Pharmacokinetics, safety and tolerability of long-acting parenteral intramuscular injection formulations of doravirine.

WHAT IS KNOWN AND OBJECTIVE: Doravirine is a non-nucleoside reverse transcriptase inhibitor indicated for the treatment of human immunodeficiency virus (HIV)-1 infection. This phase 1 study in healthy adults investigated the pharmacokinetics, safety and tolerability of long-acting parenteral (LAP) microsuspension formulations of doravirine administered as an intramuscular (IM) injection. METHODS: After confirmation of tolerability and safety of oral doravirine, 36 participants were randomized 1:1:1 to receive IM doravirine 200 mg as Treatment A (1 × 1 mL, 20% [200 mg/mL] suspension), B (1 × 0.66 mL, 30% [300 mg/mL] suspension) or C (2 × 0.5 mL, 20% suspension). Blood samples were taken as venous plasma, venous dried blood spots (DBS) and fingerstick DBS. RESULTS AND DISCUSSION: Plasma concentration-time profiles following IM treatments demonstrated rapid initial doravirine release, with initial peak ~4 days post-injection, followed by decline over the next ~6 days; a second peak was reached at ~24-36 days, corresponding to prolonged and sustained release, with measurable concentrations up to Day 183. Treatment C was associated with highest peak concentrations and shortest time to maximum concentration. Elimination half-lives for all IM formulations were prolonged versus oral administration (~46-58 days vs ~11-15 hours). Oral doravirine and IM doravirine were generally well tolerated; injection-site pain was the most common adverse event for IM doravirine. Doravirine concentrations from DBS samples showed strong correlations to venous plasma concentrations. WHAT IS NEW AND CONCLUSIONS: Novel doravirine LAP IM injection formulations investigated in this study demonstrated sustained plasma doravirine concentrations over a course of >20 weeks.

Leveraging model-informed approaches for drug discovery and development in the cardiovascular space.

Cardiovascular disease remains a significant global health burden, and development of cardiovascular drugs in the current regulatory environment often demands large and expensive cardiovascular outcome trials. Thus, the use of quantitative pharmacometric approaches which can help enable early Go/No Go decision making, ensure appropriate dose selection, and increase the likelihood of successful clinical trials, have become increasingly important to help reduce the risk of failed cardiovascular outcomes studies. In addition, cardiovascular safety is an important consideration for many drug development programs, whether or not the drug is designed to treat cardiovascular disease; modeling and simulation approaches also have utility in assessing risk in this area. Herein, examples of modeling and simulation applied at various stages of drug development, spanning from the discovery stage through late-stage clinical development, for cardiovascular programs are presented. Examples of how modeling approaches have been utilized in early development programs across various therapeutic areas to help inform strategies to mitigate the risk of cardiovascular-related adverse events, such as QTc prolongation and changes in blood pressure, are also presented. These examples demonstrate how more informed drug development decisions can be enabled by modeling and simulation approaches in the cardiovascular area.

Pharmacokinetics of vorapaxar and its metabolite following oral administration in healthy Chinese and American subjects.

AIM: Vorapaxar is a proteaseactivated receptor (PAR)-1 antagonist being developed for the prevention and treatment of thrombotic vascular events. To evaluate race/ethnic differences between Caucasians and Chinese in the pharmacokinetics of vorapaxar and its active metabolite SCH 2046273 (M20) or in the metabolite/parent ratio, we conducted a cross-study comparison on pharmacokinetic data of vorapaxar and M20 obtained from two similarly designed studies: one in healthy Chinese subjects and the other in a healthy Western (United States, [U.S.]) population. METHODS: The pharmacokinetic profiles of vorapaxar and M20 were characterized using open label, two treatment parallel group designs in men and women aged 18 - 45 years. Vorapaxar was administered orally as a single dose of 40 mg in Chinese subjects (n = 14) or 120 mg in U.S. subjects (n = 14), or 2.5 mg QD for 6 weeks in both studies (Chinese, n = 14; U.S., n = 23). RESULTS: Vorapaxar was rapidly absorbed in both Chinese and U.S. subjects. Vorapaxar and M20 had similar elimination half-lives. The range of metabolite/parent ratios after single dose or daily administration was largely overlapped in Chinese and U.S. subjects. Steady state was attained by day 21 for vorapaxar and M20 in both race/ethnic groups. The accumulation ratios for vorapaxar and M20 during daily administration were similar in Chinese and U.S. subjects. Vorapaxar was well-tolerated in Chinese and U.S. subjects. CONCLUSION: The pharmacokinetic profiles of vorapaxar and M20 and the metabolite/parent ratios in healthy Chinese were generally comparable to those in a healthy Western population.

