Search

Background Rifampicin lowers nevirapine plasma concentrations by inducing cytochrome P450. However, few data are available on this interaction during the lead-in period of nevirapine treatment. Methods Eighteen HIV-1/tuberculosis co-infected adults receiving rifampicin daily as part of anti-tuberculosis therapy were evenly randomized to nevirapine initiation by dose escalation (NVP200) or nevirapine initiation at 200 mg twice daily (NVP400). Subjects underwent 12 h intensive pharmacokinetic sampling on Days 7, 14 and 21 of nevirapine treatment. A minimum effective concentration (MEC) of 3000 ng/mL was used to interpret nevirapine concentrations 12 h after dosing (C12). Trial registration number: NCT00617643 (www.clinicaltrials.gov). Results Day 7 geometric mean nevirapine C12 [90% confidence interval (CI)] was 1504 (1127–2115) ng/mL and 3148 (2451–4687) ng/mL in the NVP200 and NVP400 arms, respectively (P < 0.01). Nevirapine C12 on Days 14 and 21 was similar. On Day 21, nevirapine concentration in 64% of patients was below the MEC. On Day 7, geometric mean area under the curve (AUC0–12) was lower in the NVP200 arm, 25 223 (90% CI, 21 978–29 695) ng·h/mL versus 43 195 (35 607–57 035) ng·h/mL in the NVP400 arm (P < 0.01). Similarly, on Day 14, nevirapine AUC0–12 was lower in the NVP200 arm 23 668 (18 253–32 218) ng·h/mL versus the NVP400 arm 44 918 (36 264–62 769) ng·h/mL (P = 0.03). Conclusions In co-treated patients, nevirapine concentrations were below the MEC during initiation with dose escalation. Nevirapine initiation at the maintenance dose of 200 mg twice daily is preferred. Sub-therapeutic nevirapine concentrations were common at Day 21 with either regimen. Evaluation of higher nevirapine maintenance doses may be considered. [ABSTRACT FROM PUBLISHER]

Background. We aimed to assess cardiac conduction safety of coadministration of the CYP3A4 inhibitor lopinavir/ritonavir (LPV/r) and the CYP3A4 substrate artemether-lumefantrine (AL) in HIV-positive Ugandans. Methods. Open-label safety study of HIVpositive adults administered single-dose AL (80/400 mg) alone or with LPV/r (400/100 mg). Cardiac function was monitored using continuous electrocardiograph (ECG). Results. Thirty-two patients were enrolled; 16 taking LPV/r -based ART and 16 ART naïve. All took single dose AL. No serious adverse events were observed. ECG parameters in milliseconds remained within normal limits. QTc measurements did not change significantly over 72 hours although were higher in LPV/r arm at 24 (424 versus 406; P = .02) and 72 hours (424 versus 408; P = .004) after AL intake. Conclusion. Coadministration of single dose of AL with LPV/r was safe; however, safety of six-dose AL regimen with LPV/r should be investigated. [ABSTRACT FROM AUTHOR]

The article presents a study which discusses the effect of pregnancy on steady-state nevirapine pharmacokinetics (PK). It mentions that the Ugandan pregnant women were tested who are receiving nevirapine-based antiretroviral therapy. The authors concluded that the exposure to nevirapine were reduced during the third trimester of pregnant Ugandan women and asserts that the long-term impact of intermittent supoptimal nevirapine concentrations during pregnancy is unknown.

