Clinical pharmacology quality assurance program: models for longitudinal analysis of antiretroviral proficiency testing for international laboratories

Single Doses of Pediatric Dolutegravir Dispersible Tablets in Neonates Support Multidosing: PETITE-Dolutegravir Study

BACKGROUND

Dolutegravir dispersible tablets (DTG-DTs) are approved for infants 4 weeks or older and ≥3 kg but their suitability for neonates remains unknown.

METHODS

PETITE-DTG is a phase I/II, open-label, single-center, 2-stage trial in South Africa to evaluate the pharmacokinetics (PK) and safety of DTG in term neonates of pregnant individuals receiving DTG-based therapy. In stage 1, neonates on standard antiretroviral prophylaxis received a single dose of 5 mg DTG-DT between ≥14 and <28 days of life (cohort 1A) or <14 days of life (cohort 1B), followed by PK and safety assessments. A population PK model was developed and multidose scenarios were simulated (DTG targets: geometric mean C tau > 0.67 µg/mL and C max < 17.0 µg/mL).

RESULTS

Sixteen neonates, 8 per cohort, completed stage 1. The median (range) birth weight was 3.1 (2.6-4.2) kg, and PK sampling was performed between 3 and 22 days of life. No grade 3 or higher adverse events were observed. DTG clearance was influenced by body weight and postnatal age. Simulations predicted that >10% of neonates would have a C max > 17.0 µg/mL with DTG once daily (q24) during the first 2 weeks of life. The administration of DTG every 48 hours (q48) from day 1-14 of life, followed by DTG every 24 hours through day 28, predicted a geometric mean C tau between 0.86 and 4.35 µg/mL; 98% with a C max < 17.0 µg/mL.

CONCLUSIONS

Owing to the slow postnatal DTG clearance after birth, a multidose strategy of 5 mg DTG-DT q48 for the first 2 weeks of life, followed by q24 through 28 days, was selected for assessment in stage 2.

HIV Pharmacology Data Repository: Setting the New Information-Sharing Standard for Clinical and Preclinical Pharmacokinetic Studies

Drug development approaches increasingly harness computational modeling to predict drug behavior. These in silico approaches, collectively termed "pharmacometrics", have significant value in deriving biological meaning from the analysis of pooled drug concentration vs. time (CvT) datasets. However, the field lacks standardization for pharmacokinetic data description, requiring expert annotation to enable aggregate mining and sharing. These limitations impede data sharing and preservation as mandated by current NIH policies. To this end, we propose a minimum information standard for pharmacokinetic studies composed of three categories (Intervention, System, and Concentration). We implement this standard in the development of a web-based database: the HIV Pharmacology Data Repository (HIV PDR). We describe our technical approach for creating the HIV PDR, the protocols we established for standardized data deposition, and the current content of the database. We also demonstrate the utility of the HIV PDR for pharmacometrics research through computational modeling of CvT data extracted from this new database. Based on these efforts, we propose the HIV PDR as a standard to preserve and share pharmacokinetic data generated through preclinical and clinical HIV research.

Pharmacokinetics of Generic Pediatric Dolutegravir Dispersible Tablet in Thai Young Children Living With HIV Weighing Below Twenty Kilograms

INTRODUCTION

Dolutegravir (DTG) dispersible tablet (DTG-DT) is a pediatric-friendly formulation. We aimed to describe the pharmacokinetics and virologic responses of generic DTG-DT in children weighing <20 kg.

METHODS

Children living with HIV-1 and <7 years of age weighing 6 to <20 kg were eligible. A generic 10-mg scored DTG-DT was administered to children using 3 weight bands (WB): WB1 (6 to <10 kg), WB2 (10 to <14 kg) and WB3 (14 to <20 kg), at doses of 20 mg (higher than World Health Organization recommendation of 15 mg), 20 mg and 25 mg, respectively. Steady-state intensive pharmacokinetics (PK) was performed in fasting condition with blood sampling at predose and 1, 2, 3, 4, 6 and 24 hours postdose. DTG PK parameters were estimated using a noncompartmental analysis, and DTG trough concentrations (C 24 ) and 24-hour area under the concentration-time curve were calculated. Comparisons were made with ODYSSEY and IMPAACT 2019. And 90% effective concentration of 0.32 mg/L was used as a reference individual DTG C 24 concentration.

RESULTS

From August 2021 to March 2023, 29 Thai children with a median (interquartile range) age of 3.2 (1.5-4.8) years were enrolled; 8 in WB1, 9 in WB2 and 12 in WB3. All children were treatment experienced and 59% had HIV RNA <200 copies/mL. Overall geometric mean (coefficient of variation percentage) DTG C 24 was 1.0 (46%) mg/L [WB1, 0.9 (53%); WB2, 0.9 (27%); WB3, 1.2 (51%)]. Geometric mean (coefficient of variation percentage) 24-hour area under the concentration-time curve was 83.2 (24%) mg h/L [WB1, 84.3 (31%); WB2, 76.9 (16%); WB3, 87.6 (25%)]. At weeks 24 and 48, 90% and 92% of participants had plasma HIV RNA <200 copies/mL.

CONCLUSIONS

Generic DTG-DT provided adequate drug exposure in children weighing 6 to <20 kg. The exploratory dose of DTG 20 mg for children weighing 6 to <10 kg showed similar PK parameters to World Health Organization doses in the other WB.

Population Pharmacokinetics of Pediatric Lopinavir/Ritonavir Oral Pellets in Children Living with HIV in Africa

Antiretroviral therapy for children living with HIV (CLHIV) under 3 years of age commonly includes lopinavir/ritonavir (LPV/r). However, the original liquid LPV/r formulation has taste and cold storage difficulties. To address these challenges, LPV/r oral pellets have been developed. These pellets can be mixed with milk or food for administration and do not require refrigeration. We developed the population pharmacokinetic (PK) model and assessed drug exposure of LPV/r oral pellets administered twice daily to CLHIV per World Health Organization (WHO) weight bands. The PK analysis included Kenyan and Ugandan children participating in the LIVING studies (NCT02346487) receiving LPV/r pellets (40/10 mg) and ABC/3TC (60/30 mg) dispersible tablets. Population PK models were developed for lopinavir (LPV) and ritonavir (RTV) to evaluate the impact of RTV on the oral clearance (CL/F) of LPV. The data obtained from the study were analyzed using nonlinear mixed-effects modeling approach. Data from 514 children, comprising a total of 2,998 plasma concentrations of LPV/r were included in the analysis. The LPV and RTV concentrations were accurately represented by a one-compartment model with first-order absorption (incorporating a lag-time) and elimination. Body weight influenced LPV and RTV PK parameters. The impact of RTV concentrations on the CL/F of LPV was characterized using a maximum effect model. Simulation-predicted target LPV exposures were achieved in children with this pellet formulation across the WHO weight bands. The LPV/r pellets dosed in accordance with WHO weight bands provide adequate LPV exposures in Kenyan and Ugandan children weighing 3.0 to 24.9 kg.

