The effect of lersivirine, a next-generation NNRTI, on the pharmacokinetics of midazolam and oral contraceptives in healthy subjects

Drug-drug interactions that alter the exposure of glucuronidated drugs: Scope, UDP-glucuronosyltransferase (UGT) enzyme selectivity, mechanisms (inhibition and induction), and clinical significance

Drug-drug interactions (DDIs) arising from the perturbation of drug metabolising enzyme activities represent both a clinical problem and a potential economic loss for the pharmaceutical industry. DDIs involving glucuronidated drugs have historically attracted little attention and there is a perception that interactions are of minor clinical relevance. This review critically examines the scope and aetiology of DDIs that result in altered exposure of glucuronidated drugs. Interaction mechanisms, namely inhibition and induction of UDP-glucuronosyltransferase (UGT) enzymes and the potential interplay with drug transporters, are reviewed in detail, as is the clinical significance of known DDIs. Altered victim drug exposure arising from modulation of UGT enzyme activities is relatively common and, notably, the incidence and importance of UGT induction as a DDI mechanism is greater than generally believed. Numerous DDIs are clinically relevant, resulting in either loss of efficacy or an increased risk of adverse effects, necessitating dose individualisation. Several generalisations relating to the likelihood of DDIs can be drawn from the known substrate and inhibitor selectivities of UGT enzymes, highlighting the importance of comprehensive reaction phenotyping studies at an early stage of drug development. Further, rigorous assessment of the DDI liability of new chemical entities that undergo glucuronidation to a significant extent has been recommended recently by regulatory guidance. Although evidence-based approaches exist for the in vitro characterisation of UGT enzyme inhibition and induction, the availability of drugs considered appropriate for use as 'probe' substrates in clinical DDI studies is limited and this should be research priority.

Designing Out PXR Activity on Drug Discovery Projects: A Review of Structure-Based Methods, Empirical and Computational Approaches

This perspective discusses the role of pregnane xenobiotic receptor (PXR) in drug discovery and the impact of its activation on CYP3A4 induction. The use of structural biology to reduce PXR activity on drug discovery projects has become more common in recent years. Analysis of this work highlights several important molecular interactions, and the resultant structural modifications to reduce PXR activity are summarized. The computational approaches undertaken to support the design of new drugs devoid of PXR activation potential are also discussed. Finally, the SAR of empirical design strategies to reduce PXR activity is reviewed, and the key SAR transformations are discussed and summarized. In conclusion, this perspective demonstrates that PXR activity can be greatly diminished or negated on active drug discovery projects with the knowledge now available. This perspective should be useful to anyone who seeks to reduce PXR activity on a drug discovery project.

Multiple-Ascending Dose Study in Healthy Subjects to Assess the Pharmacokinetics, Tolerability, and CYP3A4 Interaction Potential of the T-Type Calcium Channel Blocker ACT-709478, A Potential New Antiepileptic Drug

BACKGROUND

ACT-709478 is a selective, orally available T-type calcium channel blocker being studied as a potential new treatment in epilepsy. ACT-709478 had previously been investigated in a single-ascending dose study up to a dose of 400 mg.

OBJECTIVES

The aim of this study was to investigate the safety, tolerability, pharmacokinetics, and pharmacodynamics of multiple doses of ACT-709478. In addition, the drug-drug interaction potential of multiple doses of ACT-709478 with the cytochrome P450 3A4 substrate midazolam was investigated.

METHODS

This double-blind, placebo-controlled, randomized study included 46 healthy male and female subjects. Ascending multiple oral doses of ACT-709478 were administered to 10 (cohorts 1-2) or 12 (cohorts 3-4) subjects (two taking placebo per cohort). In cohorts 1-2, 30 or 10 mg ACT-709478 was administered once daily for 12 days. An up-titration regimen was used in cohorts 3-4 with administration of 10, 30, and 60 mg for 7 days each in both cohorts and an additional dose level of 100 mg ACT-709478 once daily for 8 days in cohort 4. Single doses of midazolam were administered at baseline and concomitantly to 60 mg and 100 mg ACT-709478 in cohort 4. Blood sampling for pharmacokinetic evaluations and safety assessments (clinical laboratory, vital signs, adverse events, and electrocardiogram) were performed regularly. Holter electrocardiograms were recorded at baseline and for 24 h at steady state and central nervous system effects were assessed with pharmacodynamic tests at baseline and steady state.

