Fragment Addition-Based Design of Heteroaromatic-Biphenyl-DAPYs as Potent and Orally Available Non-nucleoside Reverse Transcriptase Inhibitors Featuring Significantly Enhanced Safety.

Our previously disclosed biphenyl-DAPY 3 emerged as a potent inhibitor against WT HIV-1 and various mutant strains. Yet, its journey toward clinical application was thwarted by pronounced cytotoxicity and low selectivity (CC50 = 6 µM, SI = 3515). The safety improvement approach we employed in this work entailed the incorporation of diverse heteroaromatic substituents at the C5 position to exploit the tolerant regions of the NNRTIs' binding pocket through fragment addition-based drug design strategy, ultimately leading to the identification of a series of novel heteroaromatic-biphenyl-DAPYs. The exemplary compound 10d revealed a striking reduction in cytotoxicity (CC50 > 272.81 µM), nearly 45.5 times lower than 3, while showcasing 15-fold increase in selectivity (SI > 52632). This analog sustained exceptional anti-HIV-1 activity against both WT HIV-1 (EC50 = 5 nM) and various mutant strains. Compared to 3, a markedly slower rate of metabolism in human liver microsomes of 10d was observed. Its pharmacokinetic profile was equally captivating, featuring excellent oral bioavailability (F = 57.4%). Moreover, 10d exhibited a delicate sensitivity toward CYP, minimal inhibition of hERG, and no detectable acute toxicity in vivo. These enchanting findings illuminated the potential of 10d as a promising candidate for HIV-1 therapy.

Influence of age and co-medication on dolutegravir glucuronidation in paediatric patients.

Dolutegravir (DTG) is primarily metabolized by uridine diphosphate glucuronosyltransferases, forming the pharmacologically inactive DTG glucuronide (DTG-gluc). We described the dolutegravir metabolic ratio (DTG-MR; DTG-gluc AUC0-24h divided by DTG AUC0-24h) in 85 children with HIV aged 3 months to 18 years receiving DTG in the CHAPAS-4 (ISRCTN22964075) and ODYSSEY (NCT02259127) trials. Additionally, we assessed the influence of age, body weight, nucleoside/nucleotide reverse transcriptase inhibitor (NRTI) backbone, rifampicin use and kidney function on DTG-MR. The overall geometric mean (CV%) DTG-MR was 0.054 (52%). Rifampicin use was the only significant factor associated with DTG-MR (P < .001) in multiple linear regression. DTG-MR geometric mean ratio was 1.81 (95% CI: 1.57-2.08) for children while on vs. off rifampicin. This study showed that overall DTG-MR in children was similar to adults, unaffected by age or NRTI backbone, and increased with rifampicin co-administration. These findings support future paediatric pharmacokinetic modelling and extrapolation from adult data.

Intracellular islatravir-triphosphate half-life supports extended dosing intervals.

Antiretroviral therapy has substantially reduced morbidity, mortality, and disease transmission in people living with HIV. Islatravir is a nucleoside reverse transcriptase translocation inhibitor that inhibits HIV-1 replication by multiple mechanisms of action, and it is in development for the treatment of HIV-1 infection. In preclinical and clinical studies, islatravir had a long half-life (t½) of 3.0 and 8.7 days (72 and 209 hours, respectively); therefore, islatravir is being investigated as a long-acting oral antiretroviral agent. A study was conducted to definitively elucidate the terminal t½ of islatravir and its active form islatravir-triphosphate (islatravir-TP). A single-site, open-label, non-randomized, single-dose phase 1 study was performed to evaluate the pharmacokinetics and safety of islatravir in plasma and the pharmacokinetics of islatravir-TP in peripheral blood mononuclear cells after administration of a single oral dose of islatravir 30 mg. Eligible participants were healthy adult males without HIV infection between the ages of 18 and 65 years. Fourteen participants were enrolled. The median time to maximum plasma islatravir concentration was 1 hour. Plasma islatravir concentrations decreased in a biphasic manner, with a t½ of 73 hours. The t½ (percentage geometric coefficient of variation) of islatravir-TP in peripheral blood mononuclear cells through 6 weeks (~1008 hours) after dosing was 8.1 days or 195 hours (25.6%). Islatravir was generally well tolerated with no drug-related adverse events observed. Islatravir-TP has a long intracellular t½, supporting further clinical investigation of islatravir administered at an extended dosing interval.

