method with UV detection has been developed and validated according to the FDA guidelines for the quantitation of zidovudine (ZDV), lamivudine (LMV), and nevirapine (NVR) in human plasma. The sample was prepared by simple liquid-liquid extraction. Chromatographic separation was carried out in a Hypersil BDS, C(18) column (250 mm × 4.6 mm; 5 µm particle size) with simple mobile phase composition of 0.1 M ammonium acetate buffer in 0.5% acetic acid, v/v and methanol (40:60, v/v) at a flow rate of 0.85 ml min(-1) where detector was set at 270 nm with a total run time of 10 min which is very short for simultaneous estimation of three analytes in plasma. The method was linear over the concentration range of 50-3000, 50-2000 and 10-3000 ng ml(-1) with lower limit of quantifications (LLOQ) of 50, 50, and 10 ng ml(-1) for ZDV, LMV, and NVR, respectively. Accuracy and precision values of both within-run and between-run obtained from six different sets of three quality control (QC) samples along with the LLOQ analyzed in separate occasions for all the analytes ranged from 94.47-99.71% and 0.298-3.507%, respectively. Extraction recovery of analytes in plasma samples was above 90.16%. In stability tests, all the analytes in human plasma were stable during storage and assay procedure. The developed and validated method was successfully applied to quantitative determination of the three analytes in plasma for pharmacokinetic study in 12 healthy human volunteers., (Copyright © 2012 John Wiley & Sons, Ltd.)

Nevirapine is one of the most extensively prescribed antiretrovirals worldwide. The present analyses used data and specimens from two prior studies to characterize and compare plasma nevirapine phase I metabolite profiles following a single 200-mg oral dose of nevirapine in 10 HIV-negative African Americans and a steady-state 200-mg twice-daily dose in 10 HIV-infected Cambodians. Nevirapine was assayed by high-performance liquid chromatography (HPLC). The 2-, 3-, 8- and 12-hydroxy and 4-carboxy metabolites of nevirapine were assayed by liquid chromatography-tandem mass spectrometry (LC/MS/MS). Pharmacokinetic parameters were calculated by noncompartmental analysis. The metabolic index for each metabolite was defined as the ratio of the metabolite area under the concentration-time curve (AUC) to the nevirapine AUC. Every metabolite concentration was much less than the corresponding nevirapine concentration. The predominant metabolite after single dose and at steady state was 12-hydroxynevirapine. From single dose to steady state, the metabolic index increased for 3-hydroxynevirapine (P < 0.01) but decreased for 2-hydroxynevirapine (P < 0.001). The 3-hydroxynevirapine metabolic index was correlated with nevirapine apparent clearance (P < 0.001). These findings are consistent with induction of CYP2B6 (3-hydroxy metabolite) and a possible inhibition of CYP3A (2-hydroxy metabolite), although these are preliminary data. There were no such changes in metabolic indexes for 12-hydroxynevirapine or 4-carboxynevirapine. Two subjects with the CYP2B6 *6*6 genetic polymorphism had metabolic indexes in the same range as other subjects. These results suggest that nevirapine metabolite profiles change over time under the influence of enzyme induction, enzyme inhibition, and host genetics. Further work is warranted to elucidate nevirapine biotransformation pathways and implications for drug efficacy and toxicity.

Background: Effective contraception has been widely promoted for HIV-positive women. However, there are limited data on the interactions between combined hormonal contraceptives and nonnucleoside reverse transcriptase inhibitors ., Methods: This study assessed the steady-state contraceptive effectiveness and safety of combined oral contraceptive (COC) containing 0.150 mg desogestrel /0.030 mg ethinyl estradiol with either nevirapine (NVP) or efavirenz (EFV) in 34 HIV-positive women. The targeted level for contraceptive effectiveness was endogenous progesterone level < 3.0 ng/mL. We measured NVP/EFV plasma concentrations 12 hours after administration (C12) with and without COC. The desired therapeutic levels were >3.1 mg/L for NVP and 1.0-4.0 mg/L for EFV, respectively., Results: All 18 subjects in the NVP group had serum progesterone <1.0 ng/mL. Four of 16 subjects (25%) in the EFV group had serum progesterone >1.0 ng/mL, including 3 subjects with >3.0 ng/mL (might indicate ovulation). The difference in progesterone levels between the 2 groups was statistically significant (P = 0.04). The median C12 of NVP increased insignificantly by 17% with COC; the median C12 of EFV decreased significantly (P = 0.02) by 22%. In 3 of 16 subjects (19%) in the EFV group, C12 of EFV dropped below 1.0 mg/L., Conclusions: In contrast to NVP, coadministrating desogestrel/ethinyl estradiol containing COC with EFV was associated with unfavorable progesterone and antiretroviral levels. Our results suggest that NVP may be superior to EFV when used with COC in HIV-positive women.