Background: Levonorgestrel subdermal implants are preferred contraceptives with an expected failure rate of <1% over 5 years. We assessed the effect of efavirenz- or nevirapine-based antiretroviral therapy (ART) coadministration on levonorgestrel pharmacokinetics., Methods: This nonrandomized, parallel group, pharmacokinetic evaluation was conducted in three groups of human immunodeficiency virus-infected Ugandan women: ART-naive (n = 17), efavirenz-based ART (n = 20), and nevirapine-based ART (n = 20). Levonorgestrel implants were inserted at baseline in all women. Blood was collected at 1, 4, 12, 24, 36, and 48 weeks. The primary endpoint was week 24 levonorgestrel concentrations, compared between the ART-naive group and each ART group by geometric mean ratio (GMR) with 90% confidence interval (CI). Secondary endpoints included week 48 levonorgestrel concentrations and unintended pregnancies., Results: Week 24 geometric mean levonorgestrel concentrations were 528, 280, and 710 pg/mL in the ART-naive, efavirenz, and nevirapine groups, respectively (efavirenz: ART-naive GMR, 0.53; 90% CI, .50, .55 and nevirapine: ART-naive GMR, 1.35; 90% CI, 1.29, 1.43). Week 48 levonorgestrel concentrations were 580, 247, and 664 pg/mL in the ART-naive, efavirenz, and nevirapine groups, respectively (efavirenz: ART-naive GMR, 0.43; 90% CI, .42, .44 and nevirapine: ART-naive GMR, 1.14; 90% CI, 1.14, 1.16). Three pregnancies (3/20, 15%) occurred in the efavirenz group between weeks 36 and 48. No pregnancies occurred in the ART-naive or nevirapine groups., Conclusions: Within 1 year of combined use, levonorgestrel exposure was markedly reduced in participants who received efavirenz-based ART, accompanied by contraceptive failures. In contrast, nevirapine-based ART did not adversely affect levonorgestrel exposure or efficacy., Clinical Trials Registration: NCT01789879., (© The Author 2015. Published by Oxford University Press for the Infectious Diseases Society of America.)

Objectives: To investigate the effect of food on the steady-state pharmacokinetics of rilpivirine when administered as a fixed-dose combination tablet containing tenofovir disoproxil fumarate, emtricitabine plus rilpivirine (TDF/FTC/RPV) in HIV-1-infected Ugandan patients., Methods: This was an open-label, three-period, longitudinal pharmacokinetic study with patients serving as their own controls. Fifteen consenting and virologically suppressed HIV-1-infected adults were switched from an efavirenz-based regimen to TDF/FTC/RPV for 56 days. Enrolled patients underwent 24 h blood sampling with TDF/FTC/RPV dosing in the fasted state (day 42), with a low-fat meal (11 g of fat/353 kcal, day 49) and with a moderate-fat meal (19 g of fat/589 kcal, day 56; reference). A viral load assessment was performed on day 56., Results: Rilpivirine AUC0-24 was significantly decreased by 16% (geometric mean ratio, 90% CI: 0.84, 0.73-0.96) during administration in the fasted state when compared with AUC0-24 during administration with a moderate-fat meal. Similarly, rilpivirine C24 was significantly decreased by 21% (0.79, 0.65-0.97) in the fasted state compared with a moderate-fat meal. Pharmacokinetic parameters were unchanged during administration with a low-fat meal, except for C24, which was significantly increased by 15% (1.15, 1.01-1.31) when compared with the moderate-fat meal. Rilpivirine Cmax was similar under the three meal conditions. Virological suppression was unchanged at the end of the study., Conclusions: A food effect was observed for steady-state pharmacokinetic parameters of rilpivirine (AUC0-24 and C24) when TDF/FTC/RPV was administered in the fasted state compared with the moderate-fat meal. The TDF/FTC/RPV formulation can be administered with either a low-fat or moderate-fat meal., (© The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

Objective: To investigate the pharmacokinetics of artemether, dihydroartemisinin and lumefantrine during rifampicin intake and after stopping rifampicin., Study Design: An open-label, two-phase, longitudinal drug interaction study with patients serving as their own controls., Methods: We recruited HIV-1-seropositive Ugandan adults who were receiving rifampicin-based tuberculosis treatment and who did not have malaria. Pharmacokinetic sampling after six doses of artemether-lumefantrine was performed during rifampicin-based tuberculosis treatment (phase 1) and repeated at least 3 weeks after stopping rifampicin-based tuberculosis treatment (phase 2)., Results: Six and five patients completed phases 1 and 2, respectively. Median age and weight were 30 years and 64 kg. Artemether and dihydroartemisinin area under the concentration-time curve (AUC(0-12h)) were significantly lower by 89% [geometric mean ratio (GMR) 90% confidence interval (CI) 0.11, 0.05-0.26] and 85% (0.15, 0.10-0.23), respectively, during rifampicin-based treatment when compared to AUC(0-12h) after stopping rifampicin intake. Similarly, artemether and dihydroartemisinin C(max) were 83% (0.17, 0.08-0.39) and 78% (0.22, 0.15-0.33) lower, respectively, during rifampicin treatment. For artemether, mean (±SD) C(12) was 0.5(±1.0) and 5.9(±2.5) ng/ml in phases 1 and 2, respectively. Corresponding values for dihydroartemisinin (DHA) were 0.3(±0.4) and 4.7(±2.0) ng/ml, respectively. Day 8 lumefantrine concentration was significantly lower by 84% (GMR 90% CI 0.16, 0.09-0.27), and AUC(Day3-Day25) was significantly lower by 68% (GMR 90% CI 0.32, 0.21-0.49) during rifampicin-based treatment when compared to exposure values after stopping rifampicin., Conclusion: Pharmacokinetic parameters for artemether-lumefantrine were markedly lower during rifampicin-based tuberculosis treatment. Artemether-lumefantrine should not be co-administered with rifampicin.