Population pharmacokinetics of Ainuovirine and exposure-response analysis in human immunodeficiency virus-infected individuals.

BACKGROUND: Ainuovirine (ANV) is a new generation of non-nucleoside reverse transcriptase inhibitor for the treatment of human immunodeficiency virus (HIV) type 1 infection. This study aimed to evaluate the population pharmacokinetic (PopPK) profile and exposure-response relationship of ANV among people living with HIV. METHODS: Plasma concentration-time data from phase 1 and phase 3 clinical trials of ANV were pooled for developing the PopPK model. Exposure estimates obtained from the final model were used in exposure-response analysis for virologic responses and safety responses. RESULTS: ANV exhibited a nonlinear pharmacokinetic profile, which was best described by a two-compartment model with first-order elimination. There were no significant covariates correlated to the pharmacokinetic parameters of ANV. The PopPK parameter estimate (relative standard error [%]) for clearance adjusted for bioavailability (CL/F) was 6.46 (15.00) L/h, and the clearance of ANV increased after multiple doses. The exposure-response model revealed no significant correlation between the virologic response (HIV-RNA <50 copies/mL) at 48 weeks and the exposure, but the incidence of adverse events increased with the increasing exposure ( P value of steady-state trough concentration and area under the steady-state curve were 0.0177 and 0.0141, respectively). CONCLUSIONS: Our PopPK model supported ANV 150 mg once daily as the recommended dose for people living with HIV, requiring no dose adjustment for the studied factors. Optimization of ANV dose may be warranted in clinical practice due to an increasing trend in adverse reactions with increasing exposure. TRIAL REGISTRATION: Chinese Clinical Trial Registry https://www.chictr.org.cn (Nos. ChiCTR1800018022 and ChiCTR1800019041).

Pharmacogenetics of Efavirenz Exposure in Cervicovaginal Fluid during Pregnancy and Postpartum.

In this study, we investigated the combined influence of pregnancy and genetic polymorphisms on efavirenz pharmacokinetics in cervicovaginal fluid (CVF) of women receiving antiretroviral therapy. Women receiving efavirenz-containing antiretroviral therapy were recruited from two hospitals in Nigeria during 2017-2020. Sparse CVF and plasma samples were obtained during pregnancy to assess the possible association between drug concentration and CYP2B6 polymorphisms (stage I). Participants were stratified into three CYP2B6 516G>T (rs3745274) genotype groups and re-enrolled for intensive pharmacokinetic sampling (stage II). Overall, 159 women (142 pregnant and 12 postpartum) contributed samples in stage I (88 CVF, 81 plasma and 73 paired). CYP2B6 516G>T (rs3745274) remained independently associated with log10 efavirenz CVF concentration during pregnancy after adjusting for plasma concentration, with ß (Log10 efavirenz concentration, 95%CI) of 0.204 (0.027, 0.382), P = 0.025). Median (IQR) efavirenz C min in CVF during pregnancy (n = 12) vs. postpartum (n = 12) was 243 ng/mL (168-402) vs. 447 ng/mL (159-974), C max was 1,031 ng/mL (595-1,771) vs. 1,618 ng/mL (675-2,695), and AUC0-24h was 16,465 ng.h/mL (9,356-30,417) vs. 30,715 ng.h/mL (10,980-43,714). CVF-to-plasma AUC ratio was 0.36 during pregnancy and 0.46 postpartum. Upon stratification, efavirenz clearance during pregnancy was 57.9% higher than postpartum in patients with the CYP2B6 516GT genotype; the AUC0-24h and C max were 33.8% and 8.6% lower, respectively. Efavirenz C min in CVF exceeded the protein binding-adjusted IC90 (PBIC90) of 126 ng/mL during pregnancy and postpartum. Efavirenz is well distributed into the CVF; both pregnancy and CYP2B6 polymorphisms affect the extent of exposure.

Exploring the Impact of Efavirenz on Aflatoxin B1 Metabolism: Insights from a Physiologically Based Pharmacokinetic Model and a Human Liver Microsome Study.