The non-nucleoside reverse transcriptase inhibitor nevirapine (NVP) is widely used for the treatment of human immunodeficiency virus type 1 (HIV-1), particularly in developing countries. Despite its therapeutic benefits, NVP has been associated with skin and liver injury in exposed patients. Although the mechanism of the tissue injury is not yet clear, it has been suggested that reactive metabolites of NVP may be involved. The detection of NVP mercapturate in the urine of patients undergoing standard antiretroviral chemotherapy indicates that NVP undergoes bioactivation in vivo. However, covalent binding of drug to protein in patients remains to be determined. In this study, we investigate the chemical basis of NVP protein adduct formation by using human serum albumin (HSA) and glutathione S-transferase pi (GSTP) as model proteins in vitro. In addition, HSA was isolated from serum samples of HIV-1 patients undergoing NVP therapy to measure NVP haptenation. Mass spectrometric analysis of 12-sulfoxyl-NVP-treated HSA revealed that the drug bound selectively to histidine (His146, His242, and His338) and a cysteine residue (Cys34). The reaction proceeds most likely by a concerted elimination-addition mechanism. This pathway was further confirmed by the observation of NVP-modified Cys47 in GSTP. Importantly, the same adduct (His146) was detected in HSA isolated from the blood of patients receiving NVP, providing direct evidence that NVP modifies protein in vivo, via the formation of a reactive metabolite.

A selective and sensitive high performance liquid chromatography-tandem mass spectrometry method has been developed and validated for simultaneous determination of zidovudine (ZDV), lamivudine (3TC) and nevirapine (NVP) in human plasma. After Solid phase extraction (SPE), analytes and ISTDs were run on Peerless Basic C18 column with an injection volume of 3μL and run time of 3.0min. An isocratic mobile phase of 0.1% formic acid in water:methanol (15:85, v/v) was used with positive mass spectrometric detection. The method was validated over a concentration range of 5-1500ng/mL for ZDV and 3TC and over the concentration range of 10-3000ng/mL for NVP. The intraday and interday precision and accuracy across four validation runs were ranged from 1.6 to 10.1% and 93.8 to 110.8% respectively., (Copyright © 2013 Elsevier B.V. All rights reserved.)