Paediatric abacavir-lamivudine fixed-dose dispersible tablets and ritonavir-boosted lopinavir granules in neonates exposed to HIV (PETITE study): an open-label, two-stage, single-arm, phase 1/2, pharmacokinetic and safety trial

BACKGROUND

Existing solid antiretroviral fixed-dose combination formulations are preferred over liquid formulations in children, but their suitability for neonates is unknown. We evaluated the pharmacokinetics and safety of paediatric abacavir-lamivudine fixed-dose dispersible tablets and ritonavir-boosted lopinavir granules in neonates.

METHODS

In this open-label, two-stage, single-arm, phase 1/2, pharmacokinetic and safety trial, generic abacavir- lamivudine (120:60 mg) double-scored dispersible tablets and lopinavir boosted with ritonavir (40:10 mg) granules were studied. Neonates exposed to HIV (≥37 weeks gestational age) of no more than 3 days of age with birthweights of 2000-4000 g were identified through routine care in a tertiary hospital in Cape Town, South Africa. In stage 1, the pharmacokinetics and safety of two single doses were assessed to select the multidose strategy for stage 2. Neonates received a single dose of abacavir-lamivudine (30:15 mg, a quarter of a tablet) and lopinavir boosted with ritonavir (40:10 mg - one sachet) orally between 3 days and 14 days of age, and a second dose of a quarter tablet of abacavir-lamivudine and lopinavir boosted with ritonavir (80:20 mg, two sachets) 10-14 days later in stage 1. The multidose strategy selected in stage 2 was a quarter of the abacavir-lamivudine (30:15 mg) fixed-dose dispersible tablet once per day and two sachets of the lopinavir boosted with ritonavir (80:20 mg) granules twice per day from birth to age 28 days. In both stages two intensive pharmacokinetic visits were done, one at less than 14 days of life (pharmacokinetics 1) and another 10-14 days later (pharmacokinetics 2). Safety visits were done 1-2 weeks after each pharmacokinetic visit. Primary objectives were to assess pharmacokinetics and safety of abacavir, lamivudine, and lopinavir. Pharmacokinetic endpoints were area under the concentration time curve (AUC), maximum concentration, and concentration at end of dosing interval in all participants with at least one evaluable pharmacokinetic visit. Safety endpoints included grade 3 or worse adverse events, and grade 3 or worse treatment-related adverse events, occurring between study drug initiation and end of study. This completed trial is registered with the Pan African Clinical Trials Registry (PACTR202007806554538).

FINDINGS

Between Aug 18, 2021, and Aug 18, 2022, 24 neonates were enrolled into the trial and received study drugs. Eight neonates completed stage 1, meeting interim pharmacokinetic and safety criteria. In stage 2, 16 neonates received study drugs. Geometric mean abacavir and lamivudine exposures (AUC0-24) were higher at 6-14 days (51·7 mg × h/L for abacavir and 17·2 mg × h/L for lamivudine) than at 19-24 days of age (25·0 mg × h/L and 11·3 mg × h/L), whereas they were similar for lopinavir over this period (AUC 0-12 58·5 mg × h/L vs 46·4 mg × h/L). Abacavir geometric mean AUC0-24 crossed the upper reference range at pharmacokinetics 1, but rapidly decreased. Lamivudine and lopinavir AUC0-tau were within range. No grade 2 or worse adverse events were related to study drugs. One neonate had a grade 1 prolonged corrected QT interval using the Fridericia method that spontaneously resolved.

INTERPRETATION

Abacavir-lamivudine dispersible tablets and ritonavir-boosted lopinavir granules in neonates were safe and provided drug exposures similar to those in young infants. Although further safety data are needed, this regimen presents a new option for HIV prevention and treatment from birth. Accelerating neonatal pharmacokinetic studies of novel antiretroviral therapies is essential for neonates to also benefit from state-of-the-art treatments.

FUNDING

Unitaid.

Cocaine regulates antiretroviral therapy CNS access through pregnane-x receptor-mediated drug transporter and metabolizing enzyme modulation at the blood brain barrier

BACKGROUND

Appropriate interactions between antiretroviral therapies (ART) and drug transporters and metabolizing enzymes at the blood brain barrier (BBB) are critical to ensure adequate dosing of the brain to achieve HIV suppression. These proteins are modulated by demographic and lifestyle factors, including substance use. While understudied, illicit substances share drug transport and metabolism pathways with ART, increasing the potential for adverse drug:drug interactions. This is particularly important when considering the brain as it is relatively undertreated compared to peripheral organs and is vulnerable to substance use-mediated damage.

METHODS

We used an in vitro model of the human BBB to determine the extravasation of three first-line ART drugs, emtricitabine (FTC), tenofovir (TFV), and dolutegravir (DTG), in the presence and absence of cocaine, which served as our illicit substance model. The impact of cocaine on BBB integrity and permeability, drug transporters, metabolizing enzymes, and their master transcriptional regulators were evaluated to determine the mechanisms by which substance use impacted ART central nervous system (CNS) availability.

RESULTS

We determined that cocaine had a selective impact on ART extravasation, where it increased FTC's ability to cross the BBB while decreasing TFV. DTG concentrations that passed the BBB were below quantifiable limits. Interestingly, the potent neuroinflammatory modulator, lipopolysaccharide, had no effect on ART transport, suggesting a specificity for cocaine. Unexpectedly, cocaine did not breach the BBB, as permeability to albumin and 4 kDa FITC-dextran, as well as tight junction proteins and adhesion molecules remained unchanged. Rather, cocaine selectively decreased the pregnane-x receptor (PXR), but not constitutive androstane receptor (CAR). Consequently, drug transporter expression and activity decreased in endothelial cells of the BBB, including p-glycoprotein (P-gp), breast cancer resistance protein (BCRP), and multidrug resistance-associated protein 4 (MRP4). Further, cytochrome P450 3A4 (CYP3A4) enzymatic activity increased following cocaine treatment that coincided with decreased expression. Finally, cocaine modulated adenylate kinases that are required to facilitate biotransformation of ART prodrugs to their phosphorylated, pharmacologically active counterparts.