Physiologically based pharmacokinetic (PBPK) models were utilized to investigate potential interactions between aflatoxin B1 (AFB1) and efavirenz (EFV), a non-nucleoside reverse transcriptase inhibitor drug and inducer of several CYP enzymes, including CYP3A4. PBPK simulations were conducted in a North European Caucasian and Black South African population, considering different dosing scenarios. The simulations predicted the impact of EFV on AFB1 metabolism via CYP3A4 and CYP1A2. In vitro experiments using human liver microsomes (HLM) were performed to verify the PBPK predictions for both single- and multiple-dose exposures to EFV. Results showed no significant difference in the formation of AFB1 metabolites when combined with EFV (0.15 µM) compared to AFB1 alone. However, exposure to 5 µM of EFV, mimicking chronic exposure, resulted in increased CYP3A4 activity, affecting metabolite formation. While co-incubation with EFV reduced the formation of certain AFB1 metabolites, other outcomes varied and could not be fully attributed to CYP3A4 induction. Overall, this study provides evidence that EFV, and potentially other CYP1A2/CYP3A4 perpetrators, can impact AFB1 metabolism, leading to altered exposure to toxic metabolites. The results emphasize the importance of considering drug interactions when assessing the risks associated with mycotoxin exposure in individuals undergoing HIV therapy in a European and African context.

Prenatal efavirenz exposure is independently associated with maternal, but not fetal CYP2B6 genotype.

OBJECTIVES: Understanding the influence of fetal and maternal genetics on prenatal drug exposure could potentially improve benefit-risk evaluation. In this study, we investigated the impact of two functional polymorphisms in CYP2B6 on prenatal exposure to efavirenz. METHODS: Dried blood spot (DBS) samples were collected from HIV-positive pregnant women ( n  = 112) and their newborns ( n  = 107) at delivery. They were genotyped for single nucleotide polymorphisms in CYP2B6. Efavirenz was quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). RESULTS: Significant correlations were observed in efavirenz concentration between maternal and newborn ( r  = 0.46, R2  = 0.21, P  < 0.001), and maternal and cord ( r  = 0.83, R2  = 0.68, P  < 0.001) samples. Median (interquartile range) newborn plasma-to-maternal plasma and cord-to-maternal plasma ratios were 0.85 (0.03-3.49) and 0.78 (0.23-1.96), respectively. Newborn efavirenz concentration in DBS varied significantly based on composite maternal CYP2B6 genotype: fast ( CYP2B6 516GG and 983TT, n  = 26), 747 ng/ml (602-1060); intermediate ( CYP2B6 516GT or 983TC n  = 50), 1177 ng/ml (898-1765); and slow ( CYP2B6 516GT and 983TC or 516TT or 983CC, n  = 14), 3094 ng/ml (2126-3812). Composite newborn CYP2B6 genotype was, however, not significantly associated with prenatal exposure. Efavirenz concentration in newborn stratified as fast ( n  = 25), intermediate ( n  = 36), and slow metabolizers ( n  = 19) from prenatal exposure was 999.7 (774-1285), 1240 (709-1984), and 1792 ng/ml (1201-3188), respectively. CONCLUSION: The clinical relevance of the observed influence of maternal genetics on prenatal efavirenz exposure requires further investigation.

D3/Penta 21 clinical trial design: A randomised non-inferiority trial with nested drug licensing substudy to assess dolutegravir and lamivudine fixed dose formulations for the maintenance of virological suppression in children with HIV-1 infection, aged 2 to 15 years.