RESULTS

ACT-709478 was absorbed with a time to reach the maximum plasma concentration of 3.5-4.0 h and eliminated with a half-life of 45-53 h. Steady state was reached after 5-7 days of dosing and exposure increased dose-proportionally. An accumulation index of approximately three fold was observed in cohorts 1 and 2. Exposure to midazolam was lower upon concomitant administration of 60 and 100 mg ACT-709478 compared to midazolam alone while the half-life and time to reach the maximum plasma concentration of midazolam remained unchanged, suggesting a weak induction at the gastrointestinal but not hepatic level. Pharmacokinetic parameters of 1-hydroxymidazolam were not affected by ACT-709478 administration. The most frequent adverse events were dizziness, somnolence, and headache. A tolerability signal was detected in cohort 1 (30 mg once daily); therefore, the dose was decreased to 10 mg once daily in cohort 2. The subsequently established up-titration regimen, starting with 10 mg once daily, considerably improved tolerability. Multiple doses up to 100 mg once daily were well tolerated. No treatment-related effects were detected on vital signs, clinical laboratory tests, Holter electrocardiogram variables, or in the pharmacodynamic tests.

CONCLUSIONS

ACT-709478 exhibits good tolerability up to 100 mg once daily using an up-titration regimen and pharmacokinetic properties that support further clinical investigations. A weak induction of gastrointestinal cytochrome P450 3A4 activity was observed, unlikely to be of clinical relevance. CLINICALTRIALS.

GOV IDENTIFIER

NCT03165097.

Examination of the Human Cytochrome P4503A4 Induction Potential of PF-06282999, an Irreversible Myeloperoxidase Inactivator: Integration of Preclinical, In Silico, and Biomarker Methodologies in the Prediction of the Clinical Outcome

The propensity for CYP3A4 induction by 2-(6-(5-chloro-2-methoxyphenyl)-4-oxo-2-thioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamide (PF-06282999), an irreversible inactivator of myeloperoxidase, was examined in the present study. Studies using human hepatocytes revealed moderate increases in CYP3A4 mRNA and midazolam-1'-hydroxylase activity in a PF-06282999 dose-dependent fashion. At the highest tested concentration of 300 μM, PF-06282999 caused maximal induction in CYP3A4 mRNA and enzyme activity ranging from 56% to 86% and 47% t0 72%, respectively, of rifampicin response across the three hepatocyte donor pools. In a clinical drug-drug interaction (DDI) study, the mean midazolam C_max and area under the curve (AUC) values following 14-day treatment with PF-06282999 decreased in a dose-dependent fashion with a maximum decrease in midazolam AUC_0-inf and C_max of ∼57.2% and 41.1% observed at the 500 mg twice daily dose. The moderate impact on midazolam pharmacokinetics at the 500 mg twice daily dose of PF-06282999 was also reflected in statistically significant changes in plasma 4β-hydroxycholesterol/cholesterol and urinary 6β-hydroxycortisol/cortisol ratios. Changes in plasma and urinary CYP3A4 biomarkers did not reach statistical significance at the 125 mg three times daily dose of PF-06282999, despite a modest decrease in midazolam systemic exposure. Predicted DDI magnitude based on the in vitro induction parameters and simulated pharmacokinetics of perpetrator (PF-06282999) and victim (midazolam) using the Simcyp (Simcyp Ltd., Sheffield, United Kingdom) population-based simulator were in reasonable agreement with the observed clinical data. Since the magnitude of the 4β-hydroxycholesterol or 6β-hydroxycortisol ratio change was generally smaller than the magnitude of the midazolam AUC change with PF-06282999, a pharmacokinetic interaction study with midazolam ultimately proved important for assessment of DDI via CYP3A4 induction.

Lersivirine - a new drug for HIV infection therapy

INTRODUCTION

Lersivirine (UK-453,061) is a novel second-generation non-nucleoside reverse transcriptase inhibitor (NNRTI). It binds reverse transcriptase in a distinct way leading to a unique resistance profile. The development of lersivirine was recently stopped in Phase IIb clinical development.

AREAS COVERED

This article describes the background of lersivirine, its pharmacodynamic and pharmacokinetic profile and its clinical efficacy in HIV-infected patients. Moreover, the authors review its resistance profile in addition to its possible interactions with coadministered drugs and safety and tolerability. The authors' evaluation is based on the articles retrieved from a Medline in addition to abstracts from major HIV conferences and workshops addressing lersivirine.