CONCLUSION

Our findings indicate that additional considerations are needed in CNS HIV treatment strategies for people who use cocaine, as it may limit ART efficacy through regulation of drug transport and metabolizing pathways at the BBB.

Abacavir Drug Exposures in African Children Under 14 kg Using Pediatric Solid Fixed Dose Combinations According to World Health Organization Weight Bands

BACKGROUND

The pharmacokinetics of abacavir (ABC) in African children living with HIV (CLHIV) weighing <14 kg and receiving pediatric fixed dose combinations (FDC) according to WHO weight bands dosing are limited. An ABC population pharmacokinetic model was developed to evaluate ABC exposure across different World Health Organization (WHO) weight bands.

METHODS

Children enrolled in the LIVING study in Kenya and Uganda receiving ABC/lamivudine (3TC) dispersible tablets (60/30 mg) according to WHO weight bands. A population approach was used to determine the pharmacokinetic parameters. Monte Carlo simulations were conducted using an in silico population with demographic characteristics associated with African CLHIV. ABC exposures (AUC0-24) of 6.4-50.4 mg h/L were used as targets.

RESULTS

Plasma samples were obtained from 387 children. A 1-compartment model with allometric scaling of clearance (CL/F) and volume of distribution (V/F) according to body weight best characterized the pharmacokinetic data of ABC. The maturation of ABC CL/F was characterized using a sigmoidal Emax model dependent on postnatal age (50% of adult CL/F reached by 0.48 years of age). Exposures to ABC were within the target range for children weighing 6.0-24.9 kg, but children weighing 3-5.9 kg were predicted to be overexposed.

CONCLUSIONS

Lowering the ABC dosage to 30 mg twice daily or 60 mg once daily for children weighing 3-5.9 kg increased the proportion of children within the target and provided comparable exposures. Further clinical study is required to investigate clinical implications and safety of the proposed alternative ABC doses.

Cocaine Regulates Antiretroviral Therapy CNS Access Through Pregnane-X Receptor-Mediated Drug Transporter and Metabolizing Enzyme Modulation at the Blood Brain Barrier

Background

Appropriate interactions between antiretroviral therapies (ART) and drug transporters and metabolizing enzymes at the blood brain barrier (BBB) are critical to ensure adequate dosing of the brain to achieve HIV suppression. These proteins are modulated by demographic and lifestyle factors, including substance use. While understudied, illicit substances share drug transport and metabolism pathways with ART, increasing the potential for adverse drug:drug interactions. This is particularly important when considering the brain as it is relatively undertreated compared to peripheral organs and is vulnerable to substance use-mediated damage.

Methods

We used an in vitro model of the human BBB to determine the extravasation of three first-line ART drugs, emtricitabine (FTC), tenofovir (TFV), and dolutegravir (DTG), in the presence and absence of cocaine, which served as our illicit substance model. The impact of cocaine on BBB integrity and permeability, drug transporters, metabolizing enzymes, and their master transcriptional regulators were evaluated to determine the mechanisms by which substance use impacted ART central nervous system (CNS) availability.

Results

We determined that cocaine had a selective impact on ART extravasation, where it increased FTC's ability to cross the BBB while decreasing TFV. DTG concentrations that passed the BBB were below quantifiable limits. Interestingly, the potent neuroinflammatory modulator, lipopolysaccharide, had no effect on ART transport, suggesting a specificity for cocaine. Unexpectedly, cocaine did not breach the BBB, as permeability to albumin and tight junction proteins and adhesion molecules remained unchanged. Rather, cocaine selectively decreased the pregnane-x receptor (PXR), but not constitutive androstane receptor (CAR). Consequently, drug transporter expression and activity decreased in endothelial cells of the BBB, including p-glycoprotein (P-gp), breast cancer resistance protein (BCRP), and multidrug resistance-associated protein 4 (MRP4). Further, cytochrome P450 3A4 (CYP3A4) enzymatic activity increased following cocaine treatment that coincided with decreased expression. Finally, cocaine modulated adenylate kinases are required to facilitate biotransformation of ART prodrugs to their phosphorylated, pharmacologically active counterparts.

Conclusion

Our findings indicate that additional considerations are needed in CNS HIV treatment strategies for people who use cocaine, as it may limit ART efficacy through regulation of drug transport and metabolizing pathways at the BBB.

Pharmacokinetics and Safety of the Abacavir/Lamivudine/Lopinavir/Ritonavir Fixed-Dose Granule Formulation (4-in-1) in Neonates: PETITE Study

BACKGROUND

Antiretroviral options for neonates (younger than 28 days) should be expanded. We evaluated the pharmacokinetics, safety, and acceptability of the "4-in-1" fixed-dose pediatric granule formulation of abacavir/lamivudine/lopinavir/ritonavir (30/15/40/10 mg) in neonates.

METHODS

The PETITE study is an ongoing phase I/II, open-label, single-arm, 2-stage trial conducted in South Africa. In stage 1, term neonates exposed to HIV on standard antiretroviral prophylaxis (nevirapine ± zidovudine) received single dose(s) of the 4-in-1 formulation, followed by intensive pharmacokinetic sampling and safety assessments. At each PK visit, blood was drawn after an observed dose at 1, 2, 4, 8, and 12 hours postdose. In this study, we have reported the planned interim pharmacokinetic and safety analysis after completion of the single-dose administration.

RESULTS

Sixteen neonates, with a median (range) birth weight of 3130 g (2790-3590 g), completed 24 pharmacokinetic visits. The 4-in-1 formulation imposed relatively high doses of abacavir [8.6 mg/kg (6.6-11.4)] and lamivudine [4.3 mg/kg (3.3-5.7)] but lower doses of lopinavir [11.5 mg/kg (8.8-15.2)]. The geometric means (GM, 90% CI) AUC0-12 of abacavir, lamivudine, and lopinavir were 29.87 (26.29-33.93), 12.61 (10.72-14.83), and 3.49 (2.13-5.72) µg.h/mL, respectively. Lopinavir GM AUC0-12 was below the predefined target (20-100 µg.h/mL), and ritonavir concentrations were only detectable in 4 of the 120 (3%) samples. No adverse events were related to study drugs. No neonate had difficulty swallowing the 4-in-1 formulation.