BACKGROUND: There is increasing interest in utilising two-drug regimens for HIV treatment with the goal of reducing toxicity and improve acceptability. The D3 trial evaluates the efficacy and safety of DTG/3TC in children and adolescents and includes a nested pharmacokinetics(PK) substudy for paediatric drug licensing. METHODS: D3 is an ongoing open-label, phase III, 96-week non-inferiority randomised controlled trial(RCT) conducted in South Africa, Spain, Thailand, Uganda and the United Kingdom. D3 has enrolled 386 children aged 2- < 15 years, virologically suppressed for ≥6 months, with no prior treatment failure. Participants were randomised 1:1 to receive DTG/3TC or DTG plus two nucleoside reverse transcriptase inhibitors(NRTIs), stratified by region, age (2- < 6, 6- < 12, 12- < 15 years) and DTG use at enrolment (participants permitted to start DTG at enrolment). The primary outcome is confirmed HIV-1 RNA viral rebound ≥50 copies/mL by 96-weeks. The trial employs the Smooth Away From Expected(SAFE) non-inferiority frontier, which specifies the non-inferiority margin and significance level based on the observed event risk in the control arm. The nested PK substudy evaluates WHO weight-band-aligned dosing in the DTG/3TC arm. DISCUSSION: D3 is the first comparative trial evaluating DTG/3TC in children and adolescents. Implications of integrating a PK substudy and supplying data for prompt regulatory submission, were carefully considered to ensure the integrity of the ongoing trial. The trial uses an innovative non-inferiority frontier for the primary analysis to allow for a lower-than-expected confirmed viral rebound risk in the control arm, while ensuring interpretability of results and maintaining the planned sample size in an already funded trial. TRIAL REGISTRATION: International Standard Randomised Clinical Trial Number Register: ISRCTN17157458. European Clinical Trials Database: 2020-001426-57. CLINICALTRIALS: gov: NCT04337450.

Discovery of Novel Aryl Triazolone Dihydropyridines (ATDPs) Targeting Highly Conserved Residue W229 as Promising HIV-1 NNRTIs.

NNRTI is an important component of the highly active antiretroviral therapy (HAART), but the rapid emergence of drug resistance and poor pharmacokinetics limited their clinical application. Herein, a series of novel aryl triazolone dihydropyridines (ATDPs) were designed by structure-guided design with the aim of improving drug resistance profiles and pharmacokinetic profiles. Compound 10n (EC50 = 0.009-17.7 µM) exhibited the most active potency, being superior to or comparable to that of doravirine (DOR) against the whole tested viral panel. Molecular docking was performed to clarify the reason for its higher resistance profiles. Moreover, 10n demonstrated excellent pharmacokinetic profile (T1/2 = 5.09 h, F = 108.96%) compared that of DOR (T1/2 = 4.4 h, F = 57%). Additionally, 10n was also verified to have no in vivo acute or subacute toxicity (LD50 > 2000 mg/kg), suggesting that 10n is worth further investigation as a novel oral NNRTIs for HIV-1 therapy.

Population pharmacokinetic analysis of doravirine in real-world people with HIV.

AIMS: The pharmacokinetics of doravirine has been studied in clinical trials but not in real-world settings. Our study aims to characterize and identify factors influencing doravirine (a CYP3A4 substrate) pharmacokinetics in real-world people with HIV (PWH). METHODS: A total of 174 doravirine concentrations measured in 146 PWH followed up in the therapeutic drug monitoring (TDM) program at the University Hospital of Lausanne (Switzerland) between 2019 and 2023 were included in the analysis. Demographic data, clinical information and comedications were recorded during the routine SHCS visits (every 3-6 months). Population pharmacokinetic analysis and Monte Carlo simulations to investigate the clinical significance of the covariates retained in the final model were performed using NONMEM. RESULTS: A one-compartment model with first-order absorption and linear elimination best described doravirine pharmacokinetics. Potent CYP3A4 inhibitors and, to a lesser extent age, were the only tested covariates to significantly impact doravirine clearance (CL). Potent CYP3A4 inhibitors reduced CL by 50%, and a 30% decrease in CL was observed in an 80-year-old compared with a 55-year-old PWH. The effect of potent CYP3A4 inhibitors was prominent, explaining 59% of between-subject variability in CL. Model-based simulations predicted 2.8-fold and 1.6-fold increases in median steady-state trough and maximum doravirine concentrations, respectively, when a potent CYP3A4 inhibitor was co-administered. CONCLUSIONS: Our findings show that potent CYP3A4 inhibitors and age influence doravirine pharmacokinetics. However, given the good tolerability of doravirine, dosing adjustment of doravirine is probably not mandatory in those situations. TDM remains useful essentially in specific clinical situations, such as hepatic impairment, suspected nonadherence or pregnancy.

Synthesis and anti-HIV activity of non-nucleoside reverse-transcriptase inhibitor DB02 phosphate derivatives based on water-soluble optimization.