Objectives: Co-administration of artemether/lumefantrine with antiretroviral therapy has potential for pharmacokinetic drug interactions. We investigated drug-drug interactions between artemether/lumefantrine and efavirenz or nevirapine., Methods: We performed a cross-over study in which HIV-infected adults received standard six-dose artemether/lumefantrine 80/480 mg before and at efavirenz or nevirapine steady state. Artemether, dihydroartemisinin, lumefantrine, efavirenz and nevirapine plasma concentrations were measured and compared., Results: Efavirenz significantly reduced artemether maximum concentration (C(max)) and plasma AUC (median 29 versus 12 ng/mL, P < 0.01, and 119 versus 25 ng · h/mL, P < 0.01), dihydroartemisinin C(max) and AUC (median 120 versus 26 ng/mL, P < 0.01, and 341 versus 84 ng · h/mL, P < 0.01), and lumefantrine C(max) and AUC (median 8737 versus 6331 ng/mL, P = 0.03, and 280 370 versus 124 381 ng · h/mL, P < 0.01). Nevirapine significantly reduced artemether C(max) and AUC (median 28 versus 11 ng/mL, P < 0.01, and 123 versus 34 ng · h/mL, P < 0.01) and dihydroartemisinin C(max) and AUC (median 107 versus 59 ng/mL, P < 0.01, and 364 versus 228 ng · h/mL, P < 0.01). Lumefantrine C(max) and AUC were non-significantly reduced by nevirapine. Artemether/lumefantrine reduced nevirapine C(max) and AUC (median 8620 versus 4958 ng/mL, P < 0.01, and 66 329 versus 35 728 ng · h/mL, P < 0.01), but did not affect efavirenz exposure., Conclusions: Co-administration of artemether/lumefantrine with efavirenz or nevirapine resulted in a reduction in artemether, dihydroartemisinin, lumefantrine and nevirapine exposure. These drug interactions may increase the risk of malaria treatment failure and development of resistance to artemether/lumefantrine and nevirapine. Clinical data from population pharmacokinetic and pharmacodynamic trials evaluating the impact of these drug interactions are urgently needed.

We investigated the effect of food on the steady-state pharmacokinetics of lopinavir and ritonavir in 12 Ugandan patients receiving lopinavir coformulated with ritonavir (LPV/r) tablets using a crossover design. Intensive pharmacokinetic sampling was performed 7 days apart after LPV/r dosing under moderate fat, high fat, and fasted meal conditions. Lopinavir and ritonavir concentrations were determined by liquid chromatography and tandem mass spectrometry. Compared with the fasted state, a high fat meal reduced lopinavir and ritonavir area under the curve by 14% and 29%, respectively. With a moderate fat meal, area under the curve for both drugs was similar to the fasted state.

Background: Treatment of HIV/malaria-coinfected patients with antiretroviral therapy (ART) and artemisinin-based combination therapy has potential for drug interactions. We investigated the pharmacokinetics of artemether, dihydroartemisinin and lumefantrine after administration of a single dose of 80/480 mg of artemether/lumefantrine to HIV-infected adults, taken with and without lopinavir/ritonavir., Methods: A two-arm parallel study of 13 HIV-infected ART-naive adults and 16 HIV-infected adults stable on 400/100 mg of lopinavir/ritonavir plus two nucleoside reverse transcriptase inhibitors (ClinicalTrials.gov, NCT 00619944). Each participant received a single dose of 80/480 mg of artemether/lumefantrine under continuous cardiac function monitoring. Plasma concentrations of artemether, dihydroartemisinin and lumefantrine were measured., Results: Co-administration of artemether/lumefantrine with lopinavir/ritonavir significantly reduced artemether maximum concentration (C(max)) and area under the concentration-time curve (AUC) [median (range): 112 (20-362) versus 56 (17-236) ng/mL, P = 0.03; and 264 (92-1129) versus 151 (38-606) ng · h/mL, P < 0.01]. Dihydroartemisinin C(max) and AUC were not affected [66 (10-111) versus 73 (31-224) ng/mL, P = 0.55; and 213 (68-343) versus 175 (118-262) ng · h/mL P = 0.27]. Lumefantrine C(max) and AUC increased during co-administration [2532 (1071-5957) versus 7097 (2396-9462) ng/mL, P < 0.01; and 41,119 (12,850-125,200) versus 199,678 (71,205-251,015) ng · h/mL, P < 0.01]., Conclusions: Co-administration of artemether/lumefantrine with lopinavir/ritonavir significantly increases lumefantrine exposure, but decreases artemether exposure. Population pharmacokinetic and pharmacodynamic trials will be highly valuable in evaluating the clinical significance of this interaction and determining whether dosage modifications are indicated.

