The Effect of Single and Multiple Doses of Rifampin on the Pharmacokinetics of Doravirine in Healthy Subjects

Clinical considerations and pharmacokinetic interactions between HIV and tuberculosis therapeutics

INTRODUCTION

Tuberculosis(TB) is a leading infectious diseases cause of mortality worldwide,especially for people living with human immunodeficiency virus(PLWH). Treating TB in PLWH can be challenging due to numerous druginteractions.

AREASCOVERED

Thisreview discusses drug interactions between antitubercular andantiretroviral drugs. Due to its clinical importance, initiation ofantiretroviral therapy in patients requiring TB treatment isdiscussed. Special focus is placed on the rifamycin class, as itaccounts for the majority of interactions. Clinically relevantguidance is provided on how to manage these interactions. Anadditional section on utilizing therapeutic drug monitoring (TDM) tooptimize drug exposure and minimize toxicities is included.

EXPERTOPINION

Antitubercularand antiretroviral coadministration can be successfully managed. TDMcan be used to optimize drug exposure and minimize toxicity risk. Asnew TB and HIV drugs are discovered, additional research will beneeded to assess for clinically relevant drug interactions.

Clinical Relevance of Drug Interactions in People Living with Human Immunodeficiency Virus on Antiretroviral Therapy-Update 2022: Systematic Review

BACKGROUND

The clinical outcomes of antiretroviral drugs may be modified through drug interactions; thus, it is important to update the drug interactions in people living with HIV (PLHIV).

AIM

To update clinically relevant drug interactions in PLHIV on antiretroviral therapy with novel drug interactions published from 2017 to 2022.

METHODS

A systematic review in Medline/PubMed database from July 2017 to December 2022 using the Mesh terms antiretroviral agents and drug interactions or herb-drug interactions or food-drug interactions. Publications with drug interactions in humans, in English or Spanish, and with full-text access were retrieved. The clinical relevance of drug interactions was grouped into five levels according to the gravity and probability of occurrence.

RESULTS

A total of 366 articles were identified, with 219 (including 87 citation lists) were included, which allowed for the identification of 471 drug interaction pairs; among them, 291 were systematically reported for the first time. In total 42 (14.4%) and 137 (47.1%) were level one and two, respectively, and 233 (80.1%) pairs were explained with the pharmacokinetic mechanism. Among these 291 pairs, protease inhibitors (PIs) and ritonavir/cobicistat-boosted PIs, as well as integrase strand transfer inhibitors (InSTIs), with 70 (24.1%) and 65 (22.3%) drug interaction pairs of levels one and two, respectively, were more frequent.

CONCLUSIONS

In PLHIV on antiretroviral therapy, we identify 291 drug interaction pairs systematically reported for the first time, with 179 (61.5%) being assessed as clinically relevant (levels one and two). The pharmacokinetic mechanism was the most frequently identified. PIs, ritonavir/cobicistat-boosted PIs, and InSTIs were the antiretroviral groups with the highest number of clinically relevant drug interaction pairs (levels one and two).

HIV/Tuberculosis Coinfection in Pregnancy and the Postpartum Period

The convergence of Human Immunodeficiency Virus (HIV) and tuberculosis (TB) represents a considerable global public health challenge. The concurrent infection of HIV and TB in pregnant women not only intensifies the transmission of HIV from mother to fetus but also engenders adverse outcomes for maternal health, pregnancy, and infant well-being, necessitating the implementation of integrated strategies to effectively address and manage both diseases. In this article, we review the pathophysiology, clinical presentation, treatment, and management of HIV/TB coinfection during pregnancy, the postpartum period, and lactation and highlight the differences compared to the general population.

Comprehensive in vitro analysis evaluating the variable drug-drug interaction risk of rifampicin compared to rifabutin

Compared to rifampicin (600 mg/day), standard doses of rifabutin (300 mg/day) have a lower risk of drug-drug interactions due to induction of cytochrome P450 3A4 (CYP3A4) or P-glycoprotein (Pgp/ABCB1) mediated by the pregnane X receptor (PXR). However, clinical comparisons with equal rifamycin doses or in vitro experiments respecting actual intracellular concentrations are lacking. Thus, the genuine pharmacological differences and the potential molecular mechanisms of the discordant perpetrator effects are unknown. Consequently, the cellular uptake kinetics (mass spectrometry), PXR activation (luciferase reporter gene assays), and impact on CYP3A4 and Pgp/ABCB1 expression and activity (polymerase chain reaction, enzymatic assays, flow cytometry) were evaluated in LS180 cells after treatment with different rifampicin or rifabutin concentrations for variable exposure times and eventually normalized to actual intracellular concentrations. In addition, inhibitory effects on CYP3A4 and Pgp activities were investigated. While rifampicin is poorly taken up by LS180 cells, it strongly activates PXR and leads to enhanced expression and activity of CYP3A4 and Pgp. In contrast, rifabutin is a significantly less potent and less efficient PXR activator and gene inducer, despite sixfold to eightfold higher intracellular accumulation. Finally, rifabutin is a potent inhibitor of Pgp (IC50 = 0.3 µM) compared to rifampicin (IC50 = 12.9 µM). Together, rifampicin and rifabutin significantly differ by their effects on the regulation and function of CYP3A4 and Pgp, even when controlled for intracellular concentrations. Rifabutin's concurrent Pgp inhibitory action might partly compensate the inducing effects, explaining its weaker clinical perpetrator characteristics.

Infant Exposure to Antituberculosis Drugs via Breast Milk and Assessment of Potential Adverse Effects in Breastfed Infants: Critical Review of Data

Infants of mothers treated for tuberculosis might be exposed to drugs via breast milk. The existing information on the exposure of breastfed infants lacks a critical review of the published data. We aimed to evaluate the quality of the existing data on antituberculosis (anti-TB) drug concentrations in the plasma and milk as a methodologically sound basis for the potential risk of breastfeeding under therapy. We performed a systematic search in PubMed for bedaquiline, clofazimine, cycloserine/terizidone, levofloxacin, linezolid, pretomanid/pa824, pyrazinamide, streptomycin, ethambutol, rifampicin and isoniazid, supplemented with update references found in LactMed^®. We calculated the external infant exposure (EID) for each drug and compared it with the recommended WHO dose for infants (relative external infant dose) and assessed their potential to elicit adverse effects in the breastfed infant. Breast milk concentration data were mainly not satisfactory to properly estimate the EID. Most of the studies suffer from limitations in the sample collection, quantity, timing and study design. Infant plasma concentrations are extremely scarce and very little data exist documenting the clinical outcome in exposed infants. Concerns for potential adverse effects in breastfed infants could be ruled out for bedaquiline, cycloserine/terizidone, linezolid and pyrazinamide. Adequate studies should be performed covering the scenario in treated mothers, breast milk and infants.