Experiences of health tracking in mobile apps for multiple sclerosis: A qualitative content analysis of user reviews.

BACKGROUND: Mobile health applications (apps) are promising condition self-management tools for people living with multiple sclerosis (MS). However, most existing apps do not include health tracking features. This gap has been raised as a priority research topic, but the development of new self-management apps will require designers to understand the context and needs of those living with MS. Our aim was to conduct a content analysis of publicly available user reviews of existing MS self-management apps to understand desired features and guide the design of future apps. METHODS: We systematically reviewed MS self-management apps which were publicly available in English on the Google Play and iOS app stores. We then conducted sentiment and content analysis of recent user reviews which referenced health tracking and data visualization to understand self-reported experiences and feedback. RESULTS: Searches identified 75 unique apps, of which six met eligibility criteria and had reviews. One hundred and thirty-seven user reviews of these apps were eligible, though most were associated with a single app (n=108). Overall, ratings and sentiment scores skewed highly positive (Median [IQR]: Ratings - 5 [4-5], Sentiment scores - 0.70 [0.44-0.86]), though scores of individual apps varied. Content analysis revealed five themes: reasons for app usage, simple user experience, customization and flexibility, feature requests, and technical issues. Reviewers suggested that app customization, interconnectivity, and consolidated access to desired features should be considered in the design of future apps. User ratings weakly correlated with review sentiment scores (ρ = 0.27 [0.11-0.42]). CONCLUSIONS: Self-tracking options in MS apps are currently limited, though the apps that offer these functions are considered useful by individuals with MS. Additional qualitative research is required to understand how specific app features and opportunities for personalization should be incorporated into new self-management tools for this population.

Data Visualization for Chronic Neurological and Mental Health Condition Self-management: Systematic Review of User Perspectives.

BACKGROUND: Remote measurement technologies (RMT) such as mobile health devices and apps are increasingly used by those living with chronic neurological and mental health conditions. RMT enables real-world data collection and regular feedback, providing users with insights about their own conditions. Data visualizations are an integral part of RMT, although little is known about visualization design preferences from the perspectives of those living with chronic conditions. OBJECTIVE: The aim of this review was to explore the experiences and preferences of individuals with chronic neurological and mental health conditions on data visualizations derived from RMT to manage health. METHODS: In this systematic review, we searched peer-reviewed literature and conference proceedings (PubMed, IEEE Xplore, EMBASE, Web of Science, Association for Computing Machinery Computer-Human Interface proceedings, and the Cochrane Library) for original papers published between January 2007 and September 2021 that reported perspectives on data visualization of people living with chronic neurological and mental health conditions. Two reviewers independently screened each abstract and full-text article, with disagreements resolved through discussion. Studies were critically appraised, and extracted data underwent thematic synthesis. RESULTS: We identified 35 eligible publications from 31 studies representing 12 conditions. Coded data coalesced into 3 themes: desire for data visualization, impact of visualizations on condition management, and visualization design considerations. Data visualizations were viewed as an integral part of users' experiences with RMT, impacting satisfaction and engagement. However, user preferences were diverse and often conflicting both between and within conditions. CONCLUSIONS: When used effectively, data visualizations are valuable, engaging components of RMT. They can provide structure and insight, allowing individuals to manage their own health more effectively. However, visualizations are not "one-size-fits-all," and it is important to engage with potential users during visualization design to understand when, how, and with whom the visualizations will be used to manage health.