A fast and reliable high performance liquid chromatography (HPLC) method with UV diode array detection for simultaneous quantitative analysis of the anti-retroviral drugs, nevirapine (NVP) and efavirenz (EFV) and the anti-malarial, lumefantrine (LUM) in human plasma has been developed and validated. The sample preparation consisted of a plasma protein precipitation with 0.5% acetic acid acetonitrile solution containing the internal standard halofantrine (HALO) prior the LC-analysis. Chromatographic separation was carried out on a Acclaim Polar Advantage C(16), column (150 mm × 4.6 mm, particle size, 3 μm) using a gradient of mobile phase made of 0.01% TFA in 0.1M ammonium acetate (solvent A) and 0.1% TFA in acetonitrile (solvent B). The separation of NVP, EFV, LUM and HALO was achieved within 17 min at a flow rate of 1.0 mL/min and detections were initially performed at three wavelengths, 275 nm (NVP), 255 nm (EFV), and 300 nm (LUM). The method selectivity was demonstrated in six different human plasma batches. In addition, several concomitant drugs were analyzed under our experimental conditions and none of them co-eluted with EFV, NVP and LUM. This demonstrated that our method is highly selective. Calibration graphs plotted with seven concentrations in duplicate for each compound were linear between the selected ranges with a regression coefficient (R(2)) greater than 0.998. Absolute extraction recovery for NVP, EFV and LUM were 99%, 98.6 and 102%, respectively. Inter- and intra-day coefficients of variation for LUM, EFV and NVP were ≤10%. The lower limits of quantification were 0.125 μg/mL for LUM and 0.250 μg/mL for both EFV and NVP. Intra- and inter-assay relative standard deviation values were found to be less than 15% at the concentrations examined (0.125-10.0 μg/mL for LUM and 0.250-15.0 μg/mL for both EFV and NVP). The present method was successfully implemented in Tanzania and only one wavelength (255 nm) was used to measure samples of patients receiving either NVP or EFV in combination with LUM. The concentration found in human plasma samples for all three compounds were within the calibration range. This makes our method particularly applicable and useful to resource-limited settings., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Single-dose nevirapine for mothers and newborns at delivery is the simplest prevention strategy for vertical HIV-1 transmission and hence widely used in resource-constrained settings. HIV-1-positive mothers and newborns received single-dose nevirapine in a prevention of mother-to-child HIV-1 transmission (PMTCT) program in Uganda. In a pharmacokinetic investigation, breast milk and plasma samples of mothers and newborns were collected. The nonlinear mixed-effects modeling approach was suitable for analysis (average: 1.8 samples/matrix/individual). For describing the nevirapine pharmacokinetics in mothers and newborns, a 1-compartment model was demonstrated to be sufficient. The plasma-placenta transfer could be quantified, revealing a transfer fraction of 11% to 25% (with a significant influence of time span between maternal nevirapine intake and birth) and a high transfer rate constant from maternal drug administration. Interindividual variability was moderate between mothers and high between newborns. Simulations revealed that newborns born early (<1 hour) after maternal nevirapine intake would benefit from a 3-fold higher nevirapine dosage (6 mg/kg) after birth for analogous protective plasma concentrations over the first 2 weeks. In contrast, postnatal nevirapine dosage seemed to be dispensable for newborns born late (>24 hours) after maternal nevirapine intake. These dosing recommendations should be evaluated in prospective studies, including additional antiretroviral drugs in accordance with current PMTCT guidelines., (© The Author(s) 2013.)

Isoniazid preventive therapy (IPT) is recommended in patients on antiretroviral treatment. Isoniazid (INH) inhibits CYP3A4, which metabolises nevirapine (NVP). Administration of INH may cause higher NVP concentrations and toxicity. We studied the effect of INH on NVP concentrations in 21 patients randomised to either placebo (n = 13) or INH (n = 8) in an ongoing trial of IPT in patients on ART. INH was associated with a 24% increase in median NVP area under the plasma concentration-time curve for the 12 h dosing interval, which was not statistically significant (P = 0.66).

Background: Therapeutic drug monitoring (TDM) of antiretroviral drugs (ARVs) is used to improve the efficacy and safety of ARVs, but there is little interest for the systematic or random TDM of ARVs in the medical management of patients with acquired immune deficiency syndrome. This study aimed to evaluate a different approach and test the potential advantages of TDM as part of medical treatments when clinical problems are identified in human immunodeficiency virus-infected patients., Methods: The authors conducted a prospective, noncontrolled, cohort study on 544 human immunodeficiency virus-positive patients treated either with a protease inhibitor (PI), atazanavir/lopinavir, or with a nonnucleoside reverse transcriptase inhibitor (NNRTI), efavirenz/nevirapine. Patients who had virological failure, clinical signs of toxicity, or a risk of pharmacokinetic interactions were identified as having medication-related problems (MRPs), and they were scheduled for TDM of the PIs or NNRTIs. Cases with drug levels outside the range were subjected to intervention, and a second determination of plasma levels and viral load was scheduled to assess their response to the intervention., Results: Of the 521 treatment courses analyzed, 173 (32.4%) presented at least 1 MRP during the study. The TDM yielded abnormal results in 52.5% of the 198 identified MRP cases (95% CI: 45%-59%). The patients treated with PIs had an increased risk for having drug plasma levels that fell outside the normal range compared to those treated with NNRTIs (relative risk =1.36, 95% CI: 1.04-1.79). The TDM-guided interventions contributed to the resolution of 52.1% of the cases that involved treatment courses with MRPs and abnormal drug plasma levels., Conclusions: MRPs, including therapeutic failure, were common in the patients who were included in the study. A high proportion of the treatment courses involving such MRPs also presented abnormal plasma drug levels. The TDM-guided interventions are advantageous under these situations because they allow the continuation of treatments that would otherwise be substituted by more complex and costly alternatives.