CONCLUSIONS

The high doses of abacavir and lamivudine (in mg/kg) and AUCs were safe, and the formulation was well tolerated; however, lopinavir/ritonavir exposures were extremely low, preventing its use in neonates use in neonates. Alternative pediatric solid antiretroviral formulations must be studied in neonates.

Pharmacokinetics and Safety of Zidovudine, Lamivudine, and Lopinavir/Ritonavir in HIV-infected Children With Severe Acute Malnutrition in Sub-Saharan Africa: IMPAACT Protocol P1092

BACKGROUND

Severe acute malnutrition (SAM) may alter the pharmacokinetics (PK), efficacy, and safety of antiretroviral therapy. The phase IV study, IMPAACT P1092, compared PK, safety, and tolerability of zidovudine (ZDV), lamivudine (3TC), and lopinavir/ritonavir (LPV/r) in children with and without SAM.

MATERIALS AND METHODS

Children living with HIV 6 to <36 months of age with or without World Health Organization (WHO)-defined SAM received ZDV, 3TC, and LPV/r syrup for 48 weeks according to WHO weight band dosing. Intensive PK sampling was performed at weeks 1, 12, and 24. Plasma drug concentrations were measured using liquid chromatography tandem mass spectrometry. Steady-state mean area under the curve (AUC0-12h) and clearance (CL/F) for each drug were compared. Grade ≥3 adverse events were compared between cohorts.

RESULTS

Fifty-two children were enrolled across 5 sites in Africa with 44% (23/52) female, median age 19 months (Q1, Q3: 13, 25). Twenty-five children had SAM with entry median weight-for-height Z-score (WHZ) -3.4 (IQR -4.0, -3.0) and 27 non-SAM had median WHZ -1.0 (IQR -1.8, -0.1). No significant differences in mean AUC0-12h or CL/F were observed (P ≥ 0.09) except for lower 3TC AUC0-12h (GMR, 0.60; 95% CI, 0.4-1.0; P = 0.047) at week 12, higher ZDV AUC0-12h (GMR, 1.52; 1.2-2.0; P = 0.003) at week 24 in the SAM cohort compared with non-SAM cohort. Treatment-related grade ≥3 events did not differ significantly between cohorts (24.0% vs. 25.9%).

CONCLUSION

PK and safety findings for ZDV, 3TC, and LPV/r support current WHO weight band dosing of syrup formulations in children with SAM.

Plasma pharmacokinetics and urinary excretion of tenofovir following cessation in adults with controlled levels of adherence to tenofovir disoproxil fumarate

OBJECTIVES

The aim was to fully characterize the plasma and urine washout pharmacokinetics of tenofovir (TFV) in adults following 6 weeks of controlled levels of tenofovir disoproxil fumarate (TDF) adherence, in order to inform the utility of clinic-based adherence testing.

DESIGN

This was a three-arm, randomized, open-label study in adult volunteers. Participants were randomized to receive TDF 300 mg/emtricitabine (FTC) 200 mg as (1) 7 doses/week (perfect adherence), (2) 4 doses/week (moderate adherence), or (3) 2 doses/week (low adherence). Plasma and urine samples were collected regularly during the 6-week dosing phase and for 4 weeks following drug cessation.

RESULTS

Twenty-eight adults were included in this analysis. Median (range) age was 33 (20-49) years. No differences in TFV pharmacokinetic parameters during the washout were observed across the study arms. Small differences in TFV plasma concentrations occurred across arms between 4 and 10 h post-dose. The cumulative amount of TFV excreted in urine was not different at 24 h post-dose, but at 148 h it was 24.8 mg, 21.0 mg, and 17.2 mg for the perfect, moderate, and low adherence arms, respectively (p = 0.043).

CONCLUSIONS

Among adults with different TDF adherence patterns, relative differences in plasma concentrations and cumulative urine extraction of TFV were minor following cessation. TFV measurement in plasma or urine is more indicative of last drug ingestion, rather than prior dose patterns.

Once-weekly rifapentine and isoniazid for tuberculosis prevention in patients with HIV taking dolutegravir-based antiretroviral therapy: a phase 1/2 trial

BACKGROUND

Short-course preventive therapy with 12 doses of once-weekly rifapentine (900 mg) plus isoniazid (900 mg) could greatly improve tuberculosis control, especially in areas with high co-endemicity with HIV. However, a small previous trial of such therapy with dolutegravir in healthy, HIV-negative adults was halted early after two of the four patients developed serious adverse events. Because of the potential use of this therapy, and variable safety outcomes of tuberculosis drugs seen in patients with and without HIV, we aimed to characterise safety, pharmacokinetics, and virological suppression in adults who are HIV positive.

METHODS

DOLPHIN was a phase 1/2, single-arm trial done at The Aurum Institute (Tembisa Clinical Research Site, Tembisa, South Africa), with pharmacokinetic visits done at VxPharma (Pretoria, South Africa). Adults (≥18 years) with HIV infection and undetectable viral load (<40 copies per mL) after at least 8 weeks of efavirenz-based or dolutegravir-based regimens were recruited in three consecutive groups, subject to approval by the independent safety monitoring committee. Participants received 50 mg of daily dolutegravir in place of efavirenz for 8 weeks, then began once-weekly rifapentine (900 mg)-isoniazid (900 mg) for 12 weeks. Groups 1A (n=12) and 1B (n=18) had intensive dolutegravir pharmacokinetic sampling at week 8 (before rifapentine-isoniazid), at week 11 (after the third dose of rifapentine)-isoniazid and at week 16 after the eighth dose. Group 2 (n=30) were treated with the same schedule and had sparse dolutegravir pharmacokinetic sampling at weeks 8, 11, and 16. Participants were followed 4 weeks after completion of prophylactic tuberculosis treatment. HIV viral loads were measured at baseline and at weeks 11 and 24. Primary endpoints were adverse events (grade 3 or higher) and dolutegravir population pharmacokinetics, assessed in participants who began rifapentine-isoniazid. This trial was registered at ClinicalTrials.gov, NCT03435146.

