Search

The capsid assembly modulator JNJ-56136379 (bersacapavir) disrupts hepatitis B virus replication. It is metabolized via cytochrome P450 (CYP) 3A, but little is known about the drug-drug interactions of JNJ-56136379 when combined with drugs that inhibit or are metabolized by CYP3A. In a phase 1, open-label trial (NCT03945539), healthy adults received 1 dose of JNJ-56136379 with and without 21 days of prior exposure to itraconazole 200 mg (CYP3A inhibitor). In a second phase 1, open-label trial (NCT03111511), healthy women received 1 dose of drospirenone/ethinyl estradiol and midazolam before and after 15 days of JNJ-56136379. Itraconazole increased the area under the plasma concentration-time curve (AUC) of JNJ-56136379 by 38%. JNJ-56136379 reduced the maximum observed concentration and AUC of midazolam (CYP3A substrate) by 42%-54%, increased AUC of ethinyl estradiol by 1.6-fold, but had no effect on drospirenone pharmacokinetics. Overall, these results demonstrated that a strong CYP3A inhibitor (itraconazole) modestly increased JNJ-56136379 exposure. Furthermore, JNJ-56136379 was a weak inducer of CYP3A (midazolam) and increased ethinyl estradiol exposure; coadministration of high-dose estrogen-based contraceptives and JNJ-56136379 is not recommended.

Background Pharmacokinetics and safety of JNJ-64530440, a hepatitis B virus capsid assembly modulator producing normal empty capsids (CAM-N), in healthy volunteers were evaluated. Methods This Phase I study (NCT03439488) was a double-blind, randomised, placebo-controlled study. Adults ( n = 10/cohort, five Asian/five non-Asian), randomised 4:1, received single-ascending doses of oral JNJ-64530440 (first- and second-generation formulations) or placebo under fasted (50, 150, 300 and 900 mg) or fed (300, 750, 1,000, 2000 and 4000 mg) conditions. Multiple-ascending doses of 750 or 2000 mg once daily and 750 mg twice daily JNJ-64530440 (second-generation formulation) for 7 days were evaluated. Pharmacokinetic parameters were estimated from plasma concentrations. Safety was assessed throughout. Results Less than dose-proportional increases in maximum plasma concentrations (Cmax) and area under the plasma concentration–time curves (AUCs) were observed across the doses. Mean plasma half-lives ranged from 9.3 to 14.5 h. Cmax and AUC were ∼two fold higher under fed versus fasting conditions and slightly higher in Asians versus Caucasians. JNJ-64530440 doses ≥750 mg achieved plasma levels higher than protein-binding adjusted concentrations demonstrating in vitro antiviral activity. No serious adverse events (AEs), treatment discontinuations or dose-limiting toxicities were seen. AE frequency/severity did not increase with dose. Conclusions Single (up to 4000 mg) and multiple doses (up to 2000 mg for 7 days) of JNJ-64530440 were well tolerated in healthy volunteers. Multiple doses ≥750 mg/day achieved plasma concentrations expected to have antiviral activity that may lower hepatitis B surface antigen. No clinically relevant differences in tolerability or pharmacokinetic parameters were seen between Asians versus Caucasians.

Background JNJ-73763989 comprises two hepatitis B virus (HBV)-specific, liver-targeted N-galactosamine-conjugated short interfering RNA triggers, JNJ-73763976 and JNJ-73763924. JNJ-73763989 pharmacokinetics, safety and tolerability were assessed in two phase 1 studies: Japanese (NCT04002752), and non-Japanese healthy participants and chronic hepatitis B (CHB) patients also receiving the HBV capsid assembly modulator JNJ-56136379 and a nucleos(t)ide analogue (NA) (NCT03365947). Methods Healthy participant cohorts were double-blind and randomized to receive a single subcutaneous JNJ-73763989 dose (non-Japanese participants, 35, 100, 200, 300 or 400 mg; Japanese participants, 25, 100 or 200 mg) or placebo. JNJ-73763976 and JNJ-73763924 plasma concentrations were assessed over 48 h. CHB patients received JNJ-73763989 200 mg every 4 weeks plus daily oral JNJ-56136379 250 mg and NA in an open-label fashion. Safety and tolerability were assessed through Day 28 (healthy participants) or Day 112 (patients). Results Thirty non-Japanese ( n = 4/dose; placebo, n = 10) and 24 Japanese healthy participants ( n = 6/dose; placebo, n = 6) were randomized. JNJ-73763976 and JNJ-73763924 exposure generally increased in a dose-proportional manner. Mean plasma half-life was 4–9 h. No differences between pharmacokinetic parameters were apparent between non-Japanese and Japanese healthy participants. In the 12 CHB patients, mean JNJ-73763976, JNJ-73763924 and JNJ-56136379 plasma concentrations 2 h post-dose on Day 29 were 663, 269 and 14,718 ng/mL, respectively. In both studies, all adverse events were mild/moderate. Conclusion JNJ-73763976 and JNJ-73763924 had short plasma half-lives and exposure generally increased in a dose-proportional manner; there were no pharmacokinetic differences between Japanese and non-Japanese healthy adults. JNJ-73763989 with or without JNJ-56136379 and NA was generally safe and well tolerated.

Objectives We investigated JNJ-64530440 (a hepatitis B virus capsid assembly modulator) safety, antiviral activity and pharmacokinetics in patients with chronic hepatitis B (CHB) (Phase 1b, NCT03439488). Methods Twenty treatment-naive, HBeAg-positive or -negative CHB patients were randomized 4‍:‍1 to JNJ-64530440 750 mg once or twice daily, or placebo for 28 days. Results All patients (mean age 43.8 years; 85% male; 70% White; 20% HBeAg positive) completed dosing/28 day follow-up. Mild-to-moderate treatment-emergent adverse events occurred in 3/4 (placebo), 6/8 (once-daily) and 4/8 (twice-daily) patients; mostly fatigue, increased alanine aminotransferase, decreased neutrophil count, and headache. Hepatitis B virus (HBV) DNA was substantially reduced; mean (range) changes from baseline at day 29 were: −3.2 (−2.4 to −3.9) (once-daily) and −3.3 (−2.6 to −4.1) (twice-daily) log10 IU/mL; placebo 0.1 (0.7 to −0.6) log10 IU/mL. HBV DNA levels were below the lower limit of quantification (LLOQ) in 5/8 (once-daily) and 3/8 (twice-daily) patients. For patients with detectable baseline HBV RNA, mean (SE) changes versus baseline in HBV RNA at day 29 were: −2.65 (0.81) (once-daily) and −2.94 (0.33) (twice-daily) log10 copies/mL. HBV RNA levels were ‘target not detected’ in 4/6 (once-daily) and 3/7 (twice-daily) patients. JNJ-64530440 pharmacokinetics in CHB patients were comparable with those in healthy volunteers. Conclusions JNJ-64530440 750 mg once-daily or twice-daily for 28 days was well tolerated and achieved potent antiviral activity in CHB patients.

This open-label, phase IIa study assessed the safety, pharmacokinetics, and efficacy of direct-acting antiviral agent (DAA) regimens in patients with chronic hepatitis C virus (HCV) infection. Multiple 6-12-week oral regimens of 400-800 mg once daily (QD) AL-335 + 50 mg QD/every other day odalasvir ± 75-150 mg QD simeprevir were evaluated in treatment-naïve, HCV genotype (GT)1/3-infected patients without cirrhosis. Safety/pharmacokinetic parameters, HCV-RNA, and sequencing data were assessed. Treatment regimens for later study cohorts were adjusted based on emerging data. In total, 112 patients were enrolled. Three serious treatment-emergent adverse events occurred, one of which (a Mobitz type 1 second-degree atrioventricular block [Wenckebach]) was possibly related to high odalasvir exposure and resulted in premature discontinuation of study drugs. No other clinically significant safety findings were identified. GT1-infected patients receiving 3-DAA for 6-8 weeks achieved 100% sustained virologic response 12 weeks and 24 weeks after the end of treatment (sustained virologic response [SVR12/24]). GT1-infected patients receiving 2-DAA or GT3-infected patients receiving 3-DAA had SVR12/24 less than 90%, whether treated for 8 weeks or 12 weeks. Virologic failure was associated with the emergence of generally persistent NS5A and/or transient NS5B resistance-associated substitutions in most patients. Pharmacokinetic characteristics of the three drugs were also elucidated. Conclusions: In treatment-naïve subjects without cirrhosis, AL-335 + odalasvir + simeprevir for 6-8 weeks was generally safe and highly efficacious against HCV GT1. However, inadequate efficacy was observed for the 2-DAA regimen in GT1-infected subjects and the 3-DAA regimen in GT3-infected subjects.

AIMS: The aim of this study was to evaluate the drug–drug interaction between pimodivir, a novel, non‐nucleoside polymerase basic protein 2 (PB2) subunit inhibitor of the influenza A virus polymerase complex, and oseltamivir, to assess the feasibility of this combination therapy. Furthermore, single‐ and multiple‐dose pharmacokinetics and safety of pimodivir in healthy volunteers were assessed. METHODS: In Part 1 of this open‐label Phase 1 study, healthy volunteers (n = 18) were randomized to one of six cross‐over treatment sequences, each comprising administration of oseltamivir 75 mg or pimodivir 600 mg or combination thereof twice daily on Days 1–4, followed by a single morning dose on Day 5. Between each treatment session, there was a minimum 5‐day washout period. In Part 2, healthy volunteers (n = 16) randomly received pimodivir 600 mg or placebo (3:1) twice daily on Days 1–9, followed by a single morning dose on Day 10. Pharmacokinetics of pimodivir, oseltamivir and oseltamivir carboxylate, and safety were assessed. RESULTS: In Part 1, co‐administration of pimodivir with oseltamivir increased the C (max) of pimodivir by 31% (90% CI: 0.92–1.85) with no change in C (min) or AUC(12h). Pimodivir had no effect on oseltamivir or oseltamivir carboxylate pharmacokinetics. In Part 2, after single‐ and multiple‐dose administration of pimodivir, there was a 1.2‐ and 1.8‐fold increase in C (max) and AUC(12h), respectively, between Day 1 and Day 10. The most frequently reported treatment‐emergent adverse event was diarrhoea (n = 7 each in Part 1 and 2). CONCLUSION: Combination treatment with pimodivir and oseltamivir in healthy volunteers showed no clinically relevant drug–drug interactions. No safety concerns were identified with pimodivir 600 mg twice daily alone or in combination with oseltamivir 75 mg twice daily.