Facial and Vocal Markers of Schizophrenia Measured Using Remote Smartphone Assessments: Observational Study.

BACKGROUND: Machine learning-based facial and vocal measurements have demonstrated relationships with schizophrenia diagnosis and severity. Demonstrating utility and validity of remote and automated assessments conducted outside of controlled experimental or clinical settings can facilitate scaling such measurement tools to aid in risk assessment and tracking of treatment response in populations that are difficult to engage. OBJECTIVE: This study aimed to determine the accuracy of machine learning-based facial and vocal measurements acquired through automated assessments conducted remotely through smartphones. METHODS: Measurements of facial and vocal characteristics including facial expressivity, vocal acoustics, and speech prevalence were assessed in 20 patients with schizophrenia over the course of 2 weeks in response to two classes of prompts previously utilized in experimental laboratory assessments: evoked prompts, where subjects are guided to produce specific facial expressions and speech; and spontaneous prompts, where subjects are presented stimuli in the form of emotionally evocative imagery and asked to freely respond. Facial and vocal measurements were assessed in relation to schizophrenia symptom severity using the Positive and Negative Syndrome Scale. RESULTS: Vocal markers including speech prevalence, vocal jitter, fundamental frequency, and vocal intensity demonstrated specificity as markers of negative symptom severity, while measurement of facial expressivity demonstrated itself as a robust marker of overall schizophrenia symptom severity. CONCLUSIONS: Established facial and vocal measurements, collected remotely in schizophrenia patients via smartphones in response to automated task prompts, demonstrated accuracy as markers of schizophrenia symptom severity. Clinical implications are discussed.

A Model-Based Approach to Bridging Plasma and Dried Blood Spot Concentration Data for Phase 3 Verubecestat Trials.

In-clinic venous dried blood spot (DBS) pharmacokinetic (PK) sampling was incorporated into two phase 3 studies of verubecestat for Alzheimer's disease (EPOCH [NCT01739348] and APECS [NCT01953601]), as a potential alternative to plasma PK sampling. Initially, plasma and DBS PK samples were collected concurrently to better understand the DBS-plasma verubecestat concentration relationship, with the intention of discontinuing DBS or plasma sampling following interim analysis. Following initial analyses and comparison of results with prespecified selection criteria, plasma PK sampling was discontinued; however, a stability issue resulting in generally lower DBS verubecestat concentrations with longer collection-to-assay times was subsequently discovered (associated with non-compliance in DBS sample handling), prompting reintroduction of plasma sampling. To enable inclusion of DBS data in population PK analyses, a conversion algorithm for calculating plasma-equivalent concentrations (accounting for DBS sample instability) was developed using paired (time-matched) plasma and DBS data from the EPOCH study. Verubecestat population PK models developed from pooled phase 1/1b and EPOCH data using either (1) plasma-only data or (2) plasma and plasma-equivalent concentrations (calculated from non-paired DBS samples) yielded similar results. The algorithm robustness was demonstrated using DBS data from paired samples from the APECS study and comparison between plasma and plasma-equivalent concentrations. The population PK model was updated with APECS data (both plasma and, if no plasma sample available, plasma equivalents). The results demonstrated similar PK in the two phase 3 populations and exposures consistent with expectations from phase 1 data. This case study illustrates challenges with employing new sampling techniques in large, global trials and describes lessons learned.

An Investigation of Instability in Dried Blood Spot Samples for Pharmacokinetic Sampling in Phase 3 Trials of Verubecestat.

