title: A review of low-dose ritonavir in protease inhibitor combination therapy.
abstract: The pharmacokinetics of protease inhibitors center around the microsomal enzyme cytochrome P-450 3A4. As a potent inhibitor of this enzyme, ritonavir can increase the bioavailability and half-life of coadministered protease inhibitors. Evidence suggests that increased exposure to protease inhibitors is clinically relevant. Antiretroviral treatment with low-dose ritonavir-boosted lopinavir, indinavir, and saquinavir has durable virological activity and shows impressive immune reconstitution. Although tolerable in most cases, gastrointestinal side effects, hepatotoxicity, and blood lipid abnormalities remain relevant issues. Additional study will elucidate the advantages and disadvantages of twice-daily, low-dose ritonavir-boosted regimens and determine whether once-daily regimens based on this principle will have a lasting role in clinical practice.
authors.affiliation: Division of Infectious Diseases, The Ottawa Hospital-General Campus, Ottawa, ON, Canada K1H 8L6. ccooper@ottawahospital.on.ca
authors.forename: C L
authors.initials: CL
authors.lastname: Cooper
authors.forename: R P G
authors.initials: RP
authors.lastname: van Heeswijk
authors.forename: K
authors.initials: K
authors.lastname: Gallicano
authors.forename: D W
authors.initials: DW
authors.lastname: Cameron
mesh_terms: D023241:Antiretroviral Therapy, Highly Active; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000187:drug effects / Q000378:metabolism; D024882:Drug Resistance, Viral; D004359:Drug Therapy, Combination; D015658:HIV Infections / Q000188:drug therapy*; D017320:HIV Protease Inhibitors / Q000008:administration & dosage / Q000627:therapeutic use*; D006801:Humans; D019469:Indinavir / Q000627:therapeutic use; D019438:Ritonavir / Q000008:administration & dosage / Q000627:therapeutic use*; D019258:Saquinavir / Q000008:administration & dosage / Q000627:therapeutic use
chemical_list: D017320:HIV Protease Inhibitors; D019469:Indinavir; D003577:Cytochrome P-450 Enzyme System; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A; D019258:Saquinavir; D019438:Ritonavir