FINDINGS

Between Jan 24, 2018, and Nov 25, 2018, 61 participants were enrolled into three groups; one participant withdrew (from group 1A). 43 (70%) of 60 participants were women and all participants were black African. Median age was 40 years (IQR 35-48), CD4 cell count was 683 cells per μL (447-935), and body-mass index was 28·9 kg/m² (24·0-32·9). Three grade 3 adverse events occurred; two elevated creatinine and one hypertension. Rifapentine-isoniazid increased dolutegravir clearance by 36% (relative standard error 13%) resulting in a 26% decrease in dolutegravir area under the curve. Overall geometric mean ratio of trough concentrations with versus without rifapentine-isoniazid was 0·53 (90% CI 0·49-0·56) though this ratio varied by day after rifapentine-isoniazid dose. All but one trough value was above the 90% maximal inhibitory concentration for dolutegravir and HIV viral loads were less than 40 copies per mL in all patients.

INTERPRETATION

Our results suggest 12 doses of once-weekly rifapentine-isoniazid can be given for tuberculosis prophylaxis to patients with HIV taking dolutegravir-based antiretroviral therapy, without dose adjustments. Further exploration of the pharmacokinetics, safety, and efficacy in children and pharmacodynamics in individuals naive to antiretroviral therapy is needed.

FUNDING

UNITAID.

Determinants of Viral Resuppression or Persistent Virologic Failure After Initial Failure With Second-Line Antiretroviral Treatment Among Asian Children and Adolescents With HIV

Of 56 children with perinatally acquired human immunodeficiency virus (HIV) who had been prescribed second-line protease inhibitor-based antiretroviral therapy and had ≥1 previous episode of viral failure (HIV RNA, ≥1000 copies/mL), 46% had ≥1, 34% had ≥2, and 23% had ≥3 consecutive episodes of viral failure during the 2 years of follow-up. Two of these children experienced a major protease inhibitor mutation.

How to design a study to evaluate therapeutic drug monitoring in infectious diseases?

BACKGROUND

Therapeutic drug monitoring (TDM) is a tool to personalize and optimize dosing by measuring the drug concentration and subsequently adjusting the dose to reach a target concentration or exposure. The evidence to support TDM is however often ranked as expert opinion. Limitations in study design and sample size have hampered definitive conclusions of the potential added value of TDM.

OBJECTIVES

We aim to give expert opinion and discuss the main points and limitations of available data from antibiotic TDM trials and emphasize key elements for consideration in design of future clinical studies to quantify the benefits of TDM.

SOURCES

The sources were peer-reviewed publications, guidelines and expert opinions from the field of TDM.

CONTENT

This review focuses on key aspects of antimicrobial TDM study design: describing the rationale for a TDM study, assessing the exposure of a drug, assessing susceptibility of pathogens and selecting appropriate clinical endpoints. Moreover we provide guidance on appropriate study design.

IMPLICATIONS

This is an overview of different aspects relevant for the conduct of a TDM study. We believe that this paper will help researchers and clinicians to design and conduct high-quality TDM studies.

Sources of Variability and Accuracy of Performance Assessment in the Clinical Pharmacology Quality Assurance Proficiency Testing Program for Antiretrovirals

BACKGROUND

The Clinical Pharmacology Quality Assurance (CPQA) program provides semiannual proficiency testing (PT) of antiretroviral analytes for 11 US and international clinical pharmacology laboratories (CPLs) to ensure interlaboratory comparability. In this article, we provide estimates of the main sources of variability and assess the accuracy of the algorithm for the assessment of performance.

METHODS

Descriptive statistics are reported from 13 PT rounds from 2010 to 2016. Eight of the most common antiretroviral analytes were examined. Variance components analysis was used to rank the relative contributions of CPLs, antiretroviral analyte, and concentration category (low, medium, and high) to bias and variability using mixed models. Binary classification metrics of the PT assessment algorithm are calculated in comparison with a model using 95% prediction limits around estimated regression equations.

RESULTS

CPLs provided 4109 reported concentrations of 65 unique samples for each of the 8 antiretroviral analytes across 13 PT rounds. Individual CPL accounted for the greatest amount of total variability (4.4%). Individual CPL and analyte combination (interaction) accounted for the greatest amount of bias (8.1%). Analyte alone accounted for 0.5% or less for total variability and bias. Overall, using a ±20% acceptance window around the final target, 97% of individual reported concentrations were scored acceptable, and 96% of antiretroviral/round scores were deemed satisfactory. Comparison with the regression model gave 100% sensitivity but only 34.47% specificity. Narrowing the acceptance window to ±15% improved specificity to 84.47% while maintaining a 99.17% sensitivity.

CONCLUSIONS

The current CPQA PT scoring algorithm that use a ±20% acceptance window seems to suffer from a low specificity and may be too lenient. A stricter ±15% acceptance window would increase specificity and overall accuracy while lowering the overall pass rate by only 3%.

Curlin M, Holtz TH, Mannheimer S, Marzinke MA, Amico KR, Liu A, Piwowar-Manning E, Eshleman SH, Dye BJ, Gandhi M, Grant RM. Short- and Long-Term Pharmacologic Measures of HIV Pre-exposure Prophylaxis Use Among High-Risk Men Who Have Sex With Men in HPTN 067/ADAPT

BACKGROUND

The effectiveness of oral emtricitabine (FTC)/tenofovir (TFV) disoproxil fumarate-based HIV pre-exposure prophylaxis (PrEP) depends on adherence. Pharmacologic measures help interpret patterns and predictors of PrEP adherence.

SETTING

We analyzed data from the subsample of men who have sex with men enrolled in HPTN 067/ADAPT in Bangkok, Thailand, and Harlem, NY, U.S.

METHODS

After a 5-week directly observed therapy period, participants were randomized to daily, time-driven, or event-driven PrEP. Follow-up occurred at weeks 4, 12, and 24 after randomization. Plasma and hair FTC/TFV levels indicated short- and long-term PrEP use, respectively. Electronic pill bottle data (Wisepill) were collected weekly. Pearson correlation coefficients between PrEP use measures were calculated; linear mixed models assessed predictors of plasma and hair drug concentrations.

