The effects of ritonavir and lopinavir/ritonavir on the pharmacokinetics of a novel CCR5 antagonist, aplaviroc, in healthy subjects.

ABSTRACT

AIMS: This study assessed the effects of the CYP3A inhibitors lopinavir/ritonavir (LPV/r) on the steady-state pharmacokinetics (PK) of aplaviroc (APL), a CYP3A4 substrate, in healthy subjects. METHODS: In Part 1, APL PK was determined in eight subjects who received a single oral 50-mg APL test dose with/without a single dose of 100 mg ritonavir (RTV). Part 2 was conducted as an open-label, single-sequence, three-period repeat dose study in a cohort of 24 subjects. Subjects received APL 400 mg every 12 h (b.i.d.) for 7 days (Period 1), LPV/r 400/100 mg b.i.d. for 14 days (Period 2) and APL 400 mg + LPV/r 400/100 mg b.i.d. for 7 days (Period 3). All doses were administered with a moderate fat meal. PK sampling occurred on day 7 of Periods 1 and 3 and day 14 of Period 2. RESULTS: In Part 1, a single RTV dose increased the APL AUC(0-infinity) by 2.1-fold [90% confidence interval (CI) 1.9, 2.4]. Repeat dose coadministration of APL with LPV/r increased APL exposures to a greater extent with the geometric least squares mean ratios (90% CI) being 7.7 (6.4, 9.3), 6.2 (4.8, 8.1) and 7.1 (5.6, 9.0) for the APL AUC, C(max), and C(min), respectively. No change in LPV AUC or C(max) and a small increase in RTV AUC and C(max) (28% and 32%) were observed. The combination of APL and LPV/r was well tolerated and adverse events were mild in severity with self-limiting gastrointestinal complaints most commonly reported. CONCLUSIONS: Coadministration of APL and LPV/r was well tolerated and resulted in significantly increased APL plasma concentrations.