The phase 2, open-label ACCORDION (ClinicalTrials.gov: NCT02349048) study investigated the efficacy, safety and pharmacokinetics of a 6- or 8-week regimen of simeprevir, daclatasvir and sofosbuvir in treatment-naïve patients with chronic hepatitis C virus (HCV) genotype (GT) 1 infection and either early-stage fibrosis or compensated cirrhosis. Patients were assigned to treatment groups according to their fibrosis stage. Early-stage fibrosis: simeprevir 150 mg, daclatasvir 60 mg, sofosbuvir 400 mg once daily for 6 weeks; compensated cirrhosis: same regimen for 8 weeks. The primary endpoint was sustained virologic response 12 weeks after the end of treatment (SVR12). Safety, tolerability and pharmacokinetics of simeprevir, daclatasvir and sofosbuvir were investigated. Sixty-eight patients were treated (6-week group: n = 59; 8-week group: n = 9). SVR12 was achieved by 86.4% (51/59) of patients with early-stage fibrosis and by 100% (9/9) of patients with cirrhosis. The main reason for not achieving SVR12 in the 6-week group was viral relapse (11.9%; 7/59). One patient had on-treatment failure due to an early withdrawal (lost to follow-up due to incarceration). One patient with SVR12 in the 6-week group had a late viral relapse at post-treatment week 24. No clinically significant drug-drug interactions were observed. Adverse events were reported in 63.2% of patients (43/68) and were mainly grade 1/2. None of these led to treatment discontinuation. The 3 direct-acting antiviral regimens of simeprevir, daclatasvir and sofosbuvir were safe and well tolerated in treatment-naïve, HCV GT1-infected patients with early-stage fibrosis or compensated cirrhosis.

Background This double-blind, first-in-human Phase I study evaluated pharmacokinetics, safety and tolerability of AL-794 (prodrug of ALS-033719), a potent endonucle-ase inhibitor of influenza A and B in healthy volunteers. Methods Healthy adult volunteers were randomized to AL-794 (50–2,000 mg single ascending doses, fasting) or placebo (5 cohorts, n=6:2 AL-794: placebo/cohort) in part 1, and AL-794 (50–600 mg multiple ascending doses, twice-daily, fed or fasted) or placebo (3 cohorts, n=8:2 AL-794: placebo/cohort) for 7 days in part 2. In part 3, 8 healthy volunteers from part 1 received 450 mg AL-794 ( n=6) or placebo ( n=2) following a high-fat meal. All dosing was done with an oral suspension. Blood and urine samples for pharmacokinetics were collected at scheduled times and analysed for ALS-033719 and ALS-033927 (inactive glucuronide) plasma concentrations using LC-MS/MS. Results ALS-033719 plasma concentrations increased dose proportionately up to 150 mg but less than proportionately above 150 mg. Steady-state was generally achieved by the third dose. ALS-033719 exposure increased following administration with a standard meal (19%–33%) or high-fat meal (3–3.6-fold). ALS-033927 was the major metabolite observed. Renal elimination was negligible (0.2%). Seventeen AL-794-treated healthy volunteers reported ≥1 treatment-emergent adverse event (TEAE; part 1: n=6, 24%; part 2: n=11, 69%). The most common TEAEs were headache (part 1: n=3; part 2: n=5) and dizziness (part 1: n=2; part 2: n=6). Conclusions AL-794 up to 200 mg twice daily achieved ALS-033719 exposures which are expected to be efficacious and were generally tolerated. Further studies are planned to characterize safety and antiviral activity.

Etravirine is a non-nucleoside reverse transcriptase inhibitor indicated in combination with other antiretrovirals for treatment-experienced HIV patients ≥6 years of age. Etravirine is primarily metabolized by cytochrome P450 (CYP) 2C9, CYP2C19, and CYP3A. This analysis determined the impact of concomitant antiretrovirals and CYP2C9/CYP2C19 phenotype on the pharmacokinetics of etravirine. We used 4728 plasma concentrations from 817 adult subjects collected from four clinical studies to develop the population pharmacokinetic model. The presence of atazanavir/ritonavir, lopinavir/ritonavir, darunavir/ritonavir, tenofovir disoproxil fumarate, or enfuvirtide together with the CYP2C9 and CYP2C19 phenotype and other demographics were evaluated. A one-compartment model with first-order input and a lag-time best described the data. Estimates of apparent total clearance (CL/F), apparent central volume of distribution (V c/F), first-order absorption rate constant (k a), and absorption lag-time were 41.7 L/h, 972 L, 1.16 h, and 1.32 h, respectively. Estimates of between-subject variability on CL/F, V c/F, and relative bioavailability (F) were 39.4 %CV (percentage coefficient of variation), 35.9 %CV and 35.5 %CV, respectively. Between-occasion variability on F was estimated to be 30.0 %CV. CL/F increased non-linearly with body weight and creatinine clearance (CLCR), and also varied based on CYP2C9/CYP2C19 phenotype. In this analysis, body weight, CLCR, and CYP2C9/CYP2C19 phenotype were found to describe some of the variability in CL/F. It was not possible to show an impact of concomitant antiretrovirals on the pharmacokinetics of etravirine for adults predominantly taking coadministered boosted protease inhibitors as a background antiretroviral regimen.

The aim of this study was to characterize the pharmacokinetic drug–drug interaction (DDI) between simeprevir (NS3/4A protease inhibitor) and odalasvir (NS5A inhibitor) after oral administration to support the design and dose selection of clinical studies with this combination for the treatment of chronic hepatitis C infection (HCV). Simeprevir and odalasvir plasma concentrations from 30 healthy subjects receiving these drugs in monotherapy as well as in combination were pooled and analyzed using a population pharmacokinetic modeling approach. Previous pharmacokinetic models developed to characterize the pharmacokinetics for each drug were used as starting point. The dual effect of simeprevir and odalasvir on their pharmacokinetic parameters was explored. Simulations were performed to assess the impact of the DDI on exposure parameters. In presence of odalasvir, the relative bioavailability of simeprevir increased by 26% and the apparent clearance was reduced following competitive inhibition depending on odalasvir plasma concentrations, with an inhibitory constant (Ki) estimated to be 1610 ng/mL. The apparent odalasvir clearance was reduced by simeprevir plasma concentrations following an Imax model, characterized by a maximum inhibitory effect of 46.7% and an IC50 of 257 ng/mL. Model-based simulations indicated that both Cmax and AUC24h increased for both drugs, when co-administered. The pharmacokinetic model adequately describes the time course of plasma concentrations and their variability when simeprevir and/or odalasvir were orally administered. This model can be used as a first step to predict the exposures of concomitant administration of simeprevir and odalasvir in HCV-infected subjects. Data from study AL355-602 (NCT02512562) were used for this analysis.

The aim of the current study was to characterize the time course of plasma concentrations of AL-335 and its main metabolites (ALS-022399 and ALS-022227) after oral administration in healthy and hepatitis C virus (HCV)-infected subjects, in monotherapy as well as in combination with simeprevir and/or odalasvir. AL-335, ALS-022399, and ALS-022227 plasma concentrations from subjects receiving 800 mg of AL-335 orally once daily (qd) as monotherapy or in combination were pooled and analyzed using a nonlinear mixed effect modeling approach. The typical values (between subject variability) of AL-335 and ALS-022399 apparent linear clearances were 3300 L/h (33.9%) and 1910 L/h (30.0%), respectively. ALS-022227 elimination was characterized as a nonlinear process, with typical values of Vmax,ALS-022227 and Km,ALS-022227 estimated to be 84,799 ng/h (14.9%) and 450.2 ng/mL, respectively. AL-335 and ALS-022399 plasma concentrations were increased more than 2-fold in presence of simeprevir and/or odalasvir, while the effect on ALS-022227 plasma concentrations was limited. The effect of simeprevir and/or odalasvir might be explained by their capacity to inhibit P-glycoprotein. Internal evaluation confirmed that the population pharmacokinetic model developed was deemed appropriate to describe the time course of AL-335, ALS-022399, and ALS-022227 plasma concentrations and their associated variability in both healthy and HCV-infected subjects, as well as the interaction effect of simeprevir and/or odalasvir over AL-335 and its metabolites in healthy subjects. This model can be used as a starting point to evaluate drug-drug interaction processes in HCV-infected patients and support the development of a direct-acting antiviral (DAA) combination.