Characterizing complex and competing drug-drug interactions between the antiviral regimen of glecaprevir and pibrentasvir with rifampin or carbamazepine

The fixed-dose combination of the direct acting antivirals glecaprevir (GLE) and pibrentasvir (PIB) is an oral, once-daily treatment for all six major genotypes of chronic hepatitis C virus infection. A single and multiple-dose rifampin study (N = 12) and a carbamazepine study (N = 12) were conducted in healthy subjects to evaluate the effects of CYP3A/P-gp induction and OATP inhibition on the pharmacokinetics of GLE and PIB. In study 1, GLE 300 mg + PIB 120 mg was administered as a single dose either alone, after single and multiple daily doses of rifampin 600 mg, or 24 h after the last rifampin dose. In study 2, GLE 300 mg + PIB 120 mg was administered as a single dose either alone or after multiple doses of carbamazepine 200 mg. Relative to GLE + PIB alone, exposure of GLE was significantly increased by the first co-administered rifampin dose due to OATP inhibition, significantly decreased 24 h after the last rifampin dose due to CYP3A/P-gp induction, and slightly increased when co-administered with steady-state rifampin due to a combination of inhibition and induction forces. Exposure of PIB was not affected when co-administered with the first rifampin dose but was significantly decreased with steady-state rifampin co-administration, or 24 h after the last rifampin dose due to P-gp induction. Carbamazepine significantly decreased GLE and PIB exposure, mainly attributed to P-gp induction. The regimens tested were generally well-tolerated by the subjects and no new safety issues were identified.

Treatment of Tuberculosis and the Drug Interactions Associated With HIV-TB Co-Infection Treatment

Tuberculosis (TB) is a communicable disease that is a major source of illness, one of the ten causes of mortality worldwide, and the largest cause of death from a single infectious agent Mycobacterium tuberculosis. HIV infection and TB are a fatal combination, with each speeding up the progression of the other. Barriers to integrated treatment as well as safety concerns on the co-management of HIV- TB co-infection do exist. Many HIV TB co-infected people require concomitant anti-retroviral therapy (ART) and anti-TB medication, which increases survival but also introduces certain management issues, such as drug interactions, combined drug toxicities, and TB immune reconstitution inflammatory syndrome which has been reviewed here. In spite of considerable pharmacokinetic interactions between antiretrovirals and antitubercular drugs, when the pharmacological characteristics of drugs are known and appropriate combination regimens, dosing, and timing of initiation are used, adequate clinical response of both infections can be achieved with an acceptable safety profile. To avoid undesirable drug interactions and side effects in patients, anti TB treatment and ART must be closely monitored. To reduce TB-related mortality among HIV-TB co-infected patients, ART and ATT (Anti Tuberculosis Treatment) outcomes must improve. Clinical practise should prioritise strategies to promote adherence, such as reducing treatment duration, monitoring and treating adverse events, and improving treatment success rates, to reduce the mortality risk of HIV-TB co-infection.

Doravirine: its role in HIV treatment

PURPOSE OF REVIEW

We reviewed evidence concerning the novel nonnucleoside reverse transcriptase inhibitor doravirine, aiming to identify situations where it may be selected in preference to integrase inhibitors.

RECENT FINDINGS

Doravirine is licenced for the treatment of HIV-1 in North America and Europe. In two multicentre randomized controlled trials, noninferiority with comparator drugs efavirenz and darunavir/ritonavir was observed at 96 weeks. Doravirine is associated with a lower incidence of neuropsychiatric side effects relative to efavirenz, and favourable lipid changes relative to darunavir over 96 weeks. A lower incidence of weight gain, relative to indirect comparisons with integrase inhibitors, was observed. Doravirine has a high genetic barrier to resistance with retained activity in the presence of single NNRTI mutations K103N, Y181C and G190A. Primary drug resistance is infrequent and may be higher in South Africa relative to European populations. Doravirine may be used in renal or hepatic impairment and has a low potential for drug-drug interactions.

SUMMARY

Doravirine is a well tolerated and effective agent in ART-naive patients. Direct comparison with integrase inhibitors, and evidence on the outcomes of treatment with doravirine in the presence of prior NNRTI experience are required to better elucidate which patients will benefit most from doravirine therapy.

Pharmacokinetic interactions of modern antiretroviral therapy

Drug--drug interactions (DDIs) have been a clinical challenge in HIV medicine for over two decades. The newer antiretroviral drugs (ARTs) have significantly fewer DDIs than protease inhibitors and boosted integrase inhibitors (INSTIs). The lower propensity of such newer antiretrovirals (e.g. unboosted integrase inhibitors; doravirine) to cause DDIs, has been largely offset by the ageing cohort of patients with multiple comorbidities, who are taking multiple chronic medicines. Furthermore, the introduction of newly marketed drugs into clinical practice needs to be closely monitored, as the new drugs may be perpetrators of DDIs, leading to a potential change in the efficacy or toxicity of the coadministered antiretrovirals.

A Phase 1 Study to Evaluate the Drug Interaction Between Islatravir (MK-8591) and Doravirine in Adults Without HIV

BACKGROUND AND OBJECTIVES

Islatravir (MK-8591) is a novel nucleoside analogue in development for the treatment and prevention of HIV-1 infection. Doravirine is a non-nucleoside reverse transcriptase inhibitor indicated for the treatment of HIV-1 infection. This study evaluated the pharmacokinetics, safety, and tolerability of islatravir and doravirine coadministration in a double-blind, placebo-controlled, randomized, fixed-sequence study.

METHODS

Adult participants without HIV infection were administered oral doravirine 100 mg (n = 10) or placebo (n = 4) once daily (QD) for 5 days, immediately followed by oral islatravir 2.25 mg (n = 10) or placebo QD (n = 4) for 14 days; islatravir 2.25 mg and doravirine 100 mg QD, or placebo QD, were then coadministered for 5 days. Pharmacokinetic and safety data were collected.