In-clinic dried blood spot (DBS) pharmacokinetic (PK) sampling was incorporated into two phase 3 studies of verubecestat for Alzheimer's disease (EPOCH [NCT01739348] and APECS [NCT01953601]), as a potential alternative to plasma PK sampling for improved logistical feasibility and decreased blood volume burden. However, an interim PK analysis revealed verubecestat concentrations in DBS samples declined with time to assay in both trials. An investigation revealed wide variation in implementation practices for DBS sample handling procedures resulting in insufficient desiccation which caused verubecestat instability. High-resolution mass spectrometry evaluations of stressed and aged verubecestat DBS samples revealed the presence of two hydrolysis degradants. To minimize instability, new DBS handling procedures were implemented that provided additional desiccant and minimized the time to analysis. Both verubecestat hydrolysis products were previously discovered and synthesized during active pharmaceutical ingredient stability characterization. A liquid chromatography-mass spectrometry assay to quantitate the dominant verubecestat degradant in DBS samples was developed and validated. The application of this method to stressed and aged verubecestat DBS samples confirmed that degradant concentrations accounted for the observed decreases in the verubecestat concentration. Furthermore, after increasing desiccant amounts, degradant concentrations accounted for approximately 7% of the verubecestat concentration in DBS clinical samples, indicating that issues with sample handling were minimized with new storage and shipping conditions. This case study illustrates the challenges with employing new sampling techniques in large, global trials, and the importance of anticipating and mitigating implementation risks.

Digitally Enabled, Patient-Centric Clinical Trials: Shifting the Drug Development Paradigm.

The rapidly advancing field of digital health technologies provides a great opportunity to radically transform the way clinical trials are conducted and to shift the clinical trial paradigm from a site-centric to a patient-centric model. Merck's (Kenilworth, NJ) digitally enabled clinical trial initiative is focused on introduction of digital technologies into the clinical trial paradigm to reduce patient burden, improve drug adherence, provide a means of more closely engaging with the patient, and enable higher quality, faster, and more frequent data collection. This paper will describe the following four key areas of focus from Merck's digitally enabled clinical trials initiative, along with corresponding enabling technologies: (i) use of technologies that can monitor and improve drug adherence (smart dosing), (ii) collection of pharmacokinetic (PK), pharmacodynamic (PD), and biomarker samples in an outpatient setting (patient-centric sampling), (iii) use of digital devices to collect and measure physiological and behavioral data (digital biomarkers), and (iv) use of data platforms that integrate digital data streams, visualize data in real-time, and provide a means of greater patient engagement during the trial (digital platform). Furthermore, this paper will discuss the synergistic power in implementation of these approaches jointly within a trial to enable better understanding of adherence, safety, efficacy, PK, PD, and corresponding exposure-response relationships of investigational therapies as well as reduced patient burden for clinical trial participation. Obstacle and challenges to adoption and full realization of the vision of patient-centric, digitally enabled trials will also be discussed.

Atogepant Is Not Associated With Clinically Meaningful Alanine Aminotransferase Elevations in Healthy Adults.

Atogepant is a potent, selective, oral calcitonin gene-related peptide (CGRP) receptor antagonist in development for migraine prevention. The chemical structure of atogepant is distinct from previous CGRP receptor antagonists, which were associated with elevated serum alanine aminotransferase (ALT) in clinical trials. Here, we report the safety, tolerability, and pharmacokinetics (PKs) of a once-daily supratherapeutic dose (170 mg) of atogepant for 28 days from a randomized, double-blind, placebo-controlled phase I trial in healthy participants. Overall safety, hepatic safety, and plasma PK parameters were evaluated. Thirty-four participants aged 23-55 years enrolled; 28 (82.4%) completed the study in accordance with the protocol. Multiple doses of 170 mg atogepant for 28 consecutive days were generally well-tolerated. All adverse events (AEs; reported in 87.0% of the atogepant group; 72.7%, placebo) were mild in severity except one serious AE of subarachnoid hemorrhage due to a bicycle accident and not considered related to treatment. There were two discontinuations due to AEs, both with atogepant, one considered possibly related to treatment. Over 28 days of treatment, no participant receiving atogepant had an ALT elevation above 1.5 × upper limit of normal. Change from baseline in serum ALT levels was not different between atogepant and placebo. Atogepant is rapidly absorbed (median time to maximum plasma concentration, ~ 2 hours) with an apparent terminal half-life of ~ 11 hours, and no evidence of accumulation after once-daily dosing. Overall, atogepant at a high oral dose is safe and well-tolerated in healthy participants with no clinically meaningful elevations in ALT.