RESULTS

Among 350 participants (median age: 31 years, interquartile range: 25-38), 49.7% were from Harlem, half had less than college education, and 21% reported heavy alcohol use. In multivariable models, being enrolled in Harlem, being in non-daily arms, and having less than college education were associated with lower hair FTC/TFV concentrations; heavy alcohol use was associated with higher concentrations. Similar results were found for plasma concentrations by site and arm, but older age and greater number of sex partners were associated with higher concentrations. Hair and plasma FTC/TFV concentrations were moderately correlated with Wisepill data (r ≥ 0.29) across visits.

CONCLUSIONS

In HPTN067, plasma, hair, and Wisepill data correlated with one another and served as complementary adherence measures. Site, arm, education, age, alcohol, and sexual behavior influenced patterns of adherence.

Development and validation of a high performance liquid chromatography method to determine nevirapine in plasma in a resource-limited setting

Background

There are several instances where nevirapine pharmacokinetic monitoring may be useful, such as in special populations or pharmacokinetic drug interaction studies that require the ascertainment of nevirapine pharmacokinetics in the sub-Saharan region.

Objectives

The main aim of this study was to produce a validated, sustainable and relevant nevirapine assay method that meets bio-analytical regulatory requirements.

Methods

The developed method utilised a Waters 2795 Alliance high performance liquid chromatography system with a 2996 photo diode array detector, an Atlantis dC18 5 micron, 3.9 mm × 150 mm analytical column and a gradient flow rate of 1 mL/min. Ultraviolet detection data were collected from 210 nm to 400 nm, extracted at 260 nm, and processed for nevirapine and internal standard peak height responses.

Results

The method proved to be linear (R2 0.995), precise (+1.92% – +9.69%) and accurate (-9.70% – 12.0%). Recovery for the analyte and internal standard was between 98.8% and 114%. The method showed good specificity as no interferences were caused by common African traditional medicines, anti-tuberculosis medications or other concomitant antiretrovirals nor endogenous components.

Conclusion

The method is reproducible, relevant to our setting and uses considerably low plasma volumes with preservation of some consumables, a desirable key factor in a resource-limited setting.

Boceprevir and Antiretroviral Pharmacokinetic Interactions in HIV/HCV Co-infected Persons: AIDS Clinical Trials Group Study A5309s

OBJECTIVE

The objective of this study was to determine the magnitude of drug interactions between the hepatitis C virus (HCV) protease inhibitor boceprevir (BOC) and antiretroviral (ARV) agents in persons with HIV/HCV co-infection.

METHODS

Participants taking two nucleos(t)ide analogs with either efavirenz, raltegravir, or ritonavir-boosted atazanavir, darunavir, or lopinavir underwent intensive pharmacokinetic (PK) sampling for ARV 2 weeks before (week 2) and 2 weeks after initiating BOC (week 6) and for BOC at week 6. Geometric mean ratios (GMRs) and 90% confidence intervals (CIs) were used to compare ARV PK at weeks 2 and 6 and BOC PK at week 6 to historical data (HD) in healthy volunteers and HCV mono-infected patients.

RESULTS

ARV PK was available for 55 participants. BOC reduced atazanavir and darunavir exposures by 30 and 42%, respectively. BOC increased raltegravir maximum concentration (C _max) by 71%. BOC did not alter efavirenz PK. BOC PK was available for 53 participants. BOC exposures were similar in these HIV/HCV co-infected participants compared with HD in healthy volunteers, but BOC minimum concentrations (C _min) were lower with all ARV agents (by 34-73%) compared with HD in HCV mono-infected patients.

CONCLUSIONS

Effects of BOC on ARV PK in these HIV/HCV co-infected individuals were similar to prior studies in healthy volunteers. However, some differences in the effects of ARV on BOC PK were observed, indicating the magnitude of interactions may differ in HCV-infected individuals versus healthy volunteers. Findings highlight the need to conduct interaction studies with HCV therapies in the population likely to receive the combination.

Brief Report: Lopinavir Hair Concentrations Are the Strongest Predictor of Viremia in HIV-Infected Asian Children and Adolescents on Second-Line Antiretroviral Therapy

BACKGROUND

Children/adolescents display suboptimal antiretroviral therapy (ART) adherence and outcomes versus adults. Hair ART concentrations are objective adherence measures that predict viremia in adults but longitudinal data on hair levels in pediatric populations is limited. We assessed the predictive utility of hair lopinavir (LPV) levels on viremia among youth on second-line ART.

METHODS

We examined predictors of viremia (HIV-1 RNA >400 and >1000 copies/mL) at least 24 weeks after switch to LPV-based second-line ART in a cohort of HIV-infected Asian children followed between 2011 and 2014. Small hair samples, HIV-1 RNA, and self-reported adherence were collected biannually. Hair concentrations of LPV were measured through liquid chromatography/tandem mass spectrometry using validated methods. Time-to-first viremia was examined using discrete-time Cox models.

RESULTS

Overall, 244 children met the inclusion criteria for the present analysis. Approximately half (55%) were boys and the median age 10 years [interquartile range (IQR) 7-13]; 40% were older than 11 years. At switch to second-line ART, median CD4 count was 300 (IQR 146-547) cells/mm and median HIV-RNA level was 5.0 (IQR 4.3-5.6) log10/mL. Median time of study follow-up was 48 weeks and a median of 3 (range 1-5) hair samples were collected from each participant. Adjusting for age, sex, country, self-reported adherence, CD4, and HIV-RNA, higher LPV hair concentrations were the strongest predictor of lower odds of viremia (HIV-RNA >400 copies/mL adjusted odds ratio = 0.41 per doubling in hair concentration, 95% confidence interval: 0.29 to 0.58, P < 0.001; HIV-RNA >1000 copies/mL, adjusted odds ratio = 0.54, 95% confidence interval: 0.45 to 0.65, P < 0.001).

CONCLUSIONS

Hair concentrations predict viremia among children with HIV on second-line ART and could guide clinical decisions for this population.

Strategic establishment of an International Pharmacology Specialty Laboratory in a resource-limited setting

Background

A growing number of drug development studies that include pharmacokinetic evaluations are conducted in regions lacking a specialised pharmacology laboratory. This necessitated the development of an International Pharmacology Specialty Laboratory (IPSL) in Zimbabwe.

Objectives

The aim of this article is to describe the development of an IPSL in Zimbabwe.

Methods

The IPSL was developed collaboratively by the University of Zimbabwe and the University at Buffalo Center for Integrated Global Biomedical Sciences. Key stages included infrastructure development, establishment of quality management systems and collaborative mentorship in clinical pharmacology study design and chromatographic assay development and validation.

