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BackgroundAlthough super-boosted lopinavir/ritonavir (LPV/r; ratio 4:4 instead of 4:1) is recommended for infants living with HIV and receiving concomitant rifampicin, in clinical practice, many different LPV/r dosing strategies are applied due to poor availability of pediatric separate ritonavir formulations needed to superboost. We evaluated LPV pharmacokinetics in infants with HIV receiving LPV/r dosed according to local guidelines in various sub-Saharan African countries with or without rifampicin-based tuberculosis (TB) treatment.MethodsThis was a 2-arm pharmacokinetic substudy nested within the EMPIRICAL trial (#NCT03915366). Infants aged 1-12 months recruited into the main study were administered LPV/r according to local guidelines and drug availability either with or without rifampicin-based TB treatment; during rifampicin cotreatment, they received double-dosed (ratio 8:2) or semisuperboosted LPV/r (adding a ritonavir 100 mg crushed tablet to the evening LPV/r dose). Six blood samples were taken over 12 hours after intake of LPV/r.ResultsIn total, 14/16 included infants had evaluable pharmacokinetic curves; 9/14 had rifampicin cotreatment (5 received double-dosed and 4 semisuperboosted LPV/r). The median (IQR) age was 6.4 months (5.4-9.8), weight 6.0 kg (5.2-6.8), and 10/14 were male. Of those receiving rifampicin, 6/9 infants (67%) had LPV Ctrough

IntroductionManagement of concomitant use of ART and TB drugs is difficult because of the many drug-drug interactions (DDIs) between the medications. This systematic review provides an overview of the current state of knowledge about the pharmacokinetics (PK) of ART and TB treatment in children with HIV/TB co-infection, and identifies knowledge gaps.MethodsWe searched Embase and PubMed, and systematically searched abstract books of relevant conferences, following PRISMA guidelines. Studies not reporting PK parameters, investigating medicines that are not available any longer or not including children with HIV/TB co-infection were excluded. All studies were assessed for quality.ResultsIn total, 47 studies met the inclusion criteria. No dose adjustments are necessary for efavirenz during concomitant first-line TB treatment use, but intersubject PK variability was high, especially in children 4 weeks old as well as twice-daily dolutegravir (instead of once daily) in children older than 6 years. Exposure to some TB drugs (ethambutol and rifampicin) was reduced in the setting of HIV infection, regardless of ART use. Only limited PK data of second-line TB drugs with ART in children who are HIV infected have been published.ConclusionsWhereas integrase inhibitors seem favourable in older children, there are limited options for ART in young children (

BackgroundDarunavir 800 mg once (q24h) or 600 mg twice (q12h) daily combined with low-dose ritonavir is used to treat HIV-positive pregnant women. Decreased total darunavir exposure (17%-50%) has been reported during pregnancy, but limited data on unbound exposure are available.ObjectivesTo evaluate total and unbound darunavir exposures following standard darunavir/ritonavir dosing and to explore the value of potential optimized darunavir/ritonavir dosing regimens for HIV-positive pregnant women.Patients and methodsA population pharmacokinetic analysis was conducted based on data from 85 women. The final model was used to simulate total and unbound darunavir AUC0-τ and Ctrough during the third trimester of pregnancy, as well as to assess the probability of therapeutic exposure.ResultsSimulations predicted that total darunavir exposure (AUC0-τ) was 24% and 23% lower in pregnancy for standard q24h and q12h dosing, respectively. Unbound darunavir AUC0-τ was 5% and 8% lower compared with post-partum for standard q24h and q12h dosing, respectively. The probability of therapeutic exposure (unbound) during pregnancy was higher for standard q12h dosing (99%) than for q24h dosing (94%).ConclusionsThe standard q12h regimen resulted in maximal and higher rates of therapeutic exposure compared with standard q24h dosing. Darunavir/ritonavir 600/100 mg q12h should therefore be the preferred regimen during pregnancy unless (adherence) issues dictate q24h dosing. The value of alternative dosing regimens seems limited.

