Ritonavir.
Ritonavir is a protease inhibitor with an HIV-1 resistance profile similar to that of indinavir, but different from that of saquinavir. Ritonavir has good oral bioavailability, and may increase the bioavailability of other protease inhibitors including saquinavir, nelfinavir, indinavir and VX-478. Clinically significant drug interactions have been predicted between ritonavir and a range of medications. In patients with HIV-1 infection, ritonavir markedly reduced viral load within 2 weeks of treatment onset and also increased CD4+ cell counts. In a large placebo-controlled trial in patients with advanced HIV infection, the addition of ritonavir to existing therapy reduced the risk of mortality by 43% and clinical progression by 56% after 6.1 months. Triple therapy with ritonavir plus zidovudine, in combination with lamivudine or zalcitabine, reduced HIV viraemia to below detectable levels in most patients with acute, and some patients with advanced HIV infection in 2 small trials. Early results suggest combination therapy with ritonavir and saquinavir increases CD4+ cell counts and decreases HIV RNA levels in patients with previously untreated HIV infection.
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Adis International Limited, Auckland, New Zealand.
Faulds
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D000284:Administration, Oral; D019380:Anti-HIV Agents / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000627:therapeutic use; D001682:Biological Availability; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000187:drug effects*; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D004361:Drug Tolerance; D015658:HIV Infections / Q000188:drug therapy* / Q000235:genetics / Q000401:mortality; D017320:HIV Protease Inhibitors / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D019259:Lamivudine / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D007958:Leukocyte Count / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D016032:Randomized Controlled Trials as Topic; D019438:Ritonavir / Q000378:metabolism / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000627:therapeutic use; D016047:Zalcitabine / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D015215:Zidovudine / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use
D019380:Anti-HIV Agents; D017320:HIV Protease Inhibitors; D012333:RNA, Messenger; D019259:Lamivudine; D015215:Zidovudine; D016047:Zalcitabine; D003577:Cytochrome P-450 Enzyme System; D019438:Ritonavir