title: A preliminary study of ritonavir, an inhibitor of HIV-1 protease, to treat HIV-1 infection.
abstract: BACKGROUND
  Ritonavir is a potent inhibitor in vitro of human immunodeficiency virus type 1 (HIV-1) protease, which is needed for virions to mature and become infective. We assessed the safety and efficacy of ritonavir in patients with HIV-1 infection.
  
  
  METHODS
  We administered ritonavir orally to 62 patients in one of four dosages during a 12-week trial containing a 4-week randomized, placebo-controlled, double-blinded phase followed by an 8-week dose-blinded phase. We assessed the response with serial measurements of plasma viremia and serial CD4 cell counts.
  
  
  RESULTS
  Fifty-two patients completed the 12-week trial. Diarrhea and nausea were the most common side effects, and reversible elevations in serum triglyceride and gamma-glutamyltransferase levels were the most frequent laboratory abnormalities. Ritonavir had a rapid antiviral effect, with a mean maximal reduction in the number of copies of HIV-1 RNA per milliliter of plasma that ranged from 0.86 to 1.18 log in the four dosage groups. After 12 weeks of treatment, the antiviral effect was partially maintained, with a mean reduction in plasma viremia of 0.5 log. When we used a more sensitive assay for HIV-1 RNA in a subgroup of 20 patients, we found that plasma viremia decreased by a mean of 1.7 log. This antiviral effect was partly sustained at week 12, with a mean reduction of approximately 1.1 log. The patients' CD4 cell counts rose during treatment with ritonavir (median increase, 74 and 83 cells per cubic millimeter at weeks 4 and 12, respectively).
  
  
  CONCLUSIONS
  The protease inhibitor ritonavir is well tolerated and has a potent antiviral effect, as shown by substantial decreases in plasma viremia and significant elevations in CD4 cell counts. Expanded clinical trials of ritonavir are warranted.
mesh_terms: D000328:Adult; D000998:Antiviral Agents / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D018791:CD4 Lymphocyte Count / Q000187:drug effects; D004311:Double-Blind Method; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000276:immunology; D017320:HIV Protease Inhibitors / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D015497:HIV-1 / Q000187:drug effects*; D006801:Humans; D008297:Male; D012367:RNA, Viral / Q000097:blood; D019438:Ritonavir; D013844:Thiazoles / Q000627:therapeutic use*; D016896:Treatment Outcome; D014633:Valine / Q000031:analogs & derivatives* / Q000627:therapeutic use
chemical_list: D000998:Antiviral Agents; D017320:HIV Protease Inhibitors; D012367:RNA, Viral; D013844:Thiazoles; D014633:Valine; D019438:Ritonavir