This Phase I, open‐label, two‐group, fixed‐sequence study evaluated the pharmacokinetics and safety of AL‐335, odalasvir, and simeprevir in healthy subjects. Group 1 (n = 16) received AL‐335 800 mg once daily (QD) (days 1‐3, 11‐13, and 21‐23), simeprevir 150 mg QD (days 4‐23), and odalasvir 150 mg (day 14) followed by 50 mg QD (days 15‐23). Group 2 (n = 16) received the same AL‐335 regimen as in Group 1 plus odalasvir 150 mg (day 4) followed by 50 mg QD (days 5‐23) and simeprevir 150 mg QD (days 14‐23). Blood samples were collected to determine plasma concentrations of AL‐335 (prodrug) and its metabolites, ALS‐022399 (monophosphate precursor) and ALS‐022227 (parent nucleoside), odalasvir, and simeprevir. Thirty‐two subjects were enrolled. Odalasvir and simeprevir given alone, or in combination, increased AL‐335 area under plasma concentration‐time curve over 24 hours (AUC 0‐24 h) 3‐, 4‐, and 7‐ to 8‐fold, respectively; ALS‐022399 AUC 0‐24 h increased 2‐, 2‐, and 3‐fold, respectively. Simeprevir had no effect on ALS‐022227 AUC 0‐24 h, whereas odalasvir with/without simeprevir increased ALS‐022227 AUC 0‐24 h 1.5‐fold. AL‐335 had no effect on odalasvir or simeprevir pharmacokinetics. Odalasvir and simeprevir AUC 0‐24 h increased 1.5‐ to 2‐fold for both drugs when coadministered irrespective of AL‐335 coadministration. Study medications were well tolerated with no serious adverse events. One subject prematurely discontinued study drugs (unrelated event). This study defined the preliminary pharmacokinetic and safety profiles of the combination of AL‐335, odalasvir, and simeprevir in healthy subjects. These data support the further evaluation of this combination for the treatment of chronic hepatitis C virus infection.

Background AL-794 is an orally active prodrug of ALS-033719, which selectively inhibits the endonuclease domain of influenza virus A and B polymerase. Methods In a phase 1, double-blinded, randomized, placebo-controlled study, healthy subjects were inoculated intranasally with influenza virus (A/Perth/16/2009 H3N2) after confirmation of infection or on day 4. Subjects received 50 mg of AL-794, 150 mg of AL-794, or placebo twice daily for 5 days. Viral load, influenza symptoms, pharmacokinetics, and safety were evaluated. Results A total of 61 subjects were inoculated. In 42 infected subjects, the mean peak viral load for 50-mg AL-794 recipients, 150-mg AL-794 recipients, and placebo recipients was 3.54, 2.77, and 3.72 log10 50% tissue culture infectious doses (TCID50)/mL, respectively. The mean influenza viral load area under the curve in the corresponding treatment groups was 137, 87.5, and 142 log10 TCID50/mL·h, respectively, and the median time to virus nondetection was 117, 75.3, and 108 hours, respectively. AL-794 was well tolerated, and no viral resistance to ALS-033719 was identified. Conclusion Following oral administration of AL-794, significant dose-dependent antiviral activity was noted, with a greater decrease in viral load, symptoms, and mucus weight at the 150-mg dose, compared with the 50-mg dose, and no safety concerns for either dose or placebo. Clinical trials registration NCT02588521.

Background The nucleotide analog AL-335 is a pangenotypic hepatitis C virus (HCV) nonstructural protein (NS)5B inhibitor being evaluated as treatment for chronic HCV infection. Methods This three-part randomized, double-blind study evaluated the safety and pharmacokinetics of single and multiple ascending oral doses of AL-335. Healthy volunteers (HVs) received single doses of AL-335 (100-1,200 mg) or placebo in a fasted or fed (400 mg) state. Non-cirrhotic subjects (HCV genotype [GT]1-4) and GT1-infected subjects with Child Pugh A cirrhosis received multiple doses of AL-335 (400, 800, 1,200 mg) or placebo once daily (QD) for 7 days. Results Forty-eight HVs and 64 subjects with HCV GT1-4 were randomized and received treatment. AL-335 was well tolerated in HVs and HCV-infected subjects with/without cirrhosis. AL-335 was rapidly absorbed and converted to the metabolites ALS-022399 and ALS-022227. ALS-022227 exposure increased less than dose-proportionally and was unaffected by food, while AL-335 and ALS-022399 exposure increased with food by 85% and 50%, respectively, in HVs. Rapid and dose-dependent reductions in HCV-RNA were observed in GT1-infected subjects. In non-cirrhotic, GT1-4-infected subjects receiving AL-335 800 mg QD, potent antiviral activity was observed, regardless of genotype (mean maximum reductions in HCV-RNA of 4.0-4.8 log10 IU/mL). The same dose in GT1-infected cirrhotic subjects resulted in a 3.5 log10 IU/mL mean maximum reduction in HCV-RNA. Conclusions AL-335 was well tolerated when administered as single and multiple doses, with an acceptable pharmacokinetic profile. The drug also demonstrated potent antiviral activity in HCV GT1-4-infected subjects, including GT1-infected subjects with cirrhosis.

UNLABELLED Once-daily darunavir/ritonavir (800/100 mg), plus other antiretrovirals, is recommended for HIV-1-infected patients. Low therapy adherence is linked with poor outcomes. Pill burden can impact adherence. An 800-mg darunavir tablet would reduce pill burden. OBJECTIVES To assess the relative oral bioavailability (NCT01052883) and bioequivalence (NCT01308658) of a darunavir 800-mg tablet vs. 2 × 400-mg tablets. METHODS In two phase I, open-label, randomized, crossover, single-center studies, healthy volunteers received once-daily ritonavir (100 mg, days 1 - 5) and a single 800-mg darunavir dose: 2 × 400-mg tablets (reference) or 1 × 800- mg tablet (test) on day 3 and vice versa after a ≥ 7-day wash-out. Each study had fasted (n = 16 (bioavailability); n = 83 (bioequivalence)) and fed panels (n = 16; n = 45, respectively). Pharmacokinetic profiles and tolerability were assessed. RESULTS No volunteers discontinued for treatment-related reasons. Least-square mean ratios (test vs. reference) for darunavir maximum plasma concentrations (C(max)), area under the concentration-time curve from zero to infinity (AUC(0-∞)) were: 1.06 and 1.15 (bioavailability), and 1.02 and 1.00 (bioequivalence), respectively (fasted); 0.89 and 0.88 (bioavailability), and 0.96 and 0.98 (bioequivalence), respectively (fed). 90% confidence intervals (CI) were within 80.00 - 125.00%, except bioavailability AUC(0-∞) (fed and fasted conditions). Median time to C(max) was comparable for both formulations. No clinically relevant differences in adverse events or laboratory abnormalities occurred between formulations. CONCLUSIONS Bioequivalence was demonstrated for the 800-mg darunavir tablet (fasted and fed conditions). This formulation can reduce pill burden and potentially increase adherence for HIV-1-infected patients in whom once-daily darunavir/ritonavir 800/100 mg is appropriate.

The ability to dose antiretroviral agents once daily simplifies the often complex therapeutic regimens required for the successful treatment of HIV infection. Thus, once-daily dosing can lead to improved patient adherence to medication and, consequently, sustained virological suppression and reduction in the risk of emergence of drug resistance. Several trials have evaluated once-daily darunavir/ritonavir in combination with other antiretrovirals (ARTEMIS and ODIN trials) or as monotherapy (MONET, MONOI and PROTEA trials) in HIV-1-infected adults. Data from ARTEMIS and ODIN demonstrate non-inferiority of once-daily darunavir/ritonavir against a comparator and, together with pharmacokinetic data, have established the suitability of once-daily darunavir/ritonavir for treatment-naive and treatment-experienced patients with no darunavir resistance-associated mutations. The findings of ARTEMIS and ODIN have led to recent updates to treatment guidelines, whereby once-daily darunavir/ritonavir, given with other antiretrovirals, is now a preferred treatment option for antiretroviral-naive adult patients and a simplified treatment option for antiretroviral-experienced adults who have no darunavir resistance-associated mutations. Once-daily dosing with darunavir/ritonavir is an option for treatment-naive and for treatment-experienced paediatric patients with no darunavir resistance-associated mutations based on the findings of the DIONE trial and ARIEL substudy. This article reviews the pharmacokinetics, efficacy, safety and tolerability of once-daily boosted darunavir. The feasibility of darunavir/ritonavir monotherapy as a treatment approach for some patients is also discussed. Finally, data on a fixed-dose combination of 800/150 mg of darunavir/cobicistat once daily are presented, showing comparable darunavir bioavailability to that obtained with 800/100 mg of darunavir/ritonavir once daily.

Background & Aims NVR 3-778 is a first-in-class hepatitis B virus (HBV) capsid assembly modulator that can inhibit HBV replication. We performed a proof-of-concept study to examine the safety, pharmacokinetics, and antiviral activity of NVR 3-778 in patients with chronic HBV infection. Methods We performed a phase 1 study in 73 hepatitis B envelope antigen (HBeAg)-positive patients with chronic HBV infection without cirrhosis. In a 2-part study (part 1 in New Zealand and part 2 in Hong Kong, Singapore, Taiwan, Korea, and the United States), patients were randomly assigned to groups that were given oral NVR 3-778 (100 mg, 200 mg, or 400 mg daily or 600 mg or 1000 mg twice daily) or placebo for 4 weeks. Additional groups received combination treatment with pegylated interferon (pegIFN) and NVR 3-778 (600 mg twice daily) or pegIFN with placebo. Results Reductions in serum levels of HBV DNA and HBV RNA were observed in patients receiving ≥1200 mg/d NVR 3-778. The largest mean reduction in HBV DNA was observed in the group given NVR 3-778 plus pegIFN (1.97 log10 IU/mL), compared with the groups given NVR 3-778 or pegIFN alone (1.43 log10 IU/mL and 1.06 log10 IU/mL, respectively). The mean reduction in HBV RNA was also greatest in the group given NVR 3-778 plus pegIFN (2.09 log10 copies/mL), compared with the groups given NVR 3-778 or pegIFN alone (1.42 log10 copies/mL and 0.89 log10 copies/mL, respectively). There was no significant mean reduction in HBsAg during the 4-week treatment period. There were no discontinuations and no pattern of dose-related adverse effects with NVR 3-778. Conclusions In a phase 1 study of HBeAg-positive patients with chronic HBV infection without cirrhosis, NVR 3-778 was well tolerated and demonstrated antiviral activity. The agent reduced serum levels of HBV DNA and HBV RNA, to the greatest extent in combination with pegIFN. The observed reductions in HBV RNA confirmed the novel mechanism of NVR 3-778. Clinicaltrials.gov no. NCT02112799 (single-center) and NCT02401737 (multicenter).