Results

Two high performance liquid chromatography instruments were donated by an instrument manufacturer and a contract research organisation. Laboratory space was acquired through association with the Zimbabwe national drug regulatory authority. Operational policies, standard operating procedures and a document control system were established. Scientists and technicians were trained in aspects relevant to IPSL operations. A high-performance liquid chromatography method for nevirapine was developed with the guidance of the Clinical Pharmacology Quality Assurance programme and approved by the assay method review programme. The University of Zimbabwe IPSL is engaged with the United States National Institute of Allergy and Infectious Diseases Division of AIDS research networks and is poised to begin drug assays and pharmacokinetic analyses.

Conclusions

An IPSL has been successfully established in a resource-limited setting through the efforts of an external partnership providing technical guidance and motivated internal faculty and staff. Strategic partnerships were beneficial in navigating challenges leading to laboratory development and training new investigators. The IPSL is now engaged in clinical pharmacology research.

Development and validation of a liquid chromatographic-tandem mass spectrometric method for the multiplexed quantification of etravirine, maraviroc, raltegravir, and rilpivirine in human plasma and tissue

BACKGROUND

Analytical methodologies for antiretroviral (ARV) quantification are important in determining both systemic and localized drug concentrations. The CCR5-antagonist maraviroc (MVC), the non-nucleoside reverse transcriptase inhibitors (NNRTIs) etravirine (ETV) and rilpivirine (RPV), as well as the integrase strand transfer inhibitor (INSTI) raltegravir (RAL), have all been evaluated using both oral and non-oral dosing regimens, demonstrating a need for dynamic and sensitive bioanalytical tools for drug quantification in plasma and tissue.

METHODS

K₂EDTA plasma or blank luminal tissue lysate were spiked with ETV, MVC, RAL, and RPV. Following the addition of isotopically-labeled internal standards and sample extraction via protein precipitation or solid phase extraction, respectively, samples were subjected to liquid chromatographic-tandem mass spectrometric (LC-MS/MS) analysis. Chromatographic separation was performed using a Waters BEH C8, 50×2.1mm, 1.7μm particle size column, and detected on an API 5000 mass analyzer operated in selective reaction monitoring mode. The method was validated according to FDA Bioanalytical Method Validation guidelines.

RESULTS

Analytical methods were optimized for the multiplexed monitoring of ETV, MVC, RAL, and RPV in plasma and homogenized tissue lysate. The lower limits of quantification (LLOQs) for ETV, RAL, and RPV were 1ng/mL and the LLOQ for MVC was 0.1ng/mL in plasma; the LLOQs for all ARVs in homogenized tissue lysate was 0.05ng/sample. Standard curves were generated via weighted quadratic (plasma) or linear (tissue) regression of calibrators. Intra- and inter-assay precision and accuracy studies demonstrated %CVs≤15.93% and %DEVs ≤±13.52%, respectively. Stability and matrix effects studies, as well as external proficiency testing assessment, were also performed. All results were acceptable and in accordance with the guidelines recommended by the FDA, Guidance for Industry: Bioanalytical Method Validation document.

CONCLUSIONS

LC-MS/MS assays that are sensitive, specific, and dynamic have been developed and validated for the multiplexed quantification of ETV, MVC, RAL, and RPV in plasma and homogenized tissue lysate. The described methods meet sufficient throughput criteria to support large research trials.

Pharmacokinetics of Once Versus Twice Daily Darunavir in Pregnant HIV-Infected Women

OBJECTIVE

To describe darunavir (DRV) pharmacokinetics with once-and twice-daily dosing during pregnancy and postpartum in HIV-infected women.

DESIGN

Women were enrolled in International Maternal Pediatric Adolescent AIDS Clinical Trials Network Protocol P1026s, a prospective nonblinded study of antiretroviral pharmacokinetics in HIV-infected pregnant women that included separate cohorts receiving DRV/ritonavir dosed at either 800 mg/100 mg once daily or 600 mg/100 mg twice daily.

METHODS

Intensive steady-state 12- or 24-hour pharmacokinetic profiles were performed during the second trimester, third trimester, and postpartum. DRV was measured using high-performance liquid chromatography (detection limit: 0.09 μg/mL).

RESULTS

Pharmacokinetic data were available for 64 women (30 once daily and 34 twice daily dosing). Median DRV area under the concentration-time curve (AUC) and maximum concentration were significantly reduced during pregnancy with both dosing regimens compared with postpartum, whereas the last measurable concentration (Clast) was also reduced during pregnancy with once daily DRV. DRV AUC with once daily dosing was reduced by 38% during the second trimester and by 39% during the third trimester. With twice daily dosing, DRV AUC was reduced by 26% in both trimesters. The median (range) ratio of cord blood/maternal delivery DRV concentration in 32 paired samples was 0.18 (range: 0-0.82).

CONCLUSIONS

DRV exposure is reduced by pregnancy. To achieve DRV plasma concentrations during pregnancy equivalent to those seen in nonpregnant adults, an increased twice daily dose may be necessary. This may be especially important for treatment-experienced women who may have developed antiretroviral resistance mutations.

Expedient screening for HIV-1 protease inhibitors using a simplified immunochromatographic assay

A colloidal gold-based immunochromatographic (IC) strip test was developed and validated for the detection of HIV-1 protease (HIV-PR) activity and inhibitory effect of HIV-PR inhibitors (PIs). It is a unique 'two-step' process requiring the combination of proteolysis of HIV-PR and an immunochromatographic reaction. Monoclonal antibodies to the free C-terminus of HIV matrix protein (HIV-MA) conjugated to gold particles and a monoclonal antibody against intact and cleaved forms of the HIV-MA are immobilized on the 'Test'-line of the IC strip. Using lopinavir, a potent HIV protease inhibitor, the IC-strip was optimized to detect inhibitory activity against HIV-protease. At a lopinavir concentration of 1000ng/mL (its suggested minimum effective concentration), a HIV-PRH6 concentration of 6mg/mL and incubation period of 60min were the optimal conditions. A preliminary comparison between a validated high-performance liquid chromatography assay and the IC-strip to semi-quantify HIV protease inhibitor concentrations (lopinavir and atazanavir) demonstrated good agreement. This simplified method is suitable for the rapid screening of novel protease inhibitors for future therapeutic use. Moreover, the IC strip could also be optimized to semi-quantify PIs concentrations in plasma samples.