Background Darunavir is a potent HIV protease inhibitor with a high barrier to resistance. We conducted a nested pharmacokinetic sub-study within CHAPAS-4 to evaluate darunavir exposure in African children with HIV, taking once-daily darunavir/ritonavir for second-line treatment. Methods We used data from the CHAPAS-4 pharmacokinetic sub-study treating children with once-daily darunavir/ritonavir (600/100 mg if 14–24.9 kg and 800/100 mg if ≥25 kg) with either tenofovir alafenamide fumarate (TAF)/emtricitabine (FTC), abacavir/lamivudine or zidovudine/lamivudine. Steady-state pharmacokinetic sampling was done at 0, 1, 2, 4, 6, 8, 12 and 24 hours after observed darunavir/ritonavir intake. Non-compartmental and population pharmacokinetic analyses were used to describe the data and identify significant covariates. Reference adult pharmacokinetic data were used for comparison. We simulated the World Health Organization (WHO) recommended 600/100 mg darunavir/ritonavir dose for the 25–34.9 kg weight band. Results Data from 59 children with median age and weight 10.9 (range 3.8–14.7) years and 26.0 (14.5–47.0) kg, respectively, were available. A two-compartment disposition model with transit absorption compartments and weight-based allometric scaling of clearance and volume best described darunavir data. Our population achieved geometric mean (%CV) darunavir AUC0–24h, 94.3(50) mg·h/L and C max, 9.1(35) mg/L, above adult reference values and C trough, 1.5(111) mg/L, like adult values. The nucleoside reverse-transcriptase inhibitor backbone was not found to affect darunavir concentrations. Simulated WHO-recommended darunavir/ritonavir doses showed exposures equivalent to adults. Higher alpha-1-acid glycoprotein increased binding to darunavir and decreased apparent clearance of darunavir. Conclusions Darunavir exposures achieved in our trial are within safe range. Darunavir/ritonavir can safely be co-administered with TAF/FTC. Both WHO-recommended 600/100 mg and CHAPAS-4 800/100 mg darunavir/ritonavir doses for the 25–34.9 kg weight band offer favourable exposures. The choice between them can depend on tablet availability. [ABSTRACT FROM AUTHOR]

BackgroundReducing the dose of efavirenz can improve safety, reduce costs, and increase access for patients with HIV infection. According to the World Health Organization, a similar dosing strategy for all patient populations is desirable for universal roll-out; however, it remains unknown whether the 400 mg daily dose is adequate during pregnancy.MethodsWe developed a mechanistic population pharmacokinetic model using pooled data from women included in seven studies (1968 samples, 774 collected during pregnancy). Total and free efavirenz exposure (AUC24 and C12) were predicted for 400 (reduced) and 600 mg (standard) doses in both pregnant and non-pregnant women.ResultsUsing a 400 mg dose, the median efavirenz total AUC24 and C12 during the third trimester of pregnancy were 91 and 87% of values among non-pregnant women, respectively. Furthermore, the median free efavirenz C12 and AUC24 were predicted to increase during pregnancy by 11 and 15%, respectively.ConclusionsIt was predicted that reduced-dose efavirenz provides adequate exposure during pregnancy. These findings warrant prospective confirmation.

Small molecule inhibitors (SMIs) are increasingly being used in the treatment of non‐small cell lung cancer. To support pharmacokinetic research and clinical treatment monitoring, our aim was to develop and validate an ultra‐performance liquid chromatography–mass spectrometry (UPLC‐MS/MS) assay for quantification of eight SMIs: adagrasib, alectinib, brigatinib, capmatinib, crizotinib, lorlatinib, selpercatinib, and sotorasib. Development of the UPLC‐MS/MS assay was done by trying different columns and eluents to optimize peak shape. The assay was validated based on guidelines of the European Medicines Agency. Chromatographic separation was performed with a gradient elution using ammonium formate in water and methanol. Detection was performed using a triple quadrupole tandem mass spectrometer with electrospray ionization. Validation was performed in a range of 10–2500 μg/L for lorlatinib, 25–6250 μg/L for alectinib and crizotinib, 25–10,000 μg/L for capmatinib and selpercatinib, 50–12,500 μg/L for brigatinib, and 100–25,000 μg/L for adagrasib and sotorasib. Imprecision was <8.88% and inaccuracy was <12.5% for all compounds. Seven out of eight compounds were stable for 96 h at room temperature. Sotorasib was stable for 8 h at room temperature. A sensitive and reliable method has been developed to quantify eight SMIs with a single assay, enhancing efficacy and safety of targeted therapies. [ABSTRACT FROM AUTHOR]