Objectives: Drug– drug interactions between etravirine and rifabutin or clarithromycin were examined in two separate open-label, randomized, two-period, crossover trials in HIV-negative, healthy volunteers. Methods: Rifabutin study: 16 participants received 300 mg of rifabutin once daily (14 days) and then 800 mg of etravirine twice daily (Phase 2 formulation; 21 days) plus 300 mg of rifabutin once daily (days 8 –21). Clarithromycin study: 16 participants received 200 mg of etravirine twice daily (commercial formulation; 8 days) and then 500 mg of clarithromycin twice daily (13 days) plus 200 mg of etravirine twice daily (days 6– 13). A 14 day washout period between treatments was mandatory in both studies. Full pharmacokinetic profiles of each drug and safety/tolerability were assessed. Results: Rifabutin decreased etravirine exposure by 37%; etravirine decreased rifabutin and 25-O-desacetyl rifabutin exposure by 17%. Clarithromycin increased etravirine exposure by 42%, whereas etravirine decreased clarithromycin exposure by 39% and increased 14-OH clarithromycin exposure by 21%. No serious adverse events were reported in either trial. Conclusions: Short-term etravirine coadministration with rifabutin or clarithromycin was well tolerated. Etravirine can be coadministered with 300 mg of rifabutin once daily in the absence of an additional potent cytochrome P450 inducer. No dose adjustments are required upon etravirine/clarithromycin coadministration, but alternatives to clarithromycin are recommended when used for Mycobacterium avium complex prophylaxis or treatment.

Objectives Three studies were conducted to assess the pharmacokinetics, methods of administration and ease of swallowability of etravirine tablets. Methods Two randomized studies in healthy adults investigated the single-dose pharmacokinetics of etravirine in various dosage strengths and the effects of dispersion in water and film-coating. A third study explored swallowability of etravirine 200-mg tablets in HIV-infected patients. First study: 37 volunteers received 1 × 100-mg non-coated tablet (reference), 4 × 25-mg noncoated tablets and 1 × 100-mg non-coated tablet dispersed in 100 ml water. Second study: 24 volunteers received 2 × 100-mg non-coated tablets (reference), 2 × 100-mg coated tablets, 1 × 200-mg non-coated and 1 × 200-mg coated tablet. Pharmacokinetic parameters were determined using non-compartmental analysis and least square means (LSM) ratios and 90% confidence intervals (CI) were calculated. Third study: 49 virologically-suppressed patients already on an etravirine-containing regimen rated the swallowability of two etravirine formulations (200-mg non-coated and 200-mg coated tablets). Results In the first study LSM ratios (90% CI) for the etravirine area under the plasma concentration-time curve (AUC) administered either as 4 × 25-mg tablets or 100-mg tablet dispersed were: 0.91 (0.85 to 0.98) and 0.97 (0.90 to 1.03), respectively. In the second study, when comparing a 200-mg non-coated and coated tablet to 2 × 100-mg non-coated tablets, LSM ratios for etravirine AUC were 98 to 99%. In the third study, more patients rated the 200-mg than the 100-mg tablets as acceptable to swallow (70% vs. 43%). Conclusions Comparable etravirine exposures were observed regardless of formulation or method of administration (i.e., dispersion); 200-mg tablets were rated as easier to swallow than 100-mg tablets.

Objectives Antiretroviral therapy during pregnancy is recommended to reduce the risk of mother-to-child transmission of HIV and for maternal care management. Physiological changes during pregnancy can affect pharmacokinetics, potentially altering pharmacological activity. We therefore evaluated the pharmacokinetics of twice-daily (bid) darunavir in HIV-1-infected pregnant women. Methods HIV-1-infected pregnant women receiving an antiretroviral regimen containing darunavir/ritonavir 600/100 mg bid were enrolled in this study. Total and unbound darunavir and total ritonavir plasma concentrations were obtained over 12 h during the second and third trimesters and postpartum. Total darunavir and ritonavir plasma concentrations were determined using a validated high-performance liquid chromatography tandem mass spectrometry assay and unbound darunavir was determined using 14C-darunavir-fortified plasma. Pharmacokinetic parameters were derived using noncompartmental analysis. Results Data were available for 14 women. The area under the plasma concentration–time curve from 0 to 12 h (AUC12h) for total darunavir was 17–24% lower during pregnancy than postpartum. The AUC12h for unbound darunavir was minimally reduced during pregnancy vs. postpartum. The minimum plasma concentration (Cmin) of total and unbound darunavir was on average 43–86% and 10–14% higher, respectively, during pregnancy vs. postpartum. The antiviral response (

Etravirine is currently approved for HIV treatment-experienced patients at a dose of 200 mg twice daily. The long terminal elimination half-life of etravirine should support once-daily dosing.In the double-blind 48-week SENSE trial, 157 antiretroviral treatment-naïve patients were randomly assigned to receive etravirine 400 mg once daily (n = 79) or efavirenz 600 mg once daily (n = 78), plus 2 nucleoside reverse transcriptase inhibitors (NRTIs). Sparse sampling for etravirine plasma concentrations was conducted during the 48-week trial. Area under the curve over the dosing interval (AUC24h) and trough concentration (C0h) were estimated using a population pharmacokinetic model and compared with previous results using the 200-mg twice-daily dosage. The relationship between etravirine AUC24h and C0h with efficacy and safety was also assessed.By week 48, the percentage of patients in the etravirine arm with HIV RNA50 copies/ mL was 75.9% in the intent-to-treat switch equals failure analysis and 92.3% in the on-treatment analysis; no patient developed genotypic or phenotypic resistance to NRTIs or non-nucleoside reverse transcriptase inhibitors (NNRTIs) after virologic failure. Seventy-one subjects had evaluable etravirine pharmacokinetics. The median (interquartile range) of etravirine AUC24h and C0h were 12,447 (8,261-15,652) ng•h/mL and 330 (188-472) ng/mL, respectively. There was no correlation between etravirine exposure and virologic response or adverse events.In the SENSE trial, etravirine 400 mg once daily achieved similar exposures to historical reference data on etravirine when dosed at 200 mg twice daily. There was no apparent relationship between the pharmacokinetics of etravirine and virologic response or adverse events.

Etravirine (formerly TMC125) is a non-nucleoside reverse transcriptase inhibitor (NNRTI) with activity against wild-type and NNRTI-resistant strains of HIV-1. Etravirine has been approved in several countries for use as part of highly active antiretroviral therapy in treatment-experienced patients. In vivo, etravirine is a substrate for, and weak inducer of, the hepatic cytochrome P450 (CYP) isoenzyme 3A4 and a substrate and weak inhibitor of CYP2C9 and CYP2C19. Etravirine is also a weak inhibitor of P-glycoprotein. An extensive drug-drug interaction programme in HIV-negative subjects has been carried out to assess the potential for pharmacokinetic interactions between etravirine and a variety of non-antiretroviral drugs. Effects of atorvastatin, clarithromycin, methadone, omeprazole, oral contraceptives, paroxetine, ranitidine and sildenafil on the pharmacokinetic disposition of etravirine were of no clinical relevance. Likewise, etravirine had no clinically significant effect on the pharmacokinetics of fluconazole, methadone, oral contraceptives, paroxetine or voriconazole. No clinically relevant interactions are expected between etravirine and azithromycin or ribavirin, therefore, etravirine can be combined with these agents without dose adjustment. Fluconazole and voriconazole increased etravirine exposure 1.9- and 1.4-fold, respectively, in healthy subjects, however, no increase in the incidence of adverse effects was observed in patients receiving etravirine and fluconazole during clinical trials, therefore, etravirine can be combined with these antifungals although caution is advised. Digoxin plasma exposure was slightly increased when co-administered with etravirine. No dose adjustments of digoxin are needed when used in combination with etravirine, however, it is recommended that digoxin levels should be monitored. Caution should be exercised in combining rifabutin with etravirine in the presence of certain boosted HIV protease inhibitors due to the risk of decreased exposure to etravirine. Although adjustments to the dose of clarithromycin are unnecessary for the treatment of most infections, the use of an alternative macrolide (e.g. azithromycin) is recommended for the treatment of Mycobacterium avium complex infection since the overall activity of clarithromycin against this pathogen may be altered when co-administered with etravirine. Dosage adjustments based on clinical response are recommended for clopidogrel, HMG-CoA reductase inhibitors (e.g. atorvastatin) and for phosphodiesterase type-5 inhibitors (e.g. sildenafil) because changes in the exposure of these medications in the presence of co-administered etravirine may occur. When co-administered with etravirine, a dose reduction or alternative to diazepam is recommended. When combining etravirine with warfarin, the international normalized ratio (INR) should be monitored. Systemic dexamethasone should be co-administered with caution, or an alternative to dexamethasone be found as dexamethasone induces CYP3A4. Caution is also warranted when co-administering etravirine with some antiarrhythmics, calcineurin inhibitors (e.g. ciclosporin) and antidepressants (e.g. citalopram). Co-administration of etravirine with some antiepileptics (e.g. carbamazepine and phenytoin), rifampicin (rifampin), rifapentine or preparations containing St John's wort (Hypericum perforatum) is currently not recommended as these are potent inducers of CYP3A and/or CYP2C and may potentially decrease etravirine exposure. Antiepileptics that are less likely to interact based on their known pharmacological properties include gabapentin, lamotrigine, levetiracetam and pregabalin. Overall, pharmacokinetic and clinical data show etravirine to be well tolerated and generally safe when given in combination with non-antiretroviral agents, with minimal clinically significant drug interactions and no need for dosage adjustments of etravirine in any of the cases, or of the non-antiretroviral agent in the majority of cases studied.

