Comparison of two indinavir/ritonavir regimens in the treatment of HIV-infected individuals.

Author(s): Acosta EP, Wu H, Hammer SM, Yu S, Kuritzkes DR, Walawander A, Eron JJ, Fichtenbaum CJ, Pettinelli C, Neath D, Ferguson E, Saah AJ, Gerber JG, Adult AIDS Clinical Trials Group 5055 Protocol Team

Affiliation(s): Division of Clinical Pharmacology, University of Alabama at Birmingham School of Medicine, Birmingham, AL 35294-0019, USA. EAcosta@uab.edu

Publication date & source: 2004-11-01, J Acquir Immune Defic Syndr., 37(3):1358-66.

Publication type: Clinical Trial; Controlled Clinical Trial; Randomized Controlled Trial

BACKGROUND: Pharmacokinetic enhancement of protease inhibitors (PIs) with low-dose ritonavir (RTV) for salvage therapy is increasingly common. The purpose of this study was to compare the pharmacokinetics, safety, and tolerability of indinavir (IDV)/RTV at 800/200 mg (arm A) and 400/400 mg (arm B) administered twice daily in HIV-infected subjects failing their first PI-based regimen. METHODS: A phase I/II, randomized, open-label, 24-week study was conducted. Formal 12-hour pharmacokinetic evaluations were performed, and study visits occurred at baseline; at weeks 1, 2, and 4; and every 4 week thereafter for 24 weeks. Clinical symptoms and laboratory assessments were collected. Subjects were allowed to switch arms because of toxicity. RESULTS: Forty-four subjects were enrolled (22 per arm). IDV predose concentration, maximum plasma concentration and area under the curve were significantly higher in arm A. Fifty-five percent and 45% of subjects in arms A and B responded (<200 copies/mL at week 24; P = 0.76), respectively. CD4 cell responses were similar. All subjects had IDV-sensitive virus at baseline and at virologic failure. Tolerability was comparable, but all grade 3 or higher triglyceride increases occurred in arm B and more subjects in arm B switched because of toxicity (5 vs. 1 triglyceride increases). CONCLUSIONS: This is the largest formal pharmacokinetic evaluation of 2 dosage combinations of IDV/RTV in HIV-infected individuals. Pharmacokinetic parameters were consistent with previous results in patients but lower than in seronegative controls. Both regimens exhibited similar tolerability and response rates. High toxicity with a low response suggests that the optimum IDV/RTV combination would include an RTV dose <400 mg and an IDV dose <800 mg in this population.