RESULTS

Doravirine geometric least-squares mean ratios (90% confidence intervals (CIs)) of (doravirine + islatravir)/doravirine for the area under the plasma drug concentration-time curve over 24 h (AUC0-24h), maximum plasma concentration (Cmax), and plasma concentration at 24 h post-dose (C24h) were not meaningfully impacted. Islatravir geometric least-squares mean ratios (90% CI) of (islatravir + doravirine)/islatravir for AUC0-24h and Cmax were both close to unity, 1.06 (1.01, 1.12) and 1.08 (0.91, 1.27), respectively. All study regimens were generally well tolerated.

CONCLUSION

These results indicate that coadministration of islatravir and doravirine had no clinically meaningful effect on the pharmacokinetics of either drug, and support further clinical investigation of islatravir in combination with doravirine for the treatment of HIV-1 infection.

Mechanisms underlying of antiretroviral drugs in different cellular reservoirs with a focus on macrophages

Ongoing with current combinations of antiretroviral drugs for the treatment of Human Immunodeficiency Virus (HIV) infection can successfully maintain long-term suppression of HIV-1 replication in plasma. Still, none of these therapies is capable of extinguishing the virus from the long-lived cellular reservoir, including monocyte-derived macrophages (MDM), that means the principal obstacle to HIV cure. MDM are widely distributed in all tissues and organs, including central system nervous (CNS) where they represent the most frequent HIV-infected cells that means the principal obstacle to HIV cure. Current FDA-approved antiretroviral drugs target viral reverse transcriptase, protease, integrase, and entry processes (coreceptor or fusion blockade). It is desirable to continue to develop new antiretrovirals directed against alternative targets in the virus lifecycle in order to further optimize therapeutic options, overcome resistance to existing medications, and potentially contribute to the elimination of viral reservoirs.This review provides a comprehensive overview of the activity of antiretroviral drugs (classical and upcoming) in monocytes-derived macrophages (MDM). Defining the antiviral activity of these drugs in this important cellular HIV-1 reservoir provides crucial hints about their efficacy in HIV-1 infected patients.

Pharmacokinetics of antiretroviral and tuberculosis drugs in children with HIV/TB co-infection: a systematic review

INTRODUCTION

Management 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.

METHODS

We 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.

RESULTS

In 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 <3 years of age. Super-boosted lopinavir/ritonavir (ratio 1:1) resulted in adequate lopinavir trough concentrations during rifampicin co-administration. Double-dosed raltegravir can be given with rifampicin 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.

CONCLUSIONS

Whereas integrase inhibitors seem favourable in older children, there are limited options for ART in young children (<3 years) receiving rifampicin-based TB therapy. The PK of TB drugs in HIV-infected children warrants further research.

Clinical Pharmacokinetics of the Novel HIV-1 Non-Nucleoside Reverse Transcriptase Inhibitor Doravirine: An Assessment of the Effect of Patient Characteristics and Drug-Drug Interactions

Doravirine (MK-1439) is a novel non-nucleoside reverse transcriptase inhibitor indicated for the combination treatment of human immunodeficiency virus type-1 (HIV-1) infection. The recommended dose is 100 mg once daily. This review summarizes the pharmacokinetics of doravirine, the influence of intrinsic factors, and its drug-drug interaction (DDI) profile. Following oral administration, doravirine is rapidly absorbed (median time to maximum plasma concentration, 1-4 h) and undergoes cytochrome P450 (CYP)3A-mediated oxidative metabolism. Steady-state geometric means for AUC0-24, C24, and Cmax in individuals with HIV-1 following administration of doravirine 100 mg once daily are 37.8 μM·h, 930 nM, and 2260 nM, respectively. Age, gender, severe renal impairment, and moderate hepatic impairment have no clinically meaningful effect on doravirine pharmacokinetics, and there is limited potential for DDIs. No dose adjustment is necessary when doravirine is co-administered with strong CYP3A inhibitors. However, doravirine is contraindicated with strong CYP3A inducers (e.g., rifampin), and dose adjustment of doravirine is recommended for co-administration with the moderate CYP3A inducer, rifabutin. Included in this review are clinical trial data from phase I pharmacokinetic trials, including DDI trials and trials in participants with renal and hepatic disease but without HIV-1 infection (N = 326), as well as phase I, II, and III safety and efficacy trials in participants living with HIV-1 (N = 991). Based on these data, the pharmacokinetic profile of doravirine supports its use in diverse populations living with HIV-1 and allows co-administration with various antiretroviral agents and treatments for commonly occurring co-morbidities.

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.

Clinical Pharmacodynamics, Pharmacokinetics, and Drug Interaction Profile of Doravirine

Doravirine is a novel non-nucleoside reverse transcriptase inhibitor (NNRTI) that has demonstrated good efficacy, tolerability, and safety for the treatment of patients with human immunodeficiency virus (HIV)-1 infection in phase III clinical trials. Doravirine achieved non-inferiority when compared with efavirenz- and darunavir/ritonavir-based regimens. Fewer adverse effects, including neuropsychiatric effects were observed with doravirine compared with efavirenz. Key pharmacodynamic and pharmacokinetic characteristics as well as drug-drug interactions and the resistance profile were assessed in this clinical review. Doravirine is a pyridinone NNRTI with potent antiviral activity against wild-type HIV-1 virus and common NNRTI variants. Studies in healthy volunteers and HIV-infected individuals have shown that doravirine has a favorable pharmacokinetic profile for once-daily dosing, with an elimination half-life of around 15 h, median time to maximum plasma concentrations of 1-4 h, and time to steady-state concentration of 7 days. The pharmacokinetics of doravirine are not greatly influenced by sex, age, race, or hepatic impairment. Although no dose adjustment is required for doravirine in renal impairment when given as a single tablet, the fixed-dose combination tablet of doravirine/lamivudine/tenofovir disoproxil fumarate is not recommended in patients with a creatinine clearance of < 50 mL/min. Doravirine has a low potential for drug-drug interactions and does not impact on the pharmacokinetics of other drugs. However, it is metabolized via cytochrome P450 (CYP) 3A enzymes and is thus susceptible to interactions with CYP3A inhibitors and inducers. Strong CYP3A inhibitors can significantly increase doravirine exposure; however, this is not considered to be clinically relevant. Conversely, strong CYP3A inducers, such as rifampin, are contraindicated with doravirine owing to a significant reduction in exposure with potential for impaired virological efficacy. Moderate CYP3A inducers, such as rifabutin, may be co-administered if the doravirine dose is increased to 100 mg twice daily. Doravirine has a unique resistance profile and has demonstrated in vitro activity against some of the most common, clinically relevant NNRTI-resistant mutations. Prevalence of baseline NNRTI resistance to doravirine appears to be low in treatment-naïve cohorts. Further data on the efficacy of doravirine in patients with previous treatment experience and/or transmitted NNRTI resistance are required to further inform its place in the current armamentarium of drugs for the treatment of HIV infection.