Objectives: The aim of this study was to develop and validate a population pharmacokinetic model in order to describe ritonavir-boosted saquinavir concentrations dosed twice and once daily in human immunodeficiency virus (HIV)-infected patients from the UK, Uganda and Thailand and to identify factors that may influence saquinavir pharmacokinetics., Methods: Pharmacokinetic data from 10 clinical studies were combined. Non-linear mixed effects modelling (NONMEM version V) was applied to determine the saquinavir pharmacokinetic parameters, interindividual/interoccasion variability (IIV/IOV) and residual error. Various covariates potentially related to saquinavir pharmacokinetics were explored, and the final model was validated by means of 95% prediction interval and testing the predictive performance of the model with data not included in the model-building process., Results: Ninety-seven patients were included from the UK (n = 52), Uganda (n = 18) and Thailand (n = 27), contributing 347 saquinavir profiles (1-14 profiles per patient). A one-compartment model with zero-order absorption and lag-time best described the data with IIV/IOV on apparent oral clearance (CL/F) and volume of distribution (V/F) and with IIV on duration and absorption lag-time. The ritonavir area under the curve over the dosing interval was significantly associated with saquinavir CL/F and V/F. A typical patient from the UK had approximately 1.5- and 3-fold higher saquinavir CL/F compared with patients from Uganda (89.0 versus 49.8 L/h) and Thailand (89.0 versus 26.7 L/h), respectively., Conclusions: A model to characterize ritonavir-boosted saquinavir pharmacokinetics in HIV-infected adults has been developed and validated. The model could be used for dosage adaptation following therapeutic drug monitoring and to assess patients' suitability for once-daily boosted saquinavir therapy.

Background: We aimed to compare the steady-state pharmacokinetic parameters and tolerability of Triomune 40 (stavudine 40 mg, lamivudine 150 mg and nevirapine 200 mg) and branded formulations of these drugs in HIV-infected Ugandans., Methods: This includes a randomized, open-label, cross-over study of HIV-infected patients stable on therapy for 1 month. Patients were randomized to generic or branded formulation. Plasma pharmacokinetics were assessed after 1 month. The following day, alternate formulation was administered, and 1 month later, drug pharmacokinetics were re-assessed. Plasma pharmacokinetics were determined using HPLC-UV detection. Similarity between steady-state pharmacokinetic parameters was assessed using the US Food and Drug Administration standards for bioequivalency testing. Tolerability was assessed using questionnaires., Results: Sixteen (10 females) patients completed the study. Median (IQR) age, weight and CD4 count were 37 (33.7-40) years, 65 (63.4-66) kg and 292 (220.7-344.5) cells/mm(3), respectively. All patients received co-trimoxazole. The geometric mean ratio (90% CI) for stavudine, lamivudine and nevirapine was 0.92 (0.78-1.08), 1.11 (0.95-1.30) and 0.84 (0.64-1.11), respectively, for C(max), and 0.83 (0.70-0.97), 1.06 (0.94-1.20) and 0.88 (0.71-1.10), respectively, for AUC. Stavudine plasma concentrations were significantly lower for the generic formulation. Pharmacokinetic parameter inter-individual variability ranged from 29% to 99%. There were no differences in tolerability for the two formulations., Conclusions: Pharmacokinetic profiles of generic and branded drugs were similar. Differences particularly with regard to stavudine were demonstrated. Surveillance of the quality of generic antiretroviral drugs in the target populations is needed. Capacity building for pharmacokinetic research in resource-limited settings is a priority.