Discontinuation Rates for Protease Inhibitor Regimens Containing Ritonavir 600 mg versus Ritonavir 400 mg Plus Saquinavir 400 mg

Abstract

OBJECTIVE: A retrospective study was performed to determine whether twice-daily ritonavir 400 mg plus twice-daily saquinavir 400 mg (ritonavir 400/saquinavir 400) was better tolerated than ritonavir 600 mg twice daily (ritonavir 600). A secondary objective was to determine whether the rate of discontinuation due to therapeutic failure differed between the two ritonavir regimens. DESIGN: The study was a retrospective chart review. Data collected included ritonavir dose; length of ritonavir therapy; reason for discontinuation; HIV-1 RNA prior to and at discontinuation of ritonavir therapy; CD4+ count; and antiretroviral therapy prior to, concomitant with, and initiated after ritonavir therapy. SETTING: Patient charts were reviewed in a university teaching hospital clinic. PATIENTS: Patients were identified through a search of the pharmacy database from December 18, 1995, to December 18, 1997. Patients were >18 years old, but not restricted by gender or race. MAIN OUTCOME MEASURES: The main outcome measures were frequency of discontinuation of ritonavir due to intolerance or due to lack of therapeutic efficacy. RESULTS: The search identified 116 patients, including 57 patients taking ritonavir 400/saquinavir 400 and 54 patients taking ritonavir 600. Five patients on other ritonavir regimens were excluded. Significantly fewer patients receiving ritonavir 400/saquinavir 400 (14%) discontinued ritonavir due to intolerance compared with ritonavir 600 (37%; p = 0.002). Discontinuations due to therapeutic failure were not significantly different: 8.8% for ritonavir 400/saquinavir 400 and 7.4% for ritonavir 600, despite the fact that ritonavir/saquinavir therapy followed another protease inhibitor in 41 patients (73.2%) compared with 12 patients (24.5%) for ritonavir 600 (p = 0.001). CONCLUSIONS: Ritonavir 400/saquinavir 400 is better tolerated than ritonavir 600.