To improve the water solubility of anti-human immunodeficiency virus (HIV) agent DB02, an excellent non-nucleoside reverse-transcriptase inhibitor (NNRTI) obtained in our previous efforts, we designed and synthesized four phosphate derivatives of DB02 based on the molecular model of DB02 with RT. Here, the antiviral activity of these four derivatives was detected, leading to the discovery of compound P-2, which possessed a superior potency to the lead compound DB02 against wild-type HIV-1 and a variety of HIV-resistant mutant viruses significantly. Furthermore, the water solubility of P-2 was nearly 17 times higher than that of DB02, and the pharmacokinetic test in rats showed that P-2 demonstrate significantly improved oral bioavailablity of 14.6%. Our study showed that the introduction of a phosphate ester group at the end of the C-2 side chain of DB02 was beneficial to the improvement of its antiviral activity and pharmacokinetic properties, which provided a promising lead for the further development of S-DACOs type of NNRTIs.

Development of Novel Dihydrofuro[3,4-d]pyrimidine Derivatives as HIV-1 NNRTIs to Overcome the Highly Resistant Mutant Strains F227L/V106A and K103N/Y181C.

Here, we report the design, synthesis, structure-activity relationship studies, antiviral activity, enzyme inhibition, and druggability evaluation of dihydrofuro[3,4-d]pyrimidine derivatives as a potent class of HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs). Compounds 14b (EC50 = 5.79-28.3 nM) and 16c (EC50 = 2.85-18.0 nM) exhibited superior potency against a panel of HIV-1-resistant strains. Especially, for the changeling mutations F227L/V106A and K103N/Y181C, both compounds exhibited remarkably improved activity compared to those of etravirine and rilpivirine. Moreover, 14b and 16c showed moderate RT enzyme inhibition (IC50 = 0.14-0.15 µM), which demonstrated that they acted as HIV-1 NNRTIs. Furthermore, 14b and 16c exhibited favorable pharmacokinetic and safety properties, making them excellent leads for further development.

Fluoride Pharmacokinetics in Urine and Plasma Following Multiple Doses of MK-8507, an Investigational, Oral, Once-Weekly Nonnucleoside Reverse Transcriptase Inhibitor.

MK-8507 is an investigational HIV-1 nonnucleoside reverse transcriptase inhibitor being developed for the treatment of HIV-1 infection. MK-8507 contains 2 trifluoromethyl groups that may result in fluoride release through metabolism, but the extent of MK-8507-related fluoride release in humans has yet to be determined. This double-blind, placebo-controlled, 2-period, parallel-group, multiple-dose trial in healthy participants without HIV-1 who were administered a fluoride-restricted diet and once-weekly doses of MK-8507 aimed to estimate the relationship between MK-8507 dose and fluoride exposure. A total of 15 adult male and 3 adult female (of non-childbearing potential) participants were randomized to receive MK-8507 200 mg (n = 6), MK-8507 800 mg (n = 6), or placebo (n = 6). Change from baseline in mean daily fluoride excretion averaged over 7 days following the administration of MK-8507 200 mg resulted in a net mean increase of 19.8 µmol (90% confidence interval, 12.2-27.4) relative to placebo and did not exceed 57 µmol, a threshold related to the mean difference between the daily reference dose set by the US Environmental Protection Agency and the average dietary fluoride intake in the United States. However, daily urinary fluoride excretion exceeded the threshold following administration of 800 mg MK-8507 (75.1 µmol [90% confidence interval, 67.5-82.7]). Assuming a linear relationship between MK-8507 dose and estimated mean daily fluoride released at steady-state, data interpolation suggests that the US Environmental Protection Agency reference dose for fluoride would not be exceeded in most patients when administering MK-8507 at doses currently under clinical investigation (≤400 mg once weekly).

Safety and pharmacokinetics of islatravir subdermal implant for HIV-1 pre-exposure prophylaxis: a randomized, placebo-controlled phase 1 trial.