Atogepant Has No Clinically Relevant Effects on the Pharmacokinetics of an Ethinyl Estradiol/Levonorgestrel Oral Contraceptive in Healthy Female Participants.

The incidence of migraine is higher among women than men and peaks during the reproductive years, when contraceptive medication use is common. Atogepant, a potent, selective antagonist of the calcitonin gene-related peptide receptor-in development for migraine prevention-is thus likely to be used by women taking oral contraceptives. This phase 1, open-label, single-center, 2-period, fixed-sequence study examined the effect of multiple-dose atogepant 60 mg once daily on the single-dose pharmacokinetics of a combination oral contraceptive, ethinyl estradiol 0.03 mg and levonorgestrel 0.15 mg (EE/LNG), in healthy postmenopausal or oophorectomized women. For participants in period 1, a single dose of EE/LNG was followed by a 7-day washout. In period 2, atogepant was given once daily on days 1-17; an oral dose of EE/LNG was coadministered with atogepant on day 14. Plasma pharmacokinetic parameters for EE and LNG were assessed following administration with and without atogepant. Twenty-six participants aged 45-64 years enrolled; 22 completed the study in accordance with the protocol. The area under the concentration-time curve extrapolated to infinity (AUC0-∞ ) of LNG was increased by 19% when administered with atogepant. Coadministration of atogepant and a single dose of EE/LNG did not substantially alter the pharmacokinetics of EE; the ∼19% increase in plasma AUC0-∞ of LNG is not anticipated to be clinically significant. Overall, atogepant alone and in combination with EE/LNG was generally well tolerated, with no new safety signals identified.

Ubrogepant Is Not Associated With Clinically Meaningful Elevations of Alanine Aminotransferase in Healthy Adult Males.

Ubrogepant is a novel, oral calcitonin gene-related peptide (CGRP) receptor antagonist intended for the acute treatment of migraine attacks. Ubrogepant has a chemical structure distinct from previous small-molecule CGRP receptor antagonists that were associated with elevated serum alanine aminotransferase (ALT) in clinical trials. Here, we report overall and hepatic safety data from two placebo-controlled phase I trials of ubrogepant, spray-dried oral compressed tablet (SD-OCT) in healthy male volunteers. Trial A was a pharmacokinetic (PK) trial of single (100-400 mg) and multiple (40-400 mg) ascending doses. Trial B was a dedicated hepatic safety trial assessing daily use of ubrogepant 150 mg for 28 days. Serum ALT (as hepatotoxicity biomarker) and PK data are reported. Ubrogepant was well-tolerated in both trials, with a low incidence of adverse events that did not differ greatly from placebo. Changes in mean ALT levels were minimal and similar to placebo. Over 28 days of treatment, the mean percentage change in ALT from baseline was < 5% at all time points. No participant in either trial demonstrated ALT ≥ 3× upper limit of normal at any time. Ubrogepant SD-OCT demonstrated linear PK appropriate for acute treatment of migraine, with rapid uptake (time of maximum plasma concentration (tmax ): 2-3 hours) and no accumulation with daily use. Overall, there was no evidence of ubrogepant-associated hepatotoxicity with daily doses up to 400 mg for 10 days or with daily ubrogepant 150 mg for 28 days. Supratherapeutic dosing is a useful strategy for characterizing hepatic safety in early drug development.

Safety, Tolerability, and Pharmacokinetics of the ß-Site Amyloid Precursor Protein-Cleaving Enzyme 1 Inhibitor Verubecestat (MK-8931) in Healthy Elderly Male and Female Subjects.