Etravirine is an effective and well-tolerated recently approved non-nucleoside reverse transcriptase inhibitor (NNRTI) for HIV type-1-infected patients with previous antiretroviral treatment experience. Considering the importance of combining antiretrovirals for their optimal use in treating HIV, a number of drug–drug interactions with etravirine and other antiretrovirals have been evaluated. Etravirine is a weak inducer of cytochrome P450 (CYP)3A and a weak inhibitor of CYP2C9/CYP2C19 and P-glycoprotein, and although etravirine is metabolized by the CYP enzyme system, the extent of clinically relevant interactions with other antiretrovirals is limited. Etravirine can be combined with all currently available nucleoside/nucleotide reverse transcriptase inhibitors without dose adjustments, but not with other NNRTIs. Available data indicate that etravirine can be coadministered with most of the currently available ritonavir-boosted HIV protease inhibitors. Coadministration with tipranavir/ritonavir or unboosted HIV protease inhibitors is not recommended because of clinically relevant changes in exposure to etravirine or the coadministered HIV protease inhibitor, respectively. Etravirine can be coadministered with the integrase inhibitors elvitegravir/ritonavir or raltegravir, and with the fusion inhibitor enfuvirtide, without dose adjustments. Dose adjustment of the C–C chemokine receptor type-5 antagonist maraviroc is required, with the type of adjustment depending on whether a boosted HIV protease inhibitor is included in the regimen. In conclusion, etravirine can be combined with most antiretrovirals, with no clinically meaningful effect on drug exposure or safety/tolerability profiles.

Etravirine is a next-generation non-nucleoside reverse transcriptase inhibitor (NNRTI) developed for the treatment of HIV-1 infection. It has a high genetic barrier to the emergence of viral resistance, and maintains its antiviral activity in the presence of common NNRTI mutations. The pharmacokinetics of etravirine in HIV-infected patients at the recommended dosage of 200 mg twice daily demonstrates moderate intersubject variability and no time dependency. Due to substantially lower exposures when taken on an empty stomach, etravirine should be administered following a meal. The drug is highly protein bound (99.9%) to albumin and alpha(1)-acid glycoprotein and shows a relatively long elimination half-life of 30-40 hours. Etravirine is metabolized by cytochrome P450 (CYP) 3A, 2C9 and 2C19; the metabolites are subsequently glucuronidated by uridine diphosphate glucuronosyltransferase. Renal elimination of etravirine is negligible. Etravirine has the potential for interactions by inducing CYP3A and inhibiting CYP2C9 and 2C19; it is a mild inhibitor of P-glycoprotein but not a substrate. The drug interaction profile of etravirine has been well characterized and is manageable. No dosage adjustments are needed in patients with renal impairment or mild to moderate hepatic impairment. Race, sex, bodyweight and age do not affect the pharmacokinetics of etravirine. In the two phase III trials DUET-1 and DUET-2, no relationship was demonstrated between the pharmacokinetics of etravirine and the primary efficacy endpoint of viral load below 50 copies/mL or the safety profile of etravirine.

Background Etravirine, a non-nucleoside reverse transcriptase inhibitor (NNRTI) active against NNRTI-resistant HIV, is an inducer of CYP3A4 and an inhibitor of CYP2C9/19. Study Design The effect of etravirine on the pharmacokinetics and pharmacodynamics of ethinylestradiol and norethindrone was assessed in 30 HIV-negative females. Following a run-in cycle with ethinylestradiol/norethindrone, the pharmacokinetics of ethinylestradiol and norethindrone was assessed on Day 15 of Cycle 2. Etravirine 200 mg bid was coadministered on Day 1 to Day 15 of Cycle 3, with pharmacokinetic assessments of ethinylestradiol, norethindrone and etravirine on Day 15. Results When combined with etravirine, the least-squares means (LSM) ratios (90% confidence interval) for ethinylestradiol AUC 24h , C max and C min were 1.22 (1.13���1.31), 1.33 (1.21���1.46) and 1.09 (1.01���1.18), respectively, compared to administration alone. LSM ratios for norethindrone parameters were 0.95 (0.90���0.99), 1.05 (0.98���1.12) and 0.78 (0.68���0.90), respectively. Conclusion These changes are not considered clinically relevant. No loss in contraceptive efficacy is expected when coadministered with etravirine.

Etravirine, a next-generation nonnucleoside reverse transcriptase inhibitor, and raltegravir, an integrase strand transfer inhibitor, have separately demonstrated potent activity in treatment-experienced, human immunodeficiency virus (HIV)-infected patients. An open-label, sequential, three-period study with healthy, HIV-seronegative subjects was conducted to assess the two-way interaction between etravirine and raltegravir for potential coadministration to HIV-infected patients. In period 1, 19 subjects were administered 400 mg raltegravir every 12 h (q12 h) for 4 days, followed by a 4-day washout; in period 2, subjects were administered 200 mg etravirine q12 h for 8 days; and in period 3, subjects were coadministered 400 mg raltegravir and 200 mg etravirine q12 h for 4 days. There was no washout between periods 2 and 3. Doses were administered with a moderate-fat meal. Etravirine had only modest effects on the pharmacokinetics of raltegravir, while raltegravir had no clinically meaningful effect on the pharmacokinetics of etravirine. For raltegravir coadministered with etravirine relative to raltegravir alone, the geometric mean ratio (GMR) and 90% confidence interval (CI) were 0.90 and 0.68 to 1.18, respectively, for the area under the concentration curve from 0 to 12 h (AUC0-12), 0.89 and 0.68 to 1.15, respectively, for the maximum concentration of drug in serum (Cmax), and 0.66 and 0.34 to 1.26, respectively, for the trough drug concentration (C12); the GMR (90% CI) for etravirine coadministered with raltegravir relative to etravirine alone was 1.10 (1.03, 1.16) for AUC0-12, 1.04 (0.97, 1.12) forCmax, and 1.17 (1.10, 1.26) forC12. All drug-related adverse clinical experiences were mild and generally transient in nature. No grade 3 or 4 adverse experiences or discontinuations due to adverse experiences occurred. Coadministration of etravirine and raltegravir was generally well tolerated; the data suggest that no dose adjustment for either drug is necessary.

Background: Etravirine (TMC125), a next-generation nonnucleoside reverse transcriptase inhibitor, has shown antiviral efficacy in 2 large Phase 3 trials. In vitro and in vivo studies have shown that etravirine is not associated with proarrhythmic potential. Electrocardiograms (ECGs) from healthy and HIV 1–infected volunteers showed no clinically relevant changes. Objective: To evaluate the effect of 2 etravirine dosing regimens on QT/corrected QT interval (QTc) in HIV-negative volunteers and assess pharmacokinetic and additional safety parameters. Methods: A double-blind, double-dummy, randomized, placebo- and active-controlled, 4-period crossover trial was conducted in 41 HIV-negative volunteers. Participants received 4 regimens: etravirine 200 mg twice daily, etravirine 400 mg once daily, moxifloxacin 400 mg once daily (positive control), and placebo in separate 8-day sessions, with each followed by a washout period of 14 or more days. On days -1, 1, and 8 of each session, ECGs were recorded at 11 time points over 12 hours. Pharmacokinetic profiles of etravirine regimens were evaluated and safety was assessed. Results: Thirty-seven subjects completed the study. For etravirine, the upper limit of the 90% CIs of mean time-matched differences in QTc determined using Fridericia's formula (QTcF) was below 10 msec at all time points, the threshold for prolonged QT as defined by regulatory guidelines. The maximum mean (90% CI) difference of time-matched changes in QTcF versus placebo on day 1 was +0.1 msec (–2.6 to 2.9), -0.2 msec (-2.6 to 2.1), and +10.1 msec (7.3 to 12.8) for etravirine 200 mg twice daily, etravirine 400 mg once daily, and moxifloxacin, respectively. On day 8, these values were +0.6 msec (-2.1 to 3.3), -1.0 msec (-4.4 to 2.5), and +10.3 msec (6.8 to 13.9), respectively. Etravirine produced no clinically significant changes in other ECG parameters. No significant differences between males and females were observed. Both etravirine regimens had similar pharmacokinetic exposure and safety profiles. Conclusions: Etravirine does not prolong the QTc interval. No clinically relevant ECG changes were observed in HIV-negative volunteers. Short-term dosing of etravirine in HIV-negative volunteers was generally safe and well tolerated.

TMC125 is a nonnucleoside reverse transcriptase inhibitor (NNRTI) with potent in vitro activity against wild-type and NNRTI-resistant HIV-1. TMC125 is an inducer of CYP3A and an inhibitor of CYP2C. This trial evaluated the effect of TMC125 on the pharmacokinetics and pharmacodynamics of methadone. In an open-label, add-on, 1-way interaction trial, 16 male HIV-negative volunteers on stable methadone maintenance therapy received 100 mg TMC125 bid for 14 days. Plasma concentrations and pharmacokinetic parameters of R- and S-methadone isomers were determined on days -1, 7, and 14 and of TMC125 on days 7 and 14. Safety and tolerability were assessed. The LSmeans ratios (90% confidence interval) for A UC 24h , C max , and C min of the pharmacologically active R-methadone were 1.08 (1.02-1.13), 1.03 (0.97-1.09), and 1.12 (1.05-1.19), respectively, on day 7 and 1.06 (0.99-1.13), 1.02 (0.96-1.09), and 1.10 (1.02-1.19), respectively, on day 14 compared with methadone alone. No withdrawal symptoms were observed; dose adjustment of methadone was not required. The concomitant administration of TMC125 and methadone was generally safe and well tolerated. TMC125 has no clinically relevant effect on the pharmacokinetics or pharmacodynamics of methadone. No dose adjustment for methadone is anticipated when coadministered with TMC125.