We characterized population pharmacokinetics in 42 African children receiving once-daily 25 mg (14 to <20 kg) or 50 mg (>20 kg) dolutegravir. Coadministration with emtricitabine and tenofovir alafenamide reduced dolutegravir bioavailability by 19.6% (95% confidence interval: 8.13%–30.8%) compared with zidovudine or abacavir with lamivudine. Nevertheless, concentrations remained above efficacy targets, confirming current dosing recommendations. [ABSTRACT FROM AUTHOR]

Introduction: When protease inhibitor (PI)-based second-line ART fails, guidelines recommend drug resistance testing and individualized third-line treatment. However, PI-resistant viral strains are rare and drug resistance testing is costly. We investigated whether less costly PI-exposure testing can be used to select those patients who would benefit most from drug resistance testing. Methods: We performed a retrospective analysis of South African adults living with HIV experiencing failure of ritonavir-boosted-lopinavi (LPV/r)-based second-line ART for whom drug resistance testing results were available. We included patients who received plasma-based drug resistance testing at a central South African reference laboratory in 2017 and patients who received dried blood spots (DBS)-based drug resistance testing at a rural South African clinic between 2009 and 2017. PI-exposure testing was performed on remnant plasma or DBS using liquid chromatography mass spectrometry (LCMS). Additionally, a low-cost immunoassay was used on plasma. Population genotypic drug resistance testing of the pol region was performed on plasma and DBS using standard clinical protocols. Results: Samples from 544 patients (494 plasma samples and 50 DBS) were included. Median age was 41.0 years (IQR: 33.3 to 48.5) and 58.6% were women. Median HIV-RNA load was 4.9 log10 copies/mL (4.3 to 5.4). Prevalence of resistance to the NRTI-backbone was 70.6% (349/494) in plasma samples and 56.0% (28/50) in DBS. Major PI-resistance mutations conferring high-level resistance to LPV/r were observed in 26.7% (132/494) of plasma samples and 12% (6/50) of DBS. PI-exposure testing revealed undetectable LPV levels in 47.0% (232/494) of plasma samples and in 60.0% (30/50) of DBS. In pooled analysis of plasma and DBS samples, detectable LPV levels had a sensitivity of 90% (84% to 94%) and a negative predictive failure of 95% (91% to 97%) for the presence of major LPV/r resistance. Conclusions: PI-exposure testing revealed non-adherence in half of patients experiencing failure on second-line ART and accurately predicted the presence or absence of clinically relevant PI resistance. PI-exposure testing constitutes a novel screening strategy in patients with virological failure of ART that can differentiate between different underlying causes of therapy failure and may allow for more effective use of limited resources available for drug resistance testing. Keywords: antiretroviral treatment; treatment failure; HIV drug resistance; adherence; drug level testing; low- and middle-income countries, 1 | INTRODUCTION Antiretroviral treatment (ART) programmes are expanding rapidly to people living with HIV in low- and middle-income countries (LMIC) in an effort to control the HIV epidemic. First-line [...]

