Low plasma concentrations of indinavir are related to virological treatment failure in HIV-1-infected patients on indinavir-containing triple therapy

All human immunodeficiency virus type 1 (HIV-1)-infected patients who start ed to use indinavir (800 mg three times a day) as part of their triple drug regimen were included in a study to determine the importance of low plasma concentrations of indinavir as a cause of virological treatment failure. T he indinavir concentration and a number of patient characteristics at basel ine were tested as risk factors for virological treatment failure (defined as a viral load above 200 copies/ml after 24 weeks of treatment) in univari ate and multivariate analyses; 65 patients were included. Virological treat ment failure occurred in 36.9% of the patients. Multivariate analysis showe d that a low plasma concentration of indinavir (odds ratio 0.1), a high vir al load at baseline (odds ratio 2.6) and pretreatment with another protease inhibitor (odds ratio 10.0) were independent factors related to virologica l treatment failure. Monitoring of indinavir plasma concentrations may be a n important tool for the optimization of triple drug combination therapy.