Application of a microdosed cocktail of 3 oral factor Xa inhibitors to study drug-drug interactions with different perpetrator drugs

AIMS

Using 3 different perpetrators the impact of voriconazole, cobicistat and rifampicin (single dose), we evaluated the suitability of a microdose cocktail of factor Xa inhibitors (FXaI; rivaroxaban, apixaban and edoxaban; 100 μg in total) to study drug-drug interactions.

METHODS

Three cohorts of 6 healthy volunteers received 2 treatments with microdoses of rivaroxaban, apixaban and edoxaban alone and with coadministration of 1 of the perpetrators. Plasma and urine concentrations of microdosed apixaban, edoxaban and rivaroxaban were quantified using a validated ultra-performance liquid chromatography-tandem mass spectrometry with a lower limit of quantification of 2.5 pg/mL.

RESULTS

Voriconazole caused only a minor interaction with apixaban and rivaroxaban, none with edoxaban. Cobicistat significantly increased exposure of all 3 FXaI with area under the plasma concentration-time curve ratios of 1.67 (apixaban), 1.74 (edoxaban) and 2.0 (rivaroxaban). A single dose of rifampicin decreased the volume of distribution and elimination half-life of all 3 FXaI.

CONCLUSIONS

The microdosed FXaI cocktail approach is able to generate drug interaction data and can help elucidating the mechanism involved in the clearance of the different victim drugs. This is a safe approach to concurrently study drug-drug interactions with a drug class. (EudraCT 2016-003024-23).

No meaningful drug interactions with doravirine, lamivudine and tenofovir disoproxil fumarate coadministration

BACKGROUND

Doravirine (DOR) is a novel non-nucleoside reverse transcriptase inhibitor available as a single tablet and a three-drug combination with lamivudine (3TC) and tenofovir disoproxil fumarate (TDF) to treat HIV-1 infection. These analyses assessed pharmacokinetic (PK) interactions with coadministration.

METHODS

Two trials were conducted. Study 1: two-period, fixed-sequence; eight healthy participants; Period 1, DOR 100 mg followed by ≥7-day washout; Period 2, TDF 300 mg once daily for 18 days, coadministration of DOR 100 mg on day 14. Study 2: three-period, crossover, 15 healthy participants; Treatment A, DOR 100 mg; Treatment B, 3TC 300 mg + TDF 300 mg; Treatment C, DOR 100 mg + 3TC 300 mg + TDF 300 mg; ≥7-day washout between periods.

RESULTS

Study 1: geometric mean ratios (GMRs; 90% confidence interval [CI]) of DOR area under the concentration-time curve from time 0 extrapolated to infinity (AUC_0-∞) and observed plasma concentrations at 24 h post-dose (C_{24 h}; DOR+TDF/DOR) were 0.95 (0.80, 1.12) and 0.94 (0.78, 1.12), respectively. Study 2: GMRs (90% CI) of DOR AUC_0-∞ and C_{24 h} (DOR+3TC+TDF/DOR) were 0.96 (0.87, 1.06) and 0.94 (0.83, 1.06), respectively. GMRs (90% CI) of 3TC and tenofovir AUC_0-∞ (DOR+3TC+TDF/3TC+TDF) were 0.94 (0.88, 1.00) and 1.11 (0.97, 1.28), respectively. Study drugs were generally well tolerated.

CONCLUSIONS

Multiple doses of TDF did not have a clinically meaningful effect on DOR PK. The PK of DOR were similar when administered alone or in combination with 3TC and TDF. DOR had no meaningful effect on the PK of 3TC and tenofovir.

Doravirine dose selection and 96-week safety and efficacy versus efavirenz in antiretroviral therapy-naive adults with HIV-1 infection in a Phase IIb trial

BACKGROUND

The safety and efficacy of doravirine were compared with that of efavirenz as initial treatment of adults living with HIV-1 infection (NCT01632345).

METHODS

A Phase IIb double-blind trial with participants stratified by screening HIV-1 RNA (≤ or >100,000 copies/ml) and randomized 1:1:1:1:1 to receive once-daily doravirine (25, 50, 100 or 200 mg) or efavirenz 600 mg (Part I) for up to 96 weeks, with open-label tenofovir disoproxil fumarate 300 mg/emtricitabine 200 mg (TDF/FTC). After dose selection at week 24, doravirine 100 mg was provided to participants receiving the other doses of doravirine and additional participants were randomized 1:1 to receive once-daily doravirine 100 mg or efavirenz 600 mg for 96 weeks with TDF/FTC (Part II). Primary outcomes were the proportion of participants with HIV-1 RNA <40 copies/ml at week 24, and central nervous system (CNS) adverse events (AEs) by weeks 8 and 24 (Parts I+II combined).

RESULTS

210 and 132 participants were randomized in Parts I and II, respectively, and 216 (108 on doravirine 100 mg, 108 on efavirenz) were evaluable for Parts I+II combined. At week 24, the proportion of participants with HIV-1 RNA <40 copies/ml was 72.9% for doravirine 100 mg and 73.1% for efavirenz (difference -0.5 [95% CI -12.3, 11.2]). In addition, CNS AEs were reported by 26.9% and 47.2% of doravirine and efavirenz recipients, respectively (difference -20.4 [95% CI -32.6, -7.5]; P=0.002).

CONCLUSIONS

Doravirine 100 mg with TDF/FTC demonstrated similar antiretroviral activity and superior CNS safety compared with efavirenz 600 mg with TDF/FTC.