Adding value to antiretroviral proficiency testing

BACKGROUND

Clinical trial specimens tested for antiretroviral (ARV) concentrations often require compliance with Clinical Laboratory Improvement Act and/or the Food and Drug Administration bioanalytical guidance.

EXPERIMENTAL

The Clinical Pharmacology Quality Assurance Program (CPQA) designed 8 proficiency testing (PT) rounds over 4 years to assess precision, specificity and stability.

RESULTS

Ten laboratories provided blinded proficiency data to support continued acceptable precision of ARV methods. Specificity samples identified little bias for individual methods; hemolyzed (87%) and lipemic (86%) results were ≤ 10% of their control results. Stability was established for ARVs in plasma at -70°C for 2.5-3.6 years.

CONCLUSION

PT provided by the CPQA assured continued acceptability of individual laboratory assay performances for precision and specificity, and obtained ARV stability during long term storage.

PHARMACOKINETIC EXPOSURE AND VIROLOGIC RESPONSE IN HIV-1 INFECTED PREGNANT WOMEN TREATED WITH LOPINAVIR/RITONAVIR: AIDS CLINICAL TRIALS GROUP PROTOCOL A5153S: A SUBSTUDY TO A5150

OBJECTIVE

We studied the pharmacokinetics and pharmacodynamics of boosted soft-gel lopinavir/ritonavir to assess if the area under the plasma concentration versus time curve (AUC) is altered in pregnancy and whether changes in AUC impacted HIV-1 control.

METHODS

We enrolled pregnant women ≥13 years of age between 22 to 30 weeks gestation who expected to be on stable lopinavir/ritonavir for ≥8 weeks pre-delivery and ≥24 weeks post-delivery. Pharmacokinetic evaluations for lopinavir and ritonavir occurred at 36 weeks gestation and 6 and 24 weeks postpartum.

RESULTS

Ten women underwent intensive pharmacokinetic evaluations for lopinavir and ritonavir at 36 weeks gestation and at 6 and 24 weeks postpartum. Estimated geometric mean (GM) AUC 0-6h (95% CI) for lopinavir were not significantly different at 26.5 (17.0, 41.4) and 41.9 (26.1, 67.5) mcg*hr/mL at 36 weeks gestation and 6 weeks postpartum, respectively (within-subject GM ratio 0.60 (0.25, 1.43); p=0.19). At 36 weeks gestation, 5 of 10 women had viral load <50 copies/mL and at 6 weeks postpartum 5 of 9 had viral load <50 copies/mL. Nine of ten infants for whom data were available were HIV negative.

CONCLUSION

Despite below target lopinavir levels (< 52 mcg*hr/mL except at 2 postpartum measurements), women maintained virologic control postpartum. Higher doses of lopinavir/ritonavir during pregnancy may not be necessary in all women.

Impact of body weight and missed doses on lopinavir concentrations with standard and increased lopinavir/ritonavir doses during late pregnancy

OBJECTIVES

To assess the influence of body weight and missed doses on lopinavir pharmacokinetics with standard and increased doses of lopinavir/ritonavir melt extrusion tablets during late pregnancy.

PATIENTS AND METHODS

Lopinavir concentration data during the third trimester of pregnancy were pooled from clinical trials in Thailand (NCT00409591) and the USA (NCT00042289). A total of 154 HIV-infected pregnant women receiving either 400/100 mg (standard) or 600/150 mg (increased) twice daily had lopinavir plasma concentration data available. Population parameters were estimated using non-linear mixed-effects regression models. Monte Carlo simulations were performed to estimate the probability of achieving target lopinavir trough concentrations (>1.0 mg/L) with standard and increased doses of lopinavir/ritonavir during pregnancy.

RESULTS

The median (range) age, weight and gestational age were 28 years (18-43), 62 kg (45-123) and 33 weeks (29-38), respectively. Body weight influenced lopinavir oral clearance (CL/F) and volume of distribution (V/F). Population estimates of lopinavir CL/F and V/F were 6.21 L/h/70 kg and 52.6 L/70 kg, respectively. Based on simulations, the highest risk of subtherapeutic trough concentrations was for women weighing >100 kg using the standard dose (∼ 7%), while the risk was <2% with the 600/150 mg dose for women weighing 40-130 kg. After a missed dose, 61% of women have lopinavir concentrations below target prior to the next dose with the standard dose compared with 42% with the increased dose.

CONCLUSIONS

Standard dosing provides adequate lopinavir trough concentrations for the majority of pregnant women but increased doses may be preferable for women weighing >100 kg and with a history of lopinavir/ritonavir use and/or adherence issues.

Introduction to a Special Issue of the Journal of Immunological Methods: Building global resource programs to support HIV/AIDS clinical trial studies

This Special Issue of the Journal of Immunological Methods includes 16 manuscripts describing quality assurance activities related to virologic and immunologic monitoring of six global laboratory resource programs that support international HIV/AIDS clinical trial studies: Collaboration for AIDS Vaccine Discovery (CAVD); Center for HIV/AIDS Vaccine Immunology (CHAVI); External Quality Assurance Program Oversight Laboratory (EQAPOL); HIV Vaccine Trial Network (HVTN); International AIDS Vaccine Initiative (IAVI); and Immunology Quality Assessment (IQA). The reports from these programs address the many components required to develop comprehensive quality control activities and subsequent quality assurance programs for immune monitoring in global clinical trials including: all aspects of processing, storing, and quality assessment of PBMC preparations used ubiquitously in HIV clinical trials, the development and optimization of assays for CD8 HIV responses and HIV neutralization, a comprehensive global HIV virus repository, and reports on the development and execution of novel external proficiency testing programs for immunophenotyping, intracellular cytokine staining, ELISPOT and luminex based cytokine measurements. In addition, there are articles describing the implementation of Good Clinical Laboratory Practices (GCLP) in a large quality assurance laboratory, the development of statistical methods specific for external proficiency testing assessment, a discussion on the ability to set objective thresholds for measuring rare events by flow cytometry, and finally, a manuscript which addresses a framework for the structured reporting of T cell immune function based assays. It is anticipated that this series of manuscripts covering a wide range of quality assurance activities associated with the conduct of global clinical trials will provide a resource for individuals and programs involved in improving the harmonization, standardization, accuracy, and sensitivity of virologic and immunologic testing.