Introduction: HIV treating physicians in the Netherlands follow the guidelines of the Department of Health and Human Services (DHHS). Most of these recommended initial regimens are single-tablet regimens (STRs), which incur higher costs. By the end of 2017, generic NRTI backbones had become widely available, offering a potentially cheaper multi-tablet regimen. This study aimed to evaluate guideline compliance in people with HIV who started antiretroviral therapy (ART), the uptake of generic multi-tablet regimens (gMTRs), and associated medication costs. Methods: This retrospective cohort study used data from the Dutch HIV Monitoring Foundation to determine the proportion of treatment-naïve people entering care who initiated ART according to the DHHS and type of ART regimens prescribed between January 2016 and December 2020. We analyzed ART prescriptions, both at the national level and per individual HIV treatment centers. We calculated the monthly ART costs based on Dutch medicine prices listed on www.medicijnkosten.nl for each calendar year. Results: In 2016, an integrase inhibitor-containing regimen was initiated in 77.3% which increased to 87.8% in 2020. The compliance rate to DHHS-recommended initial regimens ranged from 82.8% in 2016 to 90.9% in 2020. Most patients received single-tablet regimens, 81.3% in 2016 to 60.3% in 2020. After the introduction the gMTRs showed a steady increase from 17.8% in 2018 to 37.8% in 2020. The cost of the first-line regimen per patient decreased by 22.9% in 2020 compared with 2017. The decrease was larger in centers where treatment-naïve individuals with HIV were preferentially initiated on a gMTR. Conclusions: There was a high compliance to the "DHHS-recommended initial regimens for most people with HIV" in the Netherlands. Most people who initiated ART received STRs, although the percentage of people who started on STRs gradually decreased over time. The use of gMTRs increased over time and was associated with lower medication costs. [ABSTRACT FROM AUTHOR]

Patients are often switched between generic formulations of the same drug, but in some cases generic interchangeability is questioned. For generic drugs to be approved, bioequivalence with the innovator drug should be demonstrated, but evidence of bioequivalence is not required in the intended patient population or relative to other approved generics. Aim: We aim to identify pathophysiological pharmacokinetic subpopulations for whom there is a difference in comparative bioavailability compared to a healthy population. Methods: We used simulated exposures from a nonparametric model of multiple generics and the originator gabapentin. Exposure was simulated for virtual populations with pharmacokinetic characteristics beyond those of healthy subjects with regard to rate of absorption, volume of distribution and reduced renal function. Virtual parallel design bioequivalence studies were performed using a random sample of 24 simulated subjects, with standard acceptance criteria. Results: Results indicated increased pharmacokinetic variability for patient populations with a lower rate of absorption or a reduced renal function, but no change in the average comparable bioavailability ratio. This increased variability results in a reduced likelihood of demonstrating bioequivalence. Observations were similar for comparisons between all different formulations, as well as between subjects who received the identical formulation in a repeated fashion. No relevant effect was observed for simulations with increased volume of distribution. Conclusion: Our simulations indicate that the reduced likelihood of demonstrating bioequivalence for subjects with altered pharmacokinetics is not influenced by a formulation switch, nor does the average comparable bioavailability ratio change, therefore these results support generic interchangeability and current approval requirements for generics. [ABSTRACT FROM AUTHOR]

Background Tacrolimus is an important immunosuppressive agent with high intra- and inter-individual pharmacokinetic variability and a narrow therapeutic index. As tacrolimus extensively accumulates in erythrocytes, hematocrit is a key factor in the interpretation of tacrolimus whole blood concentrations. However, as hematocrit values in pediatric kidney transplant patients are highly variable after kidney transplantation, translating whole blood concentration targets without taking hematocrit into consideration is theoretically incorrect. The aim of this study is to evaluate the potential impact of hematocrit correction on tacrolimus target exposure in pediatric kidney transplant patients. Methods Data were obtained from 36 pediatric kidney transplant patients. Two hundred fifty-five tacrolimus whole blood samples were available, together responsible for 36 area under the concentration-time curves (AUCs) and trough concentrations. First, hematocrit corrected concentrations were derived using a formula describing the relationship between whole blood concentrations, hematocrit, and plasma concentrations. Subsequently, target exposure was evaluated using the converted plasma target concentrations. Ultimately, differences in interpretation of target exposure were identified and evaluated. Results In total, 92% of our patients had lower hematocrit (median 0.29) than the reference value of adult kidney transplant patients. A different evaluation of target exposure for either trough level, AUC, or both was defined in 42% of our patients, when applying hematocrit corrected concentrations. Conclusion A critical role for hematocrit in therapeutic drug monitoring of tacrolimus in pediatric kidney transplant patients is suggested in this study. Therefore, we believe that hematocrit correction could be a step towards improvement of tacrolimus dose individualization., Author(s): Anne M. Schijvens [sup.1] , Fransje H. S. van Hesteren [sup.1] , Elisabeth A. M. Cornelissen [sup.1] , Charlotte M. H. H. T. Bootsma-Robroeks [sup.1] , Roger J. M. [...]