Islatravir (MK-8591) is a highly potent type 1 human immunodeficiency virus (HIV-1) nucleoside reverse transcriptase translocation inhibitor with a long intracellular half-life that is in development for the prevention and treatment of HIV-1. We conducted a randomized, double-blind, placebo-controlled, phase 1 trial in adults without HIV-1 infection. Participants received islatravir or placebo subdermal implants for 12 weeks and were monitored throughout this period and after implant removal. The co-primary end points were safety and tolerability of the islatravir implant and pharmacokinetics, including concentration at day 85, of islatravir triphosphate in peripheral blood mononuclear cells (PBMCs). Secondary end points included additional pharmacokinetic parameters for islatravir triphosphate in PBMCs and the plasma pharmacokinetic profile of islatravir. Based on preclinical data, two doses were assessed: 54 mg (n = 8, two placebo) and 62 mg (n = 8, two placebo). The most frequently reported adverse events were mild-to-moderate implant-site reactions (induration, hematoma, pain). Throughout the 12-week trial, geometric mean islatravir triphosphate concentrations were above a pharmacokinetic threshold of 0.05 pmol per 106 PBMCs, which was estimated to provide therapeutic reverse transcriptase inhibition (concentration at day 85 (percentage of geometric coefficient of variation): 54 mg, 0.135 pmol per 106 cells (27.3); 62 mg, 0.272 pmol per 106 cells (45.2)). Islatravir implants at both doses were safe and resulted in mean concentrations above the pharmacokinetic threshold through 12 weeks, warranting further investigation of islatravir implants as a potential HIV prevention strategy.

Pharmacodynamics of efavirenz 400 mg in treatment-naïve Chinese HIV-infected patients in a prospective cohort study.

BACKGROUND: The plasma concentration of patients treated with efavirenz (EFV) 600 mg was found to exceed the upper limit of the proposed therapeutic window in most Chinese HIV-infected individuals; thus, dosage reduction of EFV to 400 mg daily warranted consideration. This study aimed to assess the pharmacodynamics of EFV 400 mg for HIV-1-infected patients in China. METHOD: Twenty cART-naïve individuals were enrolled in this study. EFV 400 mg combined with tenofovir (TDF) and lamivudine (3TC) as an initial antiretroviral regimen was administered for 48 weeks. EFV concentration and T cell subsets as well as HIV RNA load were evaluated at baseline and at 4, 12, 24, and 48 weeks. Moreover, neuropsychiatric adverse effects were also assessed by the Hamilton depression (HAMD) scale and Pittsburgh sleep quality index (PSQI). RESULTS: Eighteen males and two females whose median age was 26 (interquartile range [IQR]: 23-32) years completed 48 weeks of follow-up. The median EFV concentrations were 1.88 (IQR: 1.54-2.42), 1.74 (IQR: 1.36-1.93), 1.93 (IQR: 1.66-2.22), and 1.85 (IQR: 1.54-2.14) mg/L at weeks 4, 12, 24, and 48, respectively. The viral load was 4.59 (IQR: 4.10-5.19) log10 copies/mL at baseline, and it decreased by 4.6 (IQR: 3.98-5.18) log10 copies/mL from baseline to week 48. Three of 20 (15%), 10 of 20 (50.0%), 17 of 20 (85%), and 18 of 19 (95%) participants had a plasma viral load less than 50 copies/mL at weeks 4, 12, 24, and 48, respectively. The median CD4 cell count was 330 (IQR: 237-410) cells/µL at baseline, and it increased to 473 (IQR: 344-574) cells/µL at 48 weeks. The HAMD score was 5 (IQR: 3-9.8) and 3 (IQR: 2.25-4) at baseline and 48 weeks, respectively. The PSQI score was 4 (IQR: 2-5.8) and 3 (IQR: 2-4) at baseline and 48 weeks, respectively. Dizziness was the most common event, occurring in 70% of patients within the first 2 weeks of treatment. CONCLUSION: Patients prescribed with EFV 400 mg-containing agents demonstrated favourable virological and immunological responses. And the plasma EFV concentration was within the recommended therapeutic range, with fewer adverse reactions than with EFV 600 mg. EFV 400 mg was effective and safe in Chinese HIV-infected patients. TRIAL REGISTRATION: NCT04596488 ; Registered 21 October, 2020; Retrospectively registered.

Physiologically Based Pharmacokinetic Modeling of Doravirine and Its Major Metabolite to Support Dose Adjustment With Rifabutin.