Doravirine and Its Potential in the Treatment of HIV: An Evidence-Based Review of the Emerging Data

The utility of doravirine in the management of HIV-1 infection is approved for use in patients who are antiretroviral-naïve as well as patients who have achieved stable virologic suppression and are interested in replacing their current antiretroviral therapy. The role of doravirine continues to evolve as data emerges on the potential for new combination therapy with the investigational agent, islatravir, as well as a potential strategy to minimize post-marketing safety concerns with recommended first-line agents, such as integrase inhibitors. The goal of this review is to assess recent and emerging data on the non-nucleoside reverse transcriptase inhibitor, doravirine.

Twice-Daily Doravirine Overcomes the Interaction Effect from Once-Weekly Rifapentine and Isoniazid in Healthy Volunteers

Doravirine (DOR) is a non‐nucleoside reverse transcriptase inhibitor indicated for the treatment of HIV‐1. Its use in combination with rifapentine (RPT), an antituberculosis (TB) antibiotic, may reduce the exposure of DOR compromising viral suppression in those living with HIV‐1 co‐infected with TB. We conducted a prospective, phase I, open label, two‐period, fixed sequence, drug interaction study to evaluate the effect of once‐weekly RPT and isoniazid (INH) on the pharmacokinetics (PKs) of DOR in healthy volunteers. DOR 100 mg was administered alone twice‐daily for 4 days in period 1. In period 2, once‐weekly RPT + INH were co‐administered with multiple doses of DOR 100 mg twice‐daily for study days 7, 14, and 21. Plasma was obtained for DOR PKs when given alone and co‐administered with RPT + INH. Eleven healthy volunteers enrolled and completed the study. The geometric mean ratios and 90% confidence intervals for DOR area under the concentration‐time curve from zero to 12 hours (AUC_0–12) and C₁₂ in the presence of RPT + INH compared with DOR alone were 0.71 (0.60–0.85) and 0.69 (0.54–0.89), respectively. Although exposures were moderately reduced in the presence of RPT + INH, trough DOR values were within the concentration range associated with virological suppression. These results demonstrate that a modest decrease in DOR exposure would unlikely be clinically relevant in a virally suppressed patient co‐administered once‐weekly RPT + INH.

Doravirine/Lamivudine/Tenofovir Disoproxil Fumarate is Non-inferior to Efavirenz/Emtricitabine/Tenofovir Disoproxil Fumarate in Treatment-naive Adults With Human Immunodeficiency Virus-1 Infection: Week 48 Results of the DRIVE-AHEAD Trial

Background

Doravirine (DOR), a novel non-nucleoside reverse-transcriptase inhibitor (NNRTI), is active against wild-type Human Immunodeficiency Virus (HIV)-1 and the most common NNRTI-resistant variants, and has a favorable and unique in vitro resistance profile.

Methods

DRIVE-AHEAD is a phase 3, double-blind, non-inferiority trial. Antiretroviral treatment–naive adults with ≥1000 HIV-1 RNA copies/mL were randomized (1:1) to once-daily, fixed-dose DOR at 100 mg, lamivudine at 300 mg, and tenofovir disoproxil fumarate (TDF) at 300 mg (DOR/3TC/TDF) or to efavirenz at 600 mg, emtricitabine at 200 mg, and TDF at 300 mg (EFV/FTC/TDF) for 96 weeks. The primary efficacy endpoint was the proportion of participants with <50 HIV-1 RNA copies/mL at week 48 (Food and Drug Administration snapshot approach; non-inferiority margin 10%).

Results

Of the 734 participants randomized, 728 were treated (364 per group) and included in the analyses. At week 48, 84.3% (307/364) of DOR/3TC/TDF recipients and 80.8% (294/364) of EFV/FTC/TDF recipients achieved <50 HIV-1 RNA copies/mL (difference 3.5%, 95% CI, -2.0, 9.0). DOR/3TC/TDF recipients had significantly lower rates of dizziness (8.8% vs 37.1%), sleep disorders/disturbances (12.1% vs 25.2%), and altered sensorium (4.4% vs 8.2%) than EFV/FTC/TDF recipients. Mean changes in fasting low-density lipoprotein cholesterol (LDL-C) and non-high-density lipoprotein cholesterol (non-HDL-C) were significantly different between DOR/3TC/TDF and EFV/FTC/TDF (−1.6 vs +8.7 mg/dL and −3.8 vs +13.3 mg/dL, respectively).

Conclusions

In HIV-1 treatment-naive adults, DOR/3TC/TDF demonstrated non-inferior efficacy to EFV/FTC/TDF at week 48 and was well tolerated, with significantly fewer neuropsychiatric events and minimal changes in LDL-C and non–HDL-C compared with EFV/FTC/TDF.

Clinical Trials Registration

NCT02403674

Safety implications of combined antiretroviral and anti-tuberculosis drugs

Introduction: Antiretroviral and anti-tuberculosis (TB) drugs are often co-administered in people living with HIV (PLWH). Early initiation of antiretroviral therapy (ART) during TB treatment improves survival in patients with advanced HIV disease. However, safety concerns related to clinically significant changes in drug exposure resulting from drug-drug interactions, development of overlapping toxicities and specific challenges related to co-administration during pregnancy represent barriers to successful combined treatment for HIV and TB.Areas covered: Pharmacokinetic interactions of different classes of ART when combined with anti-TB drugs used for sensitive-, drug-resistant (DR) and latent TB are discussed. Overlapping drug toxicities, implications of immune reconstitution inflammatory syndrome (IRIS), safety in pregnancy and research gaps are also explored.Expert opinion: New antiretroviral and anti-tuberculosis drugs have been recently introduced and international guidelines updated. A number of effective molecules and clinical data are now available to build treatment regimens for PLWH with latent or active TB. Adopting a systematic approach that also takes into account the need for individualized variations based on the available evidence is the key to successfully integrate ART and TB treatment and improve treatment outcomes.