ObjectiveTo evaluate the pharmacokinetics of TMC125 (etravirine) and darunavir (DRV) with low-dose ritonavir (DRV/r).DesignOpen-label, randomized, two-way crossover Phase I trial.MethodsThirty-two HIV-negative volunteers were randomized 1:1 to two panels. All received TMC125 100 mg twice daily for 8 days and, after 14 days washout, DRV/r 600/100 mg twice daily for 16 days. During days 9–16, TMC125 100 or 200 mg twice daily was coadministered (Panel I or II, respectively).ResultsTwenty-three volunteers completed the trial. With DRV/r coadministration, mean exposure (area under the plasma concentration-time curve from 0 to 12 h [AUC12h]) to TMC125 given as 100 mg twice daily was decreased by 37%; maximum and minimum plasma concentrations (Cmaxand Cmin) were decreased by 32% and 49%, respectively. For TMC125 200 mg twice daily coadministered with DRV/r, AUC12h, Cmaxand Cminof TMC125 were 80%, 81% and 67% greater, respectively, versus TMC125 100mg twice daily alone. DRV pharmacokinetics were unchanged except a 15% increase in AUC12hwhen given with TMC125 200 mg twice daily.ConclusionsNo clinically relevant changes in DRV pharmacokinetics were observed when combined with TMC125; therefore DRV dose adjustment is not required. Coadministration of TMC125 100 mg twice daily with DRV/r decreased TMC125 exposure by 37%. The increase of TMC125 exposure by 80% when given as 200 mg twice daily reflects the higher dose and the interaction with DRV/r. The magnitude of this interaction is comparable to TMC125 interactions with other boosted PIs observed in Phase IIb trials in HIV-1-infected patients. As these trials demonstrated TMC125 efficacy, no dose adjustment of TMC125 is needed when combined with DRV/r.

PIANO (NCT00665847) investigated etravirine pharmacokinetics, efficacy, and safety in children and adolescents. Treatment-experienced, HIV-1-infected patients (≥6 to18 years) received etravirine 5.2 mg/kg twice daily (maximum 200 mg twice daily) plus background antiretrovirals. A population pharmacokinetic model was developed, and etravirine C

A current focus in HIV management is improving adherence by minimizing pill burden with convenient formulations, including fixed-dose combinations (FDCs). Darunavir, a HIV protease inhibitor, co-administered with low-dose ritonavir (800/100 mg once daily), is recommended in guidelines in combination with other antiretrovirals for HIV patients with no darunavir resistance-associated mutations. Cobicistat is an alternative agent to ritonavir for boosting plasma drug levels of darunavir among other antiretrovirals. Cobicistat is a more specific cytochrome P450 3A inhibitor than ritonavir without enzyme-inducing properties. This review describes the differing effects of cobicistat and ritonavir on metabolic enzymes, which explains their differing drug-drug interactions, and summarizes some of the studied drug-drug interactions for cobicistat. It also outlines the clinical development and data for a once-daily darunavir/cobicistat FDC. This FDC thus allows for a once-daily treatment regimen (including background antiretrovirals) with reduced pill burden.

BACKGROUND ARIEL (Darunavir in treatment-experienced pediatric population) was a phase II, open-label study assessing safety and antiviral activity of darunavir/ritonavir twice daily with an optimized background regimen (OBR) in treatment-experienced, HIV-1-infected pediatric patients (3 to

Nucleoside- and nucleotide-analogue reverse-transcriptase inhibitors (NRTIs) require intracellular phosphorylation for anti-human immunodeficiency virus (HIV) activity and toxicity. Long-term toxicities associated with NRTIs may be related to overactivation of this process. In vitro experiments have shown increased rates of NRTI and endogenous nucleoside phosphorylation to be associated with cellular activation. Patients with advanced HIV disease often have overexpression of cytokines, which corresponds to an elevated cellular activation state. These patients also have higher rates of NRTI phosphorylation and NRTI toxicity, suggesting an interaction between a proinflammatory biological state, NRTI phosphorylation, and toxicity. Studies suggest that women may have higher rates of NRTI phosphorylation than do men, as well as increased risk for NRTI-induced toxicity. Future research is needed to understand the NRTI activation process and improve the long-term toxicity profile of NRTIs. Such research should include comparisons of NRTI phosphorylation according to sex and cellular activation state (i.e., elevated vs. low).

Objectives: To demonstrate the feasibility of a concentration-controlled approach to combination antiretroviral therapy, and to compare the virological responses and safety of this strategy versus conventional fixed-dose therapy. Design: A prospective, randomized, 52 week, open-label trial of concentration-controlled compared with conventional close zidovudine, lamivudine, and indinavir therapy conduced in a university-based general clinical research center in the United States. Patients: Forty antiretroviral-naive individuals with plasma HIV-RNA levels > 5000 copies/ml. Interventions: Zidovudine, lamivudine, and indinavir plasma concentrations were measured in all participants. Doses were adjusted in those assigned to concentration-controlled therapy to achieve levels equal to or greater than target values. Main outcome measures: The proportion of patients who achieved the desired drug concentrations, the proportion of patients with HIV-RNA levels < 50 copies/ml at week 52, and safety and tolerance in the concentration-controlled versus conventional therapy arms. Results: Significantly more concentration-controlled recipients achieved the desired concentration targets for all three drugs: 15 of 16 concentration-controlled recipients compared with nine of 17 conventional recipients (P = 0.017) had HIV-RNA levels < 50 copies/ml at week 52. No difference was observed in the occurrence of drug-related clinical events or laboratory abnormalities between the two treatment arms. Conclusion: Concentration-controlled therapy implemented simultaneously for three antiretroviral agents was feasible, as well tolerated as conventional therapy, and resulted in a greater proportion of recipients with HIV-RNA levels < 50 copies/ml after 52 weeks. These findings provide a scientific basis to challenge the accepted practice of administering the same dose of antiretroviral agents to all adults, ignoring the concentrations actually achieved.

Background Darunavir requires pharmacokinetic enhancement to increase its bioavailability. Cobicistat is potentially an alternative pharmacokinetic booster to ritonavir. Bioequivalence of a darunavir/cobicistat fixed-dose combination (FDC) versus darunavir and cobicistat co-administered as single agents and the effect of a high-fat meal on the pharmacokinetics of the FDC were evaluated. Methods In this Phase I, open-label, randomized, three-panel, crossover study (NCT01619527), healthy volunteers received a single dose of darunavir (800 mg) with cobicistat (150 mg) as either an FDC or as single agents co-administered under fasted (panel 1, n=74) or fed (breakfast, panel 2, n=40) conditions, or as the FDC under fasted versus fed (high-fat breakfast) conditions (panel 3, n=19), with a ≥7 day washout period between treatments. Pharmacokinetic profiles, safety and tolerability were assessed. Results 90% confidence intervals of the least square mean ratios for darunavir and cobicistat maximum plasma concentration and area under the plasma concentration–time curve (AUC) were all within 80.00% and 125.00% in panels 1 and 2. Administration of the FDC with a high-fat breakfast significantly increased darunavir maximum plasma concentration 2.27-fold and AUC 1.63–1.70-fold, whereas cobicistat pharmacokinetics were unaffected. No volunteers discontinued due to adverse events (AEs). All AEs were grade 1 or 2. Overall, 27 (20%) and 26 (20%) volunteers had ≥1 AE at least possibly related to darunavir and cobicistat, respectively. Conclusions Bioequivalence of the darunavir/cobicistat 800/150-mg FDC was demonstrated versus darunavir and cobicistat co-administered as single agents under fasted or fed conditions. Food increased darunavir exposure, therefore, darunavir/cobicistat should be administered with food.

BACKGROUND Twice-daily darunavir/ritonavir is indicated in treatment-experienced children (≥3 years). This study assessed once-daily administration in treatment-naive adolescents. METHODS Phase 2, 48-week, open-label, single-arm study evaluating pharmacokinetics, safety and efficacy of once-daily darunavir/ritonavir 800/100 mg in treatment-naive, HIV-1-infected adolescents (≥12 to

Objective This paper reviews the function of the mitochondria and the mechanisms by which nucleoside and nucleotide reverse transcriptase inhibitors (NRTIs) cause mitochondrial toxicity. Background Highly active antiretroviral therapy (HAART) reduces rates of morbidity and mortality due to HIV disease. However, long-term treatment with these drugs may be associated with adverse effects. Nucleoside and nucleotide analogues are potent inhibitors of HIV reverse transcriptase and have become the cornerstone of HAART. Unfortunately, these drugs have also been shown to inhibit cellular polymerases, most notably mitochondrial DNA polymerase γ. Results Studies of the NRTIs in enzyme assays and cell cultures demonstrate the following hierarchy of mitochondrial DNA polymerase γ inhibition: zalcitabine ≥ didanosine ≥ stavudine > lamivudine > zidovudine > abacavir. In vitro investigations have also documented impairment of the mitochondrial enzymes adenylate kinase and the adenosine diphosphate/adenosine triphosphate translocator. Inhibition of DNA polymerase γ and other mitochondrial enzymes can gradually lead to mitochondrial dysfunction and cellular toxicity. The clinical manifestations of NRTI-induced mitochondrial toxicity resemble those of inherited mitochondrial diseases (ie, hepatic steatosis, lactic acidosis, myopathy, nephrotoxicity, peripheral neuropathy, and pancreatitis). Fat redistribution syndrome, or HIV-associated lipodystrophy, is another side effect attributed in part to NRTI therapy. The morphologic and metabolic complications of this syndrome are similar to those of the mitochondrial disorder known as multiple symmetric lipomatosis, suggesting that this too may be related to mitochondrial toxicity. The pathophysiology of less common adverse effects of nucleoside analogue therapy, such as diabetes, ototoxicity, and retinal lesions, may be related to mitochondrial dysfunction but have not been adequately studied. Conclusion NRTIs can block both HIV reverse transcriptase and mitochondrial DNA polymerase γ. Inhibition of the latter enzyme is the most likely cause of the adverse effects associated with these drugs.

