title: Pharmacokinetic interaction between rifampin and the combination of indinavir and low-dose ritonavir in HIV-infected patients.
abstract: Rifampin is an important drug in the treatment of tuberculosis, but administration of rifampin in combination with protease inhibitors is complicated because of drug-drug interactions. A prospective, controlled, multiple-dose study involving 6 HIV-infected patients receiving a combination of indinavir (800 mg) and ritonavir (100 mg) twice a day was performed to evaluate whether the inducing effect of rifampin on the drug-metabolizing enzyme cytochrome P450 (CYP) 3A4 could be overcome by the inhibitory effect of ritonavir. Pharmacokinetic evaluations of steady-state concentrations of indinavir and ritonavir were performed before and after administration of rifampin (300 mg every day for 4 days). An 87% reduction (from 837 to 112 ng/mL) in median indinavir and a 94% reduction (from 431 to 27 ng/mL) in median ritonavir concentrations were seen 12 h after the last dose of rifampin was administered (P=.031). These results strongly indicate that the administration of rifampin with a combination of indinavir (800 mg) and ritonavir (100 mg) could lead to subtherapeutic concentrations of indinavir.
authors.affiliation: Institute of Public Health, Clinical Pharmacology, University of Southern Denmark, Odense. ujustesen@health.sdu.dk
authors.forename: U S
authors.initials: US
authors.lastname: Justesen
authors.forename: A B
authors.initials: AB
authors.lastname: Andersen
authors.forename: N A
authors.initials: NA
authors.lastname: Klitgaard
authors.forename: K
authors.initials: K
authors.lastname: Brøsen
authors.forename: J
authors.initials: J
authors.lastname: Gerstoft
authors.forename: C
authors.initials: C
authors.lastname: Pedersen
mesh_terms: D000328:Adult; D000995:Antitubercular Agents / Q000493:pharmacokinetics*; D004347:Drug Interactions; D015658:HIV Infections / Q000378:metabolism*; D017320:HIV Protease Inhibitors / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006801:Humans; D019469:Indinavir / Q000493:pharmacokinetics; D008875:Middle Aged; D011446:Prospective Studies; D012293:Rifampin / Q000493:pharmacokinetics*; D019438:Ritonavir / Q000008:administration & dosage / Q000493:pharmacokinetics
chemical_list: D000995:Antitubercular Agents; D017320:HIV Protease Inhibitors; D019469:Indinavir; D019438:Ritonavir; D012293:Rifampin