ß-site amyloid precursor protein-cleaving enzyme 1 (BACE1) is required for the production of ß-amyloid peptides, which are implicated in the etiology of Alzheimer's disease. The safety and pharmacokinetics of the BACE1 inhibitor verubecestat have previously been studied in young adults aged 19-45 years. In this randomized, placebo-controlled, phase I study (protocol MK-8931-006), we investigated the safety, tolerability, and pharmacokinetics of a single dose (100 mg) or multiple doses (30, 80, and 120 mg) once daily for 28 days of verubecestat in healthy elderly subjects. Safety end points were assessed at baseline and during the duration of the study period and indicated that verubecestat was generally well tolerated. Verubecestat pharmacokinetics were similar between healthy elderly male and female subjects and similar to those reported in healthy young males in previous studies. These data supported subsequent studies to assess the potential efficacy of verubecestat in subjects with Alzheimer's disease.

Pharmacokinetics and Pharmacodynamics of the BACE1 Inhibitor Verubecestat (MK-8931) in Healthy Japanese Adults: A Randomized, Placebo-Controlled Study.

ß-site amyloid precursor protein cleaving enzyme 1 (BACE1) is required for the production of ß-amyloid (Aß) peptides and is considered a potential treatment target for Alzheimer's disease (AD). To support Japan's participation in the global clinical development program, we characterized the safety, pharmacokinetics (PKs), and pharmacodynamics of the BACE1 inhibitor verubecestat (MK-8931) in 24 healthy Japanese adults in a two-part, single-center, randomized, placebo-controlled phase I trial (protocol MK-8931-007) and compared the results with historical data from non-Japanese subjects. Both single (20, 100, and 450 mg) and multiple (80 and 150 mg once daily for 14 days) doses of verubecestat were well tolerated. Verubecestat's PK profile was similar in Japanese and non-Japanese subjects. Verubecestat also reduced mean cerebrospinal fluid concentrations of the Aß proteins Aß40, Aß42, and soluble ß fragment of amyloid precursor protein; the level of reduction was comparable between Japanese and non-Japanese subjects. These results support the continued global development of verubecestat as a potential disease-modifying agent for Japanese and non-Japanese subjects who are at risk for developing AD.

Leveraging Digital Health Technologies and Outpatient Sampling in Clinical Drug Development: A Phase I Exploratory Study.

Merck & Co, Inc (Kenilworth, NJ) is investing in approaches to enrich clinical trial data and augment decision making through use of digital health technologies, outpatient sampling, and real-time data access. As part of this strategy, a phase I study was conducted to explore a few technologies of interest. In this fixed-sequence two-period trial, 16 healthy subjects were administered 50-mg once-daily sitagliptin packaged in a bottle that electronically captured the date and time study medication was dispensed (period 1) and in a traditional pharmacy bottle (period 2). Dried blood spot samples were collected for sitagliptin concentration analysis on select study days, both in clinic and at home, with collection time recorded using an electronic diary in period 1 and by clinic staff in period 2. Study results demonstrated the feasibility and subject acceptance of collecting digital adherence data and outpatient dried blood spot samples in clinical trials and highlighted areas for future improvements.

The BACE1 inhibitor verubecestat (MK-8931) reduces CNS ß-amyloid in animal models and in Alzheimer's disease patients.

ß-Amyloid (Aß) peptides are thought to be critically involved in the etiology of Alzheimer's disease (AD). The aspartyl protease ß-site amyloid precursor protein cleaving enzyme 1 (BACE1) is required for the production of Aß, and BACE1 inhibition is thus an attractive target for the treatment of AD. We show that verubecestat (MK-8931) is a potent, selective, structurally unique BACE1 inhibitor that reduced plasma, cerebrospinal fluid (CSF), and brain concentrations of Aß40, Aß42, and sAPPß (a direct product of BACE1 enzymatic activity) after acute and chronic administration to rats and monkeys. Chronic treatment of rats and monkeys with verubecestat achieved exposures >40-fold higher than those being tested in clinical trials in AD patients yet did not elicit many of the adverse effects previously attributed to BACE inhibition, such as reduced nerve myelination, neurodegeneration, altered glucose homeostasis, or hepatotoxicity. Fur hypopigmentation was observed in rabbits and mice but not in monkeys. Single and multiple doses were generally well tolerated and produced reductions in Aß40, Aß42, and sAPPß in the CSF of both healthy human subjects and AD patients. The human data were fit to an amyloid pathway model that provided insight into the Aß pools affected by BACE1 inhibition and guided the choice of doses for subsequent clinical trials.