Effect of treatment period with LC478, a disubstituted adamantayl derivative, on P-glycoprotein inhibition: its application to increase docetaxel absorption in rats

1. Treatment periods of P-glycoprotein (P-gp) inhibitors have revealed different efficacies. We have previously reported dose-dependent inhibition of P-gp in single-treatment with LC478. However, whether repeated treatment with LC478 can inhibit P-gp even at its ineffective single-treatment dose remains unknown. 2. Therefore, the purpose of this study was to assess the effect of repeated treatment (i.e., 7-day treatment) with LC478 on P-gp known to affect docetaxel bioavailability in rats. Effects of LC478 on P-gp mediated efflux and expression in MDCK-MDR1 cells, P-gp ATPase activity, and binding site with P-gp were evaluated.3. The 7-day treatment with LC478 increased docetaxel absorption via intestinal P-gp inhibition in rats. Intestinal concentrations of LC478 were 8.31-10.3 μM in rats after 7-day treatment of LC478. These concentrations were close to 10 μM that reduced P-gp mediated docetaxel efflux and P-gp expression in MDCK-MDR1 cells. Considering that intestinal LC478 concentrations after 1-day treatment were 2.68-4.19 μM, higher LC478 concentrations after 7-day treatment might have driven P-gp inhibition and increased docetaxel absorption. LC478 might competitively inhibit P-gp considering its stimulated ATPase activity and its binding site with nucleotide binding domain of P-gp. 4. Therefore, repeated treatment with LC478 can determine its feasibility for P-gp inhibition and changing docetaxel bioavailability.

Management of Virologic Failure and HIV Drug Resistance

Approximately 20% of people with HIV in the United States prescribed antiretroviral therapy are not virally suppressed. Thus, optimal management of virologic failure has a critical role in the ability to improve viral suppression rates to improve long-term health outcomes for those infected and to achieve epidemic control. This article discusses the causes of virologic failure, the use of resistance testing to guide management after failure, interpretation and relevance of HIV drug resistance patterns, considerations for selection of second-line and salvage therapies, and management of virologic failure in special populations.

Doravirine: A Return of the NNRTI Class?

Objective: To compare and contrast doravirine (DOR) with other agents in the nonnucleoside reverse transcriptase inhibitor (NNRTI) class, review safety and efficacy data from both completed and ongoing clinical trials, and outline the potential place in therapy of DOR. Data Sources: A literature search using the PubMed database (inception to June 2019) was conducted using the search terms HIV, doravirine, non-nucleoside reverse transcriptase inhibitor, NNRTI, and MK-1439. Study Selection and Data Extraction: Clinical data were limited to those published in the English language from phase 2 or 3 clinical trials. Ongoing trials were identified through ClinicalTrials.gov. Data Synthesis: DOR was approved by the US Food and Drug Administration on the strength of 2 phase 3 randomized, double-blind, noninferiority clinical trials with additional studies currently underway examining its utility in other clinical scenarios. Relevance to Patient Care and Clinical Practice: The role of NNRTIs as part of antiretroviral (ARV) therapy has diminished in recent years given the introduction of more tolerable individual ARV agents and regimens. Despite this, new agents are still needed in the therapeutic arena because treatment failure as well as intolerance can still occur with many first-line therapies. The optimal place in therapy of DOR remains to be defined. Conclusions: DOR is a new NNRTI that represents a potential treatment option for treatment-naïve patients, without many of the previously described untoward effects of the NNRTI class.

Determination of doravirine in human plasma using liquid–liquid extraction and HPLC–MS/MS

Aim: A method to quantitate doravirine (MK-1439) in human plasma has been developed to support human clinical trials designed to evaluate the safety, pharmacokinetics and efficacy of the compound. Methodology & results: The analyte was extracted using liquid–liquid extraction, separated on a reverse phase HPLC column, and detected on an API-4000 mass spectrometer using a Turbo-Ion spray source in positive ionization mode coupled with multiple reaction monitoring mode was used for quantification. The dynamic range for the assay was 0.02–10 ng/ml using 100 μl of human plasma. Conclusion: The assay was found to be sensitive, selective and reproducible and applied to support the doravirine clinical development program.

Doravirine: First Global Approval

Doravirine is a new non-nucleoside reverse transcriptase inhibitor (NNRTI) developed by Merck & Co for the treatment of HIV-1 infection. The drug is approved in the USA both as a single-agent tablet (Pifeltro™) and as a fixed-dose combination tablet with the nucleos(t)ide reverse transcriptase inhibitors lamivudine and tenofovir disoproxil fumarate (Delstrigo™). Each formulation is indicated in the USA for treating HIV-1 infection in adults with no prior antiretroviral treatment, has received a positive opinion in the EU for treating HIV-1 infection in adults without resistance to NNRTIs or (in the case of the fixed-dose combination tablet) lamivudine or tenofovir, and is also under regulatory review for the treatment of HIV-1 infection in Canada. This article summarizes the milestones in the development of doravirine leading to this first approval for the treatment of HIV-1 infection in treatment-naïve adults.

Evaluation of the Pharmacokinetic Interaction Between Doravirine and Methadone

Doravirine is a novel nonnucleoside reverse transcriptase inhibitor indicated for the treatment of HIV type 1 infection. A subset of people living with HIV receives methadone for the treatment of opioid addiction. The current study (NCT02715700) was an open-label, multiple-dose, drug interaction study in participants on a methadone maintenance program to investigate potential drug-drug interactions between doravirine and methadone. Participants received a stable methadone maintenance dose of 20 to 180 mg once daily for 14 days prior to day 1 and remained on their maintenance dose over days 1 through 7. On days 2 through 6, an oral dose of doravirine 100 mg was coadministered. For doravirine and methadone pharmacokinetic analysis, blood samples were collected before dosing through 24 hours after dosing. Fourteen participants were enrolled; all participants completed the study. For R-methadone, geometric least squares mean ratios (90% confidence intervals) for dose-normalized area under the plasma concentration-time curve from time zero to 24 hours, plasma concentration at 24 hours, and maximum plasma concentration ([methadone + doravirine]/methadone alone) were 0.95 (0.90-1.01), 0.95 (0.88-1.03), and 0.98 (0.93-1.03), respectively. For doravirine, based on a comparison with historical data, modest decreases in area under the plasma concentration-time curve from time zero to 24 hours, plasma concentration at 24 hours, and maximum plasma concentration were observed after coadministration of doravirine and methadone; geometric least squares mean ratios ([methadone + doravirine]/doravirine alone [90% confidence intervals]) were 0.74 (0.61-0.90), 0.80 (0.63-1.03), and 0.76 (0.63-0.91), respectively. Coadministration of doravirine and methadone was generally well tolerated. No serious adverse events occurred, and there were no discontinuations. In conclusion, coadministration of methadone and doravirine did not have a clinically meaningful effect on the pharmacokinetic profile of either agent.

