The effect of single- and multiple-dose etravirine on a drug cocktail of representative cytochrome P450 probes and digoxin in healthy subjects.

The effect of etravirine on cytochrome P450 (CYP) enzymes and P-glycoprotein were evaluated in two randomized, crossover trials in healthy subjects. A modified Cooperstown 5 + 1 cocktail was utilized to determine the effects of etravirine on single-dose pharmacokinetics of model CYP probes. The cocktail was administered alone, then, after a 14-day washout, etravirine 200 mg twice daily (bid) was given for 14 days with cocktail on days 1 and 14. In a separate study, digoxin (0.5 mg) was administered alone, then, after a 14-day washout, etravirine 200 mg bid was administered for 12 days with digoxin on day 8. In the cocktail study, the AUClast least squares mean (LSM) ratios (90% confidence intervals [CIs]) for cocktail + etravirine versus cocktail were 0.93 (0.88, 0.99; paraxanthine), 0.58 (0.44, 0.75; 7-OH-S-warfarin), 0.43 (0.20, 0.96; 5-OH-omeprazole), 0.85 (0.78, 0.94; dextrorphan), and 0.69 (0.64, 0.74; midazolam). Digoxin AUC0-8h was slightly increased with etravirine coadministration (LSM ratio 1.18 [0.90, 1.56]). These data suggest that etravirine is a weak CYP3A isozyme inducer and minimally inhibits CYP2C9, 2C19, and P-glycoprotein activity.

Pharmacokinetics of darunavir after administration of an oral suspension with low-dose ritonavir and with or without food.

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.

Pharmacokinetics of multiple-dose darunavir in combination with low-dose ritonavir in individuals with mild-to-moderate hepatic impairment.

BACKGROUND AND OBJECTIVE: The pharmacokinetics of some HIV protease inhibitors are altered in patients with hepatic impairment. The TMC114-C134 study assessed the pharmacokinetics and safety of darunavir/ritonavir 600 mg/100 mg twice daily in HIV-negative subjects with hepatic impairment (defined according to Child-Pugh classification A [mild] or B [moderate]) compared with matched, HIV-negative, healthy subjects. METHODS: All subjects received darunavir/ritonavir 600 mg/100 mg twice daily for 6 days with a morning dose on day 7. Pharmacokinetic profiles were obtained up to 72 hours post-dose for darunavir and 12 hours post-dose for ritonavir on day 7. Safety and tolerability were also assessed. RESULTS: Darunavir pharmacokinetics in subjects with mild (n = 8) and moderate (n = 8) hepatic impairment were comparable to those in matched healthy control subjects (n = 16). In those with mild hepatic impairment, the least square mean ratios relative to healthy subjects for darunavir exposure (the area under the plasma concentration-time curve from 0 to 12 hours) and for maximum and minimum plasma concentrations were 0.94 (90% CI 0.75, 1.17), 0.88 (90% CI 0.73, 1.07) and 0.83 (90% CI 0.63, 1.10), respectively. In those with moderate hepatic impairment, these values were 1.20 (90% CI 0.90, 1.60), 1.22 (90% CI 0.95, 1.56) and 1.27 (90% CI 0.87, 1.85), respectively. Ritonavir pharmacokinetics were comparable between healthy subjects and those with mild hepatic impairment, but mean exposure was 50% higher in subjects with moderate hepatic impairment. Darunavir/ritonavir was generally well tolerated, regardless of hepatic impairment. All adverse events were grade 1-2 in severity, except for a grade 3 increase in alanine aminotransferase reported in one subject with mild hepatic impairment. No adverse events led to discontinuation. CONCLUSIONS: The results of this study show that the pharmacokinetics of darunavir/ritonavir 600 mg/100 mg are not affected by mild or moderate hepatic impairment. Therefore, it is recommended that dose adjustments of darunavir/ritonavir are not required in patients with mild or moderate hepatic impairment.

Pharmacokinetic and pharmacodynamic study of the concomitant administration of methadone and TMC125 in HIV-negative volunteers.

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 AUC(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.