EXPERT OPINION

The authors believe that lersivirine has therapeutic potential for HIV-infected individuals with viral strains resistant against first-line NNRTIs. However, no large, well-powered studies have been conducted so far, which assess noninferiority against established antiretroviral agents. In February 2013, the developing company behind lersivirine halted further development as it was decided that it would not provide an improvement over existing therapies; perhaps this is an opportunity missed.

Effect of lersivirine co-administration on pharmacokinetics of methadone in healthy volunteers

BACKGROUND

Lersivirine is a next-generation non-nucleoside reverse transcriptase inhibitor under development for the treatment of HIV-1 infection. HIV-1-infected patients receiving methadone may have a limited choice of antiretroviral agents due to drug-drug interactions. As methadone is metabolized by CYP3A4 and lersivirine is a weak CYP3A4 inducer, it is possible that lersivirine may decrease methadone concentrations. This study evaluated the effect of lersivirine on the pharmacokinetics (PK) of R- and S-methadone enantiomers.

METHODS

An open-label, single-sequence study was performed in 13 HIV-negative volunteers receiving stable methadone maintenance therapy (MMT) (50-150 mg QD) for ≥3 months. Healthy volunteers received their methadone to steady-state on day 1 and lersivirine (1000 mg QD) plus their same methadone dose on Days 2-11. Assessments included PK, safety, short opiate withdrawal scale (SOWS), desires for drugs questionnaire (DDQ) and pupillary diameter measurements (PDMs).

RESULTS

Following administration of methadone alone or in combination with lersivirine, R- and S-methadone concentrations did not appear different (ratios of adjusted geometric means for PK parameters: 95-104%). Following co-administration of lersivirine and methadone, adverse events (AEs) were generally mild to moderate in severity. One patient discontinued due to nausea. An examination of objective (vital signs, AEs, PDM), subjective (SOWS and DDQ scores) and PK data suggested that subjects did not experience opioid withdrawal during the study.

CONCLUSIONS

Co-administration of lersivirine (1000 mg QD) with methadone did not result in clinically relevant changes in R-/S-methadone concentrations or opioid withdrawal symptoms. No methadone dose adjustment is required when lersivirine is administered alongside MMT.

Effect of rifampin and rifabutin on the pharmacokinetics of lersivirine and effect of lersivirine on the pharmacokinetics of rifabutin and 25-O-desacetyl-rifabutin in healthy subjects

Lersivirine is a nonnucleoside reverse transcriptase inhibitor (NNRTI) with a unique resistance profile exhibiting potent antiviral activity against wild-type HIV and several clinically relevant NNRTI-resistant strains. Lersivirine, a weak inducer of the cytochrome P450 (CYP) enzyme CYP3A4, is metabolized by CYP3A4 and UDP glucuronosyltransferase 2B7 (UGT2B7). Two open, randomized, two-way (study 1; study A5271008) or three-way (study 2; study A5271043) crossover phase I studies were carried out under steady-state conditions in healthy subjects. Study 1 (n = 17) investigated the effect of oral rifampin on the pharmacokinetics (PKs) of lersivirine. Study 2 (n = 18) investigated the effect of oral rifabutin on the PKs of lersivirine and the effect of lersivirine on the PKs of rifabutin and its active metabolite, 25-O-desacetyl-rifabutin. Coadministration with rifampin decreased the profile of the lersivirine area under the plasma concentration-time curve from time zero to 24 h postdose (AUC(24)), maximum plasma concentration (C(max)), and plasma concentration observed at 24 h postdose (C(24)) by 85% (90% confidence interval [CI], 83, 87), 83% (90% CI, 79, 85), and 92% (90% CI, 89, 94), respectively, versus the values for lersivirine alone. Coadministration with rifabutin decreased the lersivirine AUC(24), C(max), and C(24) by 34% (90% CI, 29, 39), 25% (90% CI, 16, 33), and 58% (90% CI, 52, 64), respectively, compared with the values for lersivirine alone. Neither the rifabutin concentration profile nor overall exposure was affected following coadministration with lersivirine. Lersivirine and rifabutin reduced the 25-O-desacetyl-rifabutin AUC(24) by 27% (90% CI, 21, 32) and C(max) by 27% (90% CI, 19, 34). Lersivirine should not be coadministered with rifampin, which is a potent inducer of CYP3A4, UGT2B7, and P-glycoprotein activity and thus substantially lowers lersivirine exposure. No dose adjustment of rifabutin is necessary in the presence of lersivirine; an upward dose adjustment of lersivirine may be warranted when it is coadministered with rifabutin.