Doravirine and the Potential for CYP3A-Mediated Drug-Drug Interactions

Identifying and understanding potential drug-drug interactions (DDIs) are vital for the treatment of human immunodeficiency virus type 1 (HIV-1) infection. This article discusses DDIs between doravirine, a nonnucleoside reverse transcriptase inhibitor (NNRTI), and cytochrome P450 3A (CYP3A) substrates and drugs that modulate CYP3A activity. Consistent with previously published in vitro data and DDI trials with the CYP3A substrates midazolam and atorvastatin, doravirine did not have any meaningful impact on the pharmacokinetics of the CYP3A substrates ethinyl estradiol and levonorgestrel. Coadministration of doravirine with CYP3A inhibitors (ritonavir or ketoconazole) increased doravirine exposure approximately 3-fold. However, these increases were not considered clinically meaningful. Conversely, previously published trials showed that coadministered CYP3A inducers (rifampin and rifabutin) decreased doravirine exposure by 88% and 50%, respectively (K. L. Yee, S. G. Khalilieh, R. I. Sanchez, R. Liu, et al., Clin Drug Investig 37:659-667, 2017 [https://doi.org/10.1007/s40261-017-0513-4]; S. G. Khalilieh, K. L. Yee, R. I. Sanchez, R. Liu, et al., J Clin Pharmacol 58:1044-1052, 2018 [https://doi.org/10.1002/jcph.1103]), while doravirine exposure following prior efavirenz administration led to an initial reduction in doravirine exposure of 62%, but the reduction became less pronounced with time (K. L. Yee, R. I. Sanchez, P. Auger, R. Liu, et al., Antimicrob Agents Chemother 61:e01757-16, 2017 [https://doi.org/10.1128/AAC.01757-16]). Overall, the coadministration of doravirine with CYP3A inhibitors and substrates is, therefore, supported by these data together with efficacy and safety data from clinical trials, while coadministration with strong CYP3A inducers, such as rifampin, cannot be recommended. Concomitant dosing with rifabutin (a CYP3A inducer less potent than rifampin) is acceptable if doravirine dosing is adjusted from once to twice daily; however, the effect of other moderate inducers on doravirine pharmacokinetics is unknown.

Investigation of Pharmacokinetic Interactions between Doravirine and Elbasvir-Grazoprevir and Ledipasvir-Sofosbuvir

Doravirine is a non-nucleoside reverse transcriptase inhibitor for the treatment of human immunodeficiency virus type 1 (HIV-1) infection. Due to the high prevalence of HIV-1 and hepatitis C virus (HCV) coinfection and coadministration of HIV-1 and HCV treatment, potential drug-drug interactions (DDIs) between doravirine and two HCV treatments were investigated in two phase 1 drug interaction trials in healthy participants. Trial 1 investigated the effect of multiple-dose doravirine and elbasvir + grazoprevir coadministration (N = 12), and trial 2 investigated the effect of single-dose doravirine and ledipasvir-sofosbuvir coadministration (N = 14). Doravirine had no clinically relevant effect on the pharmacokinetics of elbasvir, grazoprevir, ledipasvir, sofosbuvir, or the sofosbuvir metabolite GS-331007. Coadministration of elbasvir + grazoprevir with doravirine moderately increased doravirine area under the concentration-time curve from 0 to 24 h (AUC_0-24), maximal concentration (C _max), and concentration 24 h postdose (C ₂₄), with geometric least-squares mean ratio (GMR) with 90% confidence intervals (CI) of 1.56 (1.45, 1.68), 1.41 (1.25, 1.58), and 1.61 (1.45, 1.79), respectively. Doravirine AUC_0-∞, C _max, and C ₂₄ values increased slightly following coadministration with ledipasvir-sofosbuvir (GMR [90% CI] of 1.15 [1.07, 1.24], 1.11 [0.97, 1.27], and 1.24 [1.13, 1.36], respectively). The modest increases in doravirine exposure are not clinically meaningful based on the therapeutic profile of doravirine. Effects are likely secondary to cytochrome P450 3A and P-glycoprotein inhibition by grazoprevir and ledipasvir, respectively. Coadministration of doravirine with elbasvir + grazoprevir or ledipasvir-sofosbuvir was generally well tolerated. Clinically relevant DDIs are not expected to occur between doravirine and elbasvir-grazoprevir or ledipasvir-sofosbuvir at the therapeutic doses.

Doravirine: a review

PURPOSE OF REVIEW

The current review addresses the role of doravirine (DOR), a novel once-daily nonnucleoside reverse transcriptase inhibitor (NNRTI) in first-line therapy at a time in which multiple options are available, and issues of antiviral efficacy, safety, simplicity and cost are critical to make informed decisions.

RECENT FINDINGS

DOR combination regimens have been tested in two large randomized double-blinded clinical trials in treatment-naïve patients, showing noninferiority to ritonavir-boosted darunavir-based and efavirenz (EFV)-based regimens. The main features of DOR are reviewed in this report including its antiviral activity, genetic barrier to resistance, safety, once-daily dosing and coformulation in a single tablet with tenofovir disoproxil fumarate and lamivudine. DOR pharmacokinetics and drug-drug interactions are also reviewed as DOR can be given without food restriction and has no interaction with proton pump inhibitors. DOR has shown a superior safety profile than EFV regarding neuropsychiatric and cutaneous adverse events. DOR is currently being investigated in treatment-experienced patients and in those with transmitted NNRTI drug resistance.

SUMMARY

DOR is a promising new NNRTI that could become the preferred drug in its class for treatment initiation. DOR has shown excellent antiviral activity in treatment-naïve patients, a better safety profile than EFV and a low potential for drug-drug interactions.