The pharmacology, pharmacokinetics, efficacy, adverse effects, drug interactions, and dosage and administration of protease inhibitors are reviewed. Protease inhibitors are a novel class of drugs used for the treatment of human immunodeficiency virus (HIV) infection. Saquinavir, ritonavir, indinavir, and nelfinavir have been approved in the United States; several other agents are under development. Protease inhibitors selectively block HIV protease, an enzyme involved in the later stages of HIV replication. Various pharmacokinetic differences exist among these agents, including differences in bioavailability, protein binding, and drug interactions. The drugs undergo extensive hepatic metabolism; dosage adjustments should be considered for patients with hepatic dysfunction. Clinical trials have shown protease inhibitors to be effective in reducing HIV RNA levels and increasing CD4+ lymphocyte counts. When protease inhibitors are used in combination with other antiretroviral agents, an additional beneficial effect on these markers occurs. Adverse effects of saquinavir and nelfinavir include mild gastrointestinal disturbances such as diarrhea. Ritonavir is less well tolerated because of gastrointestinal disturbances and circumoral and peripheral paresthesia. Indinavir has been associated with nephrolithiasis and asymptomatic hyperbilirubinemia. The development of resistance to protease inhibitors may be related to suboptimal dosages, noncompliance, or partial compliance. Protease inhibitors are potent and highly selective agents that block a critical step in HIV replication. They are effective and relatively well tolerated, but they are expensive, have extensive drug interaction profiles, and require careful compliance with the prescribed regimen.

This study compared the bioavailability of two candidate fixed-dose combinations (FDCs: G003 and G004) of darunavir/cobicistat 800/150 mg with that of darunavir 800 mg and ritonavir 100 mg coadministered as single agents. Short-term safety and tolerability of the FDC formulations were also assessed. This open-label trial included 36 healthy volunteers and assessed steady-state pharmacokinetics of darunavir over 3 randomized, 10-day treatment sequences, under fed conditions. Blood samples for determination of plasma concentrations of darunavir and cobicistat or ritonavir were taken over 24 hours on day 10 and analyzed by liquid-chromatography tandem mass-spectroscopy. Darunavir AUC24h following administration of the FDCs (G003: 74,780 ng ∙ h/mL and G004: 76,490 ng ∙ h/mL) was comparable to that following darunavir/ritonavir (78,410 ng ∙ h/mL), as was Cmax (6,666 and 6,917 ng/mL versus 6,973 ng/mL, respectively). Modestly lower C0h (1,504 and 1,478 ng/mL versus 2,015 ng/mL) and Cmin (1,167 and 1,224 ng/mL versus 1,540 ng/mL) values were seen with the FDCs. Short-term tolerability of the FDCs was comparable to that of darunavir/ritonavir when administered as single agents. The most common adverse events reported were headache, gastrointestinal upset, or rash. Cobicistat is an effective pharmacoenhancer of darunavir when administered as an FDC. Short-term administration of darunavir/ritonavir or darunavir/cobicistat was generally well tolerated.

Coinfection with human immunodeficiency virus (HIV) and hepatitis C virus (HCV) may require treatment with an HIV non-nucleoside reverse transcriptase inhibitor (NNRTI), for example, rilpivirine or etravirine, and an HCV direct-acting antiviral drug such as telaprevir. In a two-panel, two-way, crossover study, healthy volunteers were randomized to receive etravirine 200 mg twice daily ± telaprevir 750 mg every 8 hours or rilpivirine 25 mg once daily ± telaprevir 750 mg every 8 hours. Pharmacokinetic assessments were conducted for each drug at steady-state when given alone and when coadministered; statistical analyses were least-square means with 90% confidence intervals. Telaprevir minimum plasma concentration (Cmin), maximum plasma concentration (Cmax), and area under the concentration-time curve (AUC) decreased 25%, 10%, and 16%, respectively, when coadministered with etravirine and 11%, 3%, and 5%, respectively, when coadministered with rilpivirine. Telaprevir did not affect etravirine pharmacokinetics, but increased rilpivirine Cmin, Cmax, and AUC by 93%, 49%, and 78%, respectively. Both combinations were generally well tolerated. The small decrease in telaprevir exposure when coadministered with etravirine is unlikely to be clinically relevant. The interaction between telaprevir and rilpivirine is not likely to be clinically relevant under most circumstances. No dose adjustments are deemed necessary when they are coadministered.

This 2-part, phase 1, open-label, randomized, crossover study (NCT00752310) assessed ritonavir-boosted darunavir bioavailability (oral suspension vs. tablets), and steady-state darunavir pharmacokinetics (suspension). Part 1: 20 healthy adults randomly received 3 treatments with a ≥7-day washout between treatments; twice-daily ritonavir (100 mg, days 1-5) with darunavir (600 mg, day 3) as 2 × 300-mg tablets (fed, reference), or 6 mL of a 100-mg/mL suspension (fed or fasted, test). Part 2: 18 healthy volunteers received twice-daily darunavir (suspension, 600 mg days 1-6, one dose day 7) with twice-daily ritonavir (100 mg, days 1-9). Darunavir pharmacokinetics were evaluated (part 1 day 3; part 2 day 7). Safety/tolerability were assessed. In part 1, 90% confidence intervals for darunavir Cmax and AUC were all within 80-125% for suspension (fed or fasted) versus tablets (fed). Steady-state darunavir (suspension) pharmacokinetics in part 2 were similar to historic controls (tablets). No clinically relevant differences in adverse events or laboratory abnormalities occurred between treatments. Darunavir administered as an oral suspension or tablets (both with low-dose ritonavir) showed comparable bioavailability in healthy adults after a single dose. Steady-state darunavir pharmacokinetics (suspension, 600/100 mg twice daily) were consistent with historic controls; this formulation is considered suitable for pediatric use and for adults who cannot swallow tablets.

OBJECTIVES To evaluate the pharmacokinetics, weight-based dose selection and short-term safety and tolerability of etravirine in HIV-1-infected children and adolescents. DESIGN Phase I, nonrandomized, open-label study in two stages. METHODS Children and adolescents aged at least 6 years to 17 years or less on a stable lopinavir/ritonavir-based antiretroviral regimen with HIV-1 RNA plasma viral load less than 50 copies/ml were enrolled. In both stages, etravirine (4 mg/kg twice daily in stage I, 5.2 mg/kg twice daily in stage II), added to the existing antiretroviral regimen, was administered for 7 days followed by a morning dose and 12-h pharmacokinetic assessment on day 8. Pharmacokinetic parameters were determined using noncompartmental analysis. Data were compared with those previously established in HIV-1-infected adults on a similar etravirine (200 mg twice daily) combination antiretroviral regimen. RESULTS Twenty-one patients were recruited to each stage; 19 and 20 had evaluable pharmacokinetics in stages I and II, respectively. Mean (SD) maximum plasma concentrations in stages I and II were 495 (453) and 757 ng/ml (680), respectively; area under the plasma concentration-time curve over 12 h was 4050 (3602) and 6141 ng h/ml (5586), respectively. Statistical/qualitative comparisons showed comparable exposures with adults in stage II; however, the upper 90% confidence interval fell outside the predefined range. Plasma viral load remained undetectable on day 8 in all patients, and etravirine was well tolerated at both doses. CONCLUSION Etravirine 5.2 mg/kg was well tolerated in this study and this dose was selected for further investigation in clinical trials.

A previous study investigating coadministration of etravirine, a nonnucleoside reverse transcriptase inhibitor, and lopinavir/ritonavir soft-gel formulation resulted in nonclinically relevant changes in etravirine and lopinavir exposure. The current study evaluated the pharmacokinetic interaction between etravirine and the lopinavir/ritonavir melt extrusion formulation.Sixteen human immunodeficiency virus (HIV)-negative volunteers were randomized to either treatment sequence A/B or B/A, with 14 days- washout between treatments (treatment A: etravirine 200 mg bid for 8 days; treatment B: lopinavir/ritonavir 400/100 mg bid for 16 days with etravirine 200 mg bid on days 9-16). Steady-state pharmacokinetics were assessed for all antiretrovirals alone and coadministered; pharmacokinetic parameters were obtained by noncompartmental analysis. Safety and tolerability were assessed.Coadministration of etravirine and lopinavir/ritonavir resulted in a 35% decrease in etravirine exposure. Smaller decreases (13%) were observed in lopinavir and ritonavir exposure. Six volunteers reported headache; 1 grade 3 triglyceride increase was reported.Lopinavir/ritonavir induced etravirine metabolism to a similar extent as most other boosted HIV protease inhibitors. The short-term coadministration of etravirine and lopinavir/ritonavir was well tolerated and did not lead to increased incidences of adverse events.