Doravirine, a novel nonnucleoside reverse transcriptase inhibitor for the treatment of human immunodeficiency virus 1 (HIV-1), is predominantly cleared by cytochrome P450 (CYP) 3A4 and metabolized to an oxidative metabolite (M9). Coadministration with rifabutin, a moderate CYP3A4 inducer, decreased doravirine exposure. Based on nonparametric superposition modeling, a doravirine dose adjustment from 100 mg once daily to 100 mg twice daily during rifabutin coadministration was proposed. However, M9 exposure may also be impacted by induction, in addition to the dose adjustment. As M9 concentrations have not been quantified in previous clinical studies, a physiologically based pharmacokinetic model was developed to investigate the change in M9 exposure when doravirine is coadministered with CYP3A inducers. Simulations demonstrated that although CYP3A induction increases doravirine clearance by up to 4.4-fold, M9 exposure is increased by only 1.2-fold relative to exposures for doravirine 100 mg once daily in the absence of CYP3A induction. Thus, a 2.4-fold increase in M9 exposure relative to the clinical dose of doravirine is anticipated when doravirine 100 mg twice daily is coadministered with rifabutin. In a subsequent clinical trial, doravirine and M9 exposures, when doravirine 100 mg twice daily was coadministered with rifabutin, were found to be consistent with model predictions using rifampin and efavirenz as representative inducers. These findings support the dose adjustment to doravirine 100 mg twice daily when coadministered with rifabutin.

Pharmacokinetics and Drug-Drug Interactions of Isoniazid and Efavirenz in Pregnant Women Living With HIV in High TB Incidence Settings: Importance of Genotyping.

The World Health Organization guidelines recommend that individuals living with HIV receive ≥ 6 months of isoniazid preventive therapy, including pregnant women. Yet, plasma isoniazid exposure during pregnancy, in the antiretroviral therapy era, has not been well-described. We investigated pregnancy-induced and pharmacogenetic-associated pharmacokinetic changes and drug-drug interactions between isoniazid and efavirenz in pregnant women. Eight hundred forty-seven women received isoniazid for 28 weeks, either during pregnancy or at 12 weeks postpartum, and 786 women received efavirenz. After adjusting for NAT2 and CYP2B6 genotype and weight, pregnancy increased isoniazid and efavirenz clearance by 26% and 15%, respectively. Isoniazid decreased efavirenz clearance by 7% in CYP2B6 normal metabolizers and 13% in slow and intermediate metabolizers. Overall, both isoniazid and efavirenz exposures were reduced during pregnancy, but the main determinants of drug concentration were NAT2 and CYP2B6 genotypes, which resulted in a five-fold difference for both drugs between rapid and slow metabolizers.

Pharmacokinetics and safety of early nevirapine-based antiretroviral therapy for neonates at high risk for perinatal HIV infection: a phase 1/2 proof of concept study.

BACKGROUND: With increasing intention to treat HIV as early as possible, evidence to confirm the safety and therapeutic drug concentrations of a nevirapine-based antiretroviral regimen in the early neonatal period is needed. This study aims to establish dosing of nevirapine for very early treatment of HIV-exposed neonates at high risk of HIV acquisition. METHODS: IMPAACT P1115 is a multinational phase 1/2 proof-of-concept study in which presumptive treatment for in-utero HIV infection is initiated within 48 h of birth in HIV-exposed neonates at high risk of HIV acquisition. Participants were neonates who were at least 34 weeks gestational age at birth and enrolled within 48 h of birth, born to women with presumed or confirmed HIV infection who had not received antiretrovirals during this pregnancy. The regimen consisted of two nucleoside reverse transcriptase inhibitors plus nevirapine dosed at 6 mg/kg twice daily for term neonates (≥37 weeks gestational age) or 4 mg/kg twice daily for 1 week and 6 mg/kg twice daily thereafter for preterm neonates (34 to <37 weeks gestational age). Here, we report the secondary outcomes of the study: nevirapine exposures in study weeks 1 and 2 and treatment-associated grade 3 or 4 adverse events at least possibly related to study treatment up to study week 4. A population pharmacokinetic model to assess nevirapine exposure was developed from dried blood spot and plasma nevirapine concentrations at study weeks 1 and 2. Nevirapine exposure was assessed in all patients with available blood samples and safety was assessed in all participants. This trial is registered at ClinicalTrials.gov (NCT02140255). FINDINGS: Between Jan 23, 2015, and Sept 4, 2017, 438 neonates were enrolled and included in analyses; 36 had in-utero HIV infection and 389 (89%) were born at term. Neonates without confirmed in-utero HIV infection received nevirapine for a median of 13 days (IQR 7-14). Measured dried blood spot nevirapine concentrations were higher than the minimum HIV treatment target (3 µg/mL) in 314 (90%, 95% CI 86-93) of 349 neonates at week 1 and 174 (87%, 81-91) of 201 at week 2. In Monte-Carlo simulations, week 1 nevirapine concentrations exceeded 3 µg/mL in 80% of term neonates and 82% of preterm neonates. DAIDS grade 3 or 4 adverse events at least possibly related to antiretrovirals occurred in 30 (7%, 95% CI 5-10) of 438 infants but did not lead to nevirapine cessation in any neonates; neutropenia (25 [6%] neonates) and anaemia (six [1%]) were most common. INTERPRETATION: Nevirapine at the dose studied was confirmed to be safe and provides therapeutic exposure concentrations. These data support nevirapine as a component of presumptive HIV treatment in high-risk neonates. FUNDING: National Institute of Allergy and Infectious Diseases, Eunice Kennedy Shriver National Institute of Child Health and Human Development, and the National Institute of Mental Health.