Safety, tolerability and pharmacokinetics of doravirine, a novel HIV non-nucleoside reverse transcriptase inhibitor, after single and multiple doses in healthy subjects.

BACKGROUND: Doravirine is a novel non-nucleoside inhibitor of HIV-1 reverse transcriptase with potent activity against wild-type virus (95% inhibitory concentration 19 nM, 50% human serum). Doravirine has low potential to cause drug-drug interactions since it is primarily eliminated by oxidative metabolism and does not inhibit or significantly induce drug-metabolizing enzymes. METHODS: The pharmacokinetics and safety of doravirine were investigated in two double-blind, dose-escalation studies in healthy males. Thirty-two subjects received single doses of doravirine (6-1,200 mg) or matching placebo tablets; 40 subjects received doravirine (30-750 mg) or matching placebo tablets once daily for 10 days. In addition, the effect of doravirine (120 mg for 14 days) on single-dose pharmacokinetics of the CYP3A substrate midazolam was evaluated (10 subjects). RESULTS: The maximum plasma concentration (Cmax) of doravirine was achieved within 1-5 h with an apparent terminal half-life of 12-21 h. Consistent with single-dose pharmacokinetics, steady state was achieved after approximately 7 days of once daily administration, with accumulation ratios (day 10/day 1) of 1.1-1.5 in the area under the plasma concentration-time curve during the dosing interval (AUC0-24 h), Cmax and trough plasma concentration (C24 h). All dose levels produced C24 h>19 nM. Administration of 50 mg doravirine with a high-fat meal was associated with slight elevations in AUC time zero to infinity (AUC0-∞) and C24 h with no change in Cmax. Midazolam AUC0-∞ was slightly reduced by coadministration of doravirine (geometric mean ratio 0.82, 90% CI 0.70, 0.97). There was no apparent relationship between adverse event frequency or intensity and doravirine dose. No rash or significant central nervous system events other than headache were reported. CONCLUSIONS: Doravirine is generally well tolerated in single doses up to 1,200 mg and multiple doses up to 750 mg once daily for up to 10 days, with a pharmacokinetic profile supportive of once-daily dosing. Doravirine at steady state slightly reduced the exposure of coadministered midazolam, to a clinically unimportant extent.

Model-based development of anacetrapib, a novel cholesteryl ester transfer protein inhibitor.

A model-based strategy was used to inform the early clinical development of anacetrapib, a novel cholesteryl ester transfer protein inhibitor under development for the treatment of hyperlipidemia. The objectives of this model-based approach were to enable bridging variable pharmacokinetic effects, differences among formulations used in development, and to identify an appropriate dose for the phase III confirmatory program. Nonlinear mixed effects PK/PD models were initially developed based on data obtained from multiple phase I studies and later were updated with data from a phase IIb study. The population pharmacokinetic model described differences between the liquid-filled capsule used in phase I and phase IIb and the hot-melt extruded (HME) tablet formulation introduced in phase III, allowing for bridging of the two formulations, and quantified the complex relationship of apparent anacetrapib bioavailability with subject meal intake. Proportional E(max) models quantified the relationships between anacetrapib trough concentration and lipoprotein effects (LDL-C and HDL-C), with covariate effects of study population (normal volunteers vs. patients), and co-administration with HMG-CoA reductase inhibitor ("statin"). The interaction between anacetrapib and atorvastatin suggested pharmacological independence, i.e., that when given together, each agent exerts the same proportional lipid effect observed from monotherapy. Clinical trial simulation was used to examine the robustness of the effects to random dietary indiscretion, and found that the results were robust as long as patients generally adhered to a low-fat diet. These results allowed the selection of the 100 mg dose with the HME formulation for phase III development even though this dose and formulation were not specifically studied in a phase IIb trial.