Objectives: To investigate the potential of nevirapine 200 mg once-daily regimen and evaluate the influence of patient characteristics on nevirapine concentrations., Methods: This was a prospective, multicentre cohort study with 532 HIV-infected patients receiving nevirapine as a part of their initial antiretroviral therapy. Plasma samples were collected at trough or peak time at the end of week 2 (lead-in period) and week 4, 12, 24, 36, and 48 (steady-state period), and nevirapine concentrations were determined using a validated HPLC method. Potential influencing factors associated with nevirapine concentrations were evaluated using univariate and multivariate logistic regression., Results: A total of 2348 nevirapine plasma concentrations were collected, including 1510 trough and 838 peak values. The median nevirapine trough and peak concentration during the lead-in period were 4.26 µg/mL (IQR 3.05-5.61) and 5.07 µg/mL (IQR 3.92-6.44) respectively, which both exceeded the recommended thresholds of nevirapine plasma concentrations. Baseline hepatic function had a moderate effect on median nevirapine trough concentrations at week 2 (4.25 µg/mL v.s. 4.86 µg/mL, for ALT <1.5 × ULN and ≥ 1.5 × ULN, respectively, P = 0.045). No significant difference was observed in median nevirapine trough concentration between lead-in and steady-state periods in patients with baseline ALT and AST level ≥ 1.5 × ULN (P = 0.171, P = 0.769), which was different from the patients with ALT/AST level <1.5ULN. The median trough concentrations were significantly higher in HIV/HCV co-infected patients than those without HCV at week 48 (8.16 µg/mL v.s. 6.15 µg/mL, P = 0.004)., Conclusions: The 200 mg once-daily regimen of nevirapine might be comparable to twice-daily in plasma pharmacokinetics in Chinese population. Hepatic function prior to nevirapine treatment and HIV/HCV coinfection were significantly associated with nevirapine concentrations.

A high-performance liquid chromatography/positive ion electrospray tandem mass spectrometry method for the simultaneous quantification of lamivudine, stavudine and nevirapine was developed and validated in dried blood spot (DBS) cards. The analytes were separated using an isocratic mobile phase on a reverse phase column and analyzed by MS/MS in the MRM mode using the respective [M + H]⁺ ions, m/z 230-112 for lamivudine, m/z 225-127 for stavudine, m/z 267-226 for nevirapine, m/z 383-337 for zidovudine (IS). The lower limit of quantification was 1 ng/mL for both lamivudine and stavudine and 10 ng/mL for nevirapine. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The method was successfully applied to quantify them in a rat pharmacokinetic study in whole blood, plasma and DBS cards after a single oral co-administration at the dose of 10, 2 and 13 mg/kg for lamivudine, stavudine and nevirapine, respectively, to male Wistar rats. Following oral administration the pharmacokinetic results in all the matrices are in close agreement. Thus accomplishment of this method would facilitate the ease of collection of clinical samples on DBS cards for lamivudine, stavudine and nevirapine during human clinical trials and therapeutic drug monitoring., (Copyright © 2012 John Wiley & Sons, Ltd.)

A rapid, simple, sensitive and selective LC-MS/MS method has been developed and validated for quantification of the atorvastatin (AT) and niacin (NA) in 250 μL human plasma. The analytical procedure involves a liquid-liquid extraction method using nevirapine as an internal standard (IS). The chromatographic separation was achieved on a Hypurity Advance (4.6 × 50 mm, 5 µm) column using a mobile phase consisting of 0.1% formic acid buffer-acetonitrile (20:80, v/v) at flow rate of 0.8 mL/min. The API-4000 LC-MS/MS was operated in the multiple-reaction monitoring mode using electrospray ionization. The total run time of analysis was 3 min and elution of AT, NA and IS occurred at 1.06, 1.84 and 0.92 min, respectively. A detailed validation of the method was performed as per the US Food and Drug Administration guidelines and the standard curves found to be linear in the range of 0.10-30.0 ng/mL for AT and 20.2-6026 ng/mL for NA, with a coefficient of correlation of ≥ 0.99 for both the compounds. AT and NA were found to be stable in a battery of stability studies, viz. bench-top, autosampler, re-injection, wet-extract and repeated freeze-thaw cycles. The developed assay method was successfully applied to a pharmacokinetic study in humans., (Copyright © 2012 John Wiley & Sons, Ltd.)