Effect of Pregnancy and Concomitant Antiretrovirals on the Pharmacokinetics of Tenofovir in Women With HIV Receiving Tenofovir Disoproxil Fumarate-Based Antiretroviral Therapy Versus Women With HBV Receiving Tenofovir Disoproxil Fumarate Monotherapy.

Tenofovir disoproxil fumarate (TDF) is recommended as part of antiretroviral therapy (ART) for pregnant women with HIV and as monotherapy for pregnant women with hepatitis B virus (HBV) monoinfection at high risk of transmitting infection to their infants. Tenofovir (TFV) plasma exposures are reduced during pregnancy; however, concomitant antiretrovirals and the viral infection itself can also influence TFV pharmacokinetics. Our aim was to compare TFV pharmacokinetics in pregnant women receiving TDF-based ART, with or without a ritonavir-boosted protease inhibitor (r/PI), to pregnant women with HBV receiving TDF monotherapy. Non-r/PI regimens were primarily integrase strand transfer inhibitors or nonnucleoside reverse transcriptase inhibitor-based regimens. Data were combined from a pharmacokinetic study of pregnant women with HIV on ART (PANNA), and a study assessing TFV pharmacokinetics in pregnant women with HBV (iTAP). A total of 196 pregnant women, 59 with HIV (32 receiving r/PIs) and 137 with HBV monoinfection were included. Intraindividual TFV area under the plasma concentration-time curve from time 0 to 24 hours was 25%, 26%, and 21% lower during the third trimester compared to 1 month postpartum in women with HIV using TDF and an r/PI or TDF and non-r/PI and women with HBV receiving TDF monotherapy, respectively. TFV area under the plasma concentration-time curve from time 0 to 24 hours was similar in pregnant women receiving non-r/PI to pregnant women with HBV receiving TDF monotherapy (1.84 vs 1.86 µg • h/mL); however, pregnant women receiving TDF with an r/PI had higher exposures (2.41 µg • h/mL; P < .01). Pregnancy reduces TFV exposure and the relative size was not impacted by concomitant antiretroviral drugs or viral infection, but a drug-drug interaction between TDF and r/PI remains during pregnancy, leading to higher exposures than those on TDF and non-r/PI or TDF monotherapy.

Non-nucleoside reverse transcriptase inhibitors (NNRTIs): a brief overview of clinically approved drugs and combination regimens.

The non-nucleoside reverse transcriptase inhibitors (NNRTIs) are allosteric inhibitors of HIV-1 reverse transcriptase and are classified into generations depending on their discovery and resistance profiles. The NNRTIs are used in combination regimens with antiretroviral agents that target two or more enzymes in the viral life cycle. The combination regimens usually include a backbone of two nucleoside or nucleotide reverse transcriptase inhibitors and a third core agent among the NNRTIs or protease inhibitors. The combination regimens are maintained over long durations and consequently lead to long-term problems, including toxicity, drug-drug interactions, and increasing costs. This brief overview summarizes the pharmacokinetic profiles for NNRTIs and NNRTI-based combination regimens.