In Vitro Evaluation of the Drug Interaction Potential of Doravirine

Doravirine is a novel nonnucleoside reverse transcriptase inhibitor for the treatment of human immunodeficiency virus type 1 infection. In vitro studies were conducted to assess the potential for drug interactions with doravirine via major drug-metabolizing enzymes and transporters. Kinetic studies confirmed that cytochrome P450 3A (CYP3A) plays a major role in the metabolism of doravirine, with ∼20-fold-higher catalytic efficiency for CYP3A4 versus CYP3A5. Doravirine was not a substrate of breast cancer resistance protein (BCRP) and likely not a substrate of organic anion transporting polypeptide 1B1 (OATP1B1) or OATP1B3. Doravirine was not a reversible inhibitor of major CYP enzymes (CYP1A2, -2B6, -2C8, -2C9, -2C19, -2D6, and -3A4) or of UGT1A1, nor was it a time-dependent inhibitor of CYP3A4. No induction of CYP1A2 or -2B6 was observed in cultured human hepatocytes; small increases in CYP3A4 mRNA (≤20%) were reported at doravirine concentrations of ≥10 μM but with no corresponding increase in enzyme activity. In vitro transport studies indicated a low potential for interactions with substrates of BCRP, P-glycoprotein, OATP1B1 and OATP1B3, the bile salt extrusion pump (BSEP), organic anion transporter 1 (OAT1) and OAT3, organic cation transporter 2 (OCT2), and multidrug and toxin extrusion 1 (MATE1) and MATE2K proteins. In summary, these in vitro findings indicate that CYP3A4 and CYP3A5 mediate the metabolism of doravirine, although with different catalytic efficiencies. Clinical trials reported elsewhere confirm that doravirine is subject to drug-drug interactions (DDIs) via CYP3A inhibitors and inducers, but they support the notion that DDIs (either direction) are unlikely via other major drug-metabolizing enzymes and transporters.

Severe Renal Impairment Has Minimal Impact on Doravirine Pharmacokinetics

Doravirine is a novel nonnucleoside reverse transcriptase inhibitor in development for use with other antiretroviral therapies to treat human immunodeficiency virus type 1 (HIV-1) infection. Doravirine metabolism predominantly occurs via cytochrome P450 3A with <10% of elimination occurring via the renal pathway. As severe renal impairment can alter the pharmacokinetics (PK) of metabolically eliminated drugs, the effect of severe renal impairment on doravirine PK was assessed. A single dose of doravirine 100 mg was administered to subjects aged 18 to 75 years with an estimated glomerular filtration rate (eGFR) of <30 ml/min/1.73 m² (severe renal impairment group) and healthy controls with an eGFR of ≥80 ml/min/1.73 m², matched to the mean of the renal impairment group by age (±10 years) and weight (±10 kg). Doravirine plasma concentrations were determined at regular intervals, and safety was monitored throughout. The geometric mean ratios (90% confidence interval) for severe renal impairment/healthy subjects were 1.43 (1.00, 2.04), 1.38 (0.99, 1.92), and 0.83 (0.61, 1.15) for the plasma doravirine area under the curve from zero to infinity (AUC_0-∞), plasma concentration at 24 h postdose (C₂₄), and maximum plasma concentration (C_max), respectively. Doravirine was generally well tolerated in both groups. Based on the overall efficacy, safety, and PK profile of doravirine, the minor effect of severe renal impairment on doravirine PK observed in this study is not considered clinically meaningful. (This study has been registered at ClinicalTrials.gov under identifier NCT02641067.).

A Randomized Trial to Assess the Effect of Doravirine on the QTc Interval Using a Single Supratherapeutic Dose in Healthy Adult Volunteers

INTRODUCTION

Doravirine is a novel HIV-1 non-nucleoside reverse transcriptase inhibitor exhibiting a robust safety and efficacy profile in combination with other antiretrovirals. While existing data do not suggest that doravirine delays cardiac repolarization, the aim of this trial was to evaluate the effects of a supratherapeutic dose of doravirine on the heart-rate corrected QT (QTc) interval in healthy adults.

METHODS

A randomized, three-period, crossover, placebo-controlled trial was conducted in healthy adults, 18-55 years of age. Three treatments were administered: single-dose doravirine 1200 mg, placebo, and positive control (single-dose moxifloxacin 400 mg). QT interval measurements were collected at serial time points following treatment administration. Clinically significant placebo-corrected, baseline-adjusted QTc interval prolongation was defined when the upper bound of the two-sided 90% confidence interval (CI) for the mean effect on double delta QTc exceeded 10 ms. Doravirine tolerability and pharmacokinetics were also evaluated.

RESULTS

Forty-five subjects were enrolled and 39 completed the study per protocol. Fridericia's QT correction for heart rate was demonstrated to be inadequate; therefore, a population-specific correction was applied (QTcP). Assay sensitivity was confirmed with moxifloxacin. Following doravirine administration, QTc intervals did not exceed the pre-specified significance threshold - upper 90% CIs were ≤5.42 ms across all time points. Categorical analyses identified no outliers or clinically meaningful deviations. Doravirine geometric mean area under the time-concentration curve from dosing until 24 h post-dose (AUC_0-24) and maximum plasma concentration (C _max) were 119 µM·h and 9240 nM, respectively, which exceeded values expected following therapeutic dose administration of doravirine 100 mg, even in the setting of intrinsic and extrinsic factors that may cause increases in doravirine concentrations. All treatments were generally well tolerated.

CONCLUSION

A single oral supratherapeutic dose of doravirine 1200 mg does not cause clinically meaningful QTc interval prolongation in healthy adults.

Characterisation of the absorption, distribution, metabolism, excretion and mass balance of doravirine, a non-nucleoside reverse transcriptase inhibitor in humans

Absorption, distribution, metabolism and elimination of doravirine (MK-1439), a novel non-nucleoside reverse transcriptase inhibitor, were investigated. Two clinical trials were conducted in healthy subjects: an oral single dose [¹⁴C]doravirine (350 mg, ∼200 µCi) trial (n = 6) and an intravenous (IV) single-dose doravirine (100 µg) trial (n = 12). In vitro metabolism, protein binding, apparent permeability and P-glycoprotein (P-gp) transport studies were conducted to complement the clinical trials. Following oral [¹⁴C]doravirine administration, all of the administered dose was recovered. The absorbed dose was eliminated primarily via metabolism. An oxidative metabolite (M9) was the predominant metabolite in excreta and was the primary circulating metabolite (12.9% of circulating radioactivity). Following IV administration, doravirine clearance and volume of distribution were 3.73 L/h (95% confidence intervals (CI) 3.09, 4.49) and 60.5 L (95% CI 53.7, 68.4), respectively. In vitro, doravirine is not highly bound to plasma proteins (unbound fraction 0.24) and has good passive permeability. The metabolite M9 was generated by cytochrome P450 3A (CYP3A)4/5-mediated oxidation. Doravirine was a P-gp substrate but P-gp efflux is not expected to play a significant role in limiting doravirine absorption or to be involved in the elimination of doravirine. In conclusion, doravirine is a low clearance drug, primarily eliminated by CYP3A-mediated metabolism.