The effects of darunavir-ritonavir at 600 and 100 mg twice daily (b.i.d.) alone, 200 mg of etravirine b.i.d. alone, or 600 and 100 mg of darunavir-ritonavir b.i.d. with 200 mg etravirine b.i.d. at steady state on the steady-state pharmacokinetics of maraviroc, and vice versa, in healthy volunteers were investigated in two phase I, randomized, two-period crossover studies. Safety and tolerability were also assessed. Coadministration of 150 mg maraviroc b.i.d. with darunavir-ritonavir increased the area under the plasma concentration-time curve from 0 to 12 h (AUC 12 ) for maraviroc 4.05-fold relative to 150 mg of maraviroc b.i.d. alone. Coadministration of 300 mg maraviroc b.i.d. with etravirine decreased the maraviroc AUC 12 by 53% relative to 300 mg maraviroc b.i.d. alone. Coadministration of 150 mg maraviroc b.i.d. with etravirine-darunavir-ritonavir increased the maraviroc AUC 12 3.10-fold relative to 150 mg maraviroc b.i.d. alone. Maraviroc did not significantly affect the pharmacokinetics of etravirine, darunavir, or ritonavir. Short-term coadministration of maraviroc with darunavir-ritonavir, etravirine, or both was generally well tolerated, with no safety issues reported in either trial. Maraviroc can be coadministered with darunavir-ritonavir, etravirine, or etravirine-darunavir-ritonavir. Maraviroc should be dosed at 600 mg b.i.d. with etravirine in the absence of a potent inhibitor of cytochrome P450 3A (CYP3A) (i.e., a boosted protease inhibitor) or at 150 mg b.i.d. when coadministered with darunavir-ritonavir with or without etravirine.

The pharmacokinetics and pharmacodynamics of the antiretroviral agent etravirine were evaluated in two phase III clinical trials. Pharmacokinetic data were available in 577 patients randomized to receive etravirine. The mean (SD) population-pharmacokinetics-derived area under the concentration–time curve at 12 h (AUC12 h) and concentration at 0 h (C0 h) were 5,501 (4,544) ng·h/ml and 393 (378) ng/ml, respectively. Hepatitis C coinfection raised etravarine exposure, and concomitant use of tenofovir disoproxil fumarate lowered etravirine exposure, but these changes were not considered clinically relevant. Etravirine apparent oral clearance was not affected by age, weight, sex, race, hepatitis B coinfection status, creatinine clearance, or concomitant use of enfuvirtide. Virologic response (

Despite our progressive understanding of HIV type-1 (HIV-1) infection and the development of a number of antiretroviral agents to delay the onset of AIDS, there remains a need for agents with improved efficacy and safety. In particular, therapy options for treatment-experienced adult patients have been limited by the presence of drug-resistant virus, which often leads to a reduced virological response in these patients. The recently approved non-nucleoside reverse transcriptase inhibitor etravirine has demonstrated durable and superior efficacy over placebo and a favourable tolerability profile in HIV-1-infected, treatment- experienced patients, offering a valuable new therapeutic option. This review examines the clinical development and drug profile of etravirine, placing it in the context of other antiretrovirals available for treatment- experienced patients.

Background A pharmacokinetic trial was conducted to evaluate the potential for once-daily etravirine in anti-retroviral regimens without and with darunavir/ritonavir. Methods During this multicentre, open-label, Phase IIa trial, treatment-naive patients aged ≥18 years with HIV type-1 (HIV-1) received etravirine 400 mg once daily with tenofovir disoproxil fumarate/emtricitabine 300/200 mg once daily from days 1–14; on days 15–28, darunavir/ritonavir 800/100 mg once daily was added. On day 29, etravirine was discontinued and patients continued with the other medications to day 42. Serial blood sampling for etravirine pharmacokinetics was performed over 24 h on day 14 and 28; patients fasted for ≥10 h prior to these visits. Results Of 23 enrolled patients (male 87%, Caucasian 39%), pharmacokinetic profiles for etravirine were available for 21 and 20 patients on day 14 and 28, respectively. The plasma concentration–time profile and pharmacokinetics for etravirine were unchanged with or without darunavir/ritonavir. The mean maximum plasma concentration (Cmax) was reached 4 h after administration and was 790 and 801 ng/ml on day 14 and 28, respectively; mean area under the plasma concentration–time curve (AUC) from before administration to 24 h after administration was 10,410 ng•h/ml on day 14 and 10,720 ng•h/ml on day 28. In a post-hoc analysis, etravirine Cmax was higher, minimum plasma concentration was lower and AUC was similar when compared with etravirine 200 mg twice daily. Conclusions Addition of darunavir/ritonavir to etravirine, all dosed once daily, did not have a clinically significant effect on the pharmacokinetics of etravirine. Findings support further investigation of etravirine 400 mg once daily in HIV-1-infected patients. (Trial registration number NCT00534352.)

Background: Etravirine is a non-nucleoside reverse transcriptase inhibitor (NNRTI) with activity against both wild-type HIV and viruses harboring NNRTI resistance. Etravirine is mainly eliminated via the hepatobiliary route. Objectives: This study in HIV− patients with mild or moderate hepatic impairment and healthy matched controls was conducted to explore the effects of mild and moderate hepatic impairment on the steady-state pharmacokinetics of etravirine and to provide guidance for the treatment of HIV+ patients with hepatic impairment. Methods: This open-label, multiple-dose study enrolled HIV− patients aged 18 to 65 years with mild or moderate hepatic impairment (Child-Pugh score, 5–6 or 7–9, respectively) and healthy volunteers matched for age, sex, race, and body mass index (BMI). All subjects received etravirine 200 mg BID with food for 7 days and a morning dose on day 8. Etravirine pharmacokinetics over a period of 12 hours on days 1 and 8 were determined using noncompartmental methods and analyzed using linear mixed-effects modeling. Tolerability of etravirine was assessed based on the reported adverse events, laboratory investigations, ECG, and physical examination. Results: Each group comprised 8 subjects (mild hepatic impairment patients: 5 men, 3 women; median age, 57 years [range, 41–65 years]; BMI, 26 kg/m 2 [range, 20–32 kg/m 2 ]; moderate hepatic impairment patients: 6 men, 2 women; age, 54 years [range, 44–64 years]; BMI, 26 kg/m 2 [range, 22–32 kg/m 2 ]). All patients were white and light smokers. On day 8, the least squares mean ratios (90% CIs) of the logtransformed pharmacokinetic properties in patients with mild and moderate hepatic impairment were, respectively: C min , 0.87 (0.65–1.17) and 0.98 (0.68–1.42) μg/mL; C max , 0.79 (0.63–1.00) and 0.72 (0.54–0.96) ug/mL; and AUC 0–12 , 0.87 (0.69–1.09) and 0.82 (0.60–1.11) μg/mL/h. All treatment-emergent adverse events were considered mild to moderate; the most common were headache (50% in healthy controls) and fatigue and nausea (both 25% in patients with mild hepatic impairment). No clinically significant changes in laboratory parameters, physical examination including vital signs, or ECG were observed. One serious adverse event was reported during the follow-up period in a patient with moderate hepatic impairment due to hepatic cirrhosis secondary to alcoholism. This patient presented at screening with dilated cardiomyopathy and cardiac arrhythmia. Conclusions: In this Phase I pharmacokinetic study, no clinically relevant differences were observed between patients with mild or moderate hepatic impairment and healthy matched subjects with regard to the pharmacokinetics of etravirine. Based on these findings in these HIV− volunteers, no dose adjustment of etravirine appears to be necessary in patients with mild or moderate hepatic impairment. Etravirine was generally well tolerated.

Current HIV treatment guidelines emphasize the importance of using an active antiretroviral therapy regimen that produces full virologic suppression and immunologic competence, while at the same time providing patients with a favorable safety profile and limited risk for development of drug resistance. Etravirine (TMC125), a recently approved, non-nucleoside reverse transcriptase inhibitor (NNRTI), has shown durable, superior virologic efficacy over placebo in the Phase III, randomized, double-blind DUET trials in 1,203 treatment-experienced, NNRTI-resistant, HIV-1-infected patients. Statistical significance of responses with etravirine over placebo was maintained through Week 24, 48 and 96, regardless of baseline demographics, baseline disease characteristics or the background regimen used. Etravirine has demonstrated a favorable safety and tolerability profile; the incidence of treatment-emergent adverse events was comparable with placebo in the DUET trials, with the exception of rash. The tolerability profile of etravirine also appears to be favorable in terms of neuropsychiatric and hepatic side effects. The pharmacokinetic profile of twice-daily etravirine minimizes the potential for clinically relevant drug-drug interactions and allows for its use in combination with a wide range of other agents. In addition, etravirine has a high genetic barrier to the development of resistance, further enhancing potential benefit in patients infected with NNRTI-resistant virus. The clinical efficacy and favorable safety profile of etravirine, together with its pharmacokinetic profile and high genetic barrier to resistance, make it a valuable treatment option for a wide range of treatment-experienced HIV-1-infected patients.

Objective Two open-label, randomized, cross-over trials in healthy volunteers were conducted to investigate the pharmacokinetic interaction between etravirine and tenofovir disoproxil fumarate. Methods Etravirine was administered as either 800 mg twice a day (bid) (phase II formulation in Study 1) or 200 mg bid (phase III formulation in Study 2) for 8 days followed by a 12 h pharmacokinetic evaluation. After a minimum of 14 days washout, tenofovir disoproxil fumarate 300 mg once a day was administered for 16 days. Volunteers were randomized to receive co-administration of etravirine with tenofovir disoproxil fumarate on either days 1–8 or days 9–16 followed by a 12 h pharmacokinetic evaluation for etravirine on day 8 or 16, respectively. Plasma and urine tenofovir concentrations were determined on days 8 and 16 over 24 h. Results The least square mean (LSM) ratio [90% confidence interval (CI)] for the area under the plasma concentration–time curve from 0 to 12 h (AUC12 h) for etravirine co-administered with tenofovir disoproxil fumarate vs. etravirine alone was 0.69 (0.61–0.79) and 0.81 (0.75–0.88) in Studies 1 and 2, respectively. The LSM ratio (90% CI) for the effect of etravirine on tenofovir AUC24 h was 1.16 (1.09–1.23) in Study 1 and 1.15 (1.09–1.21) in Study 2. Conclusions These alterations are not considered clinically relevant for either drug and no dose adjustment is necessary when etravirine and tenofovir disoproxil fumarate are co-administered.