A pilot trial of indinavir, ritonavir, didanosine, and lamivudine in a once-daily four-drug regimen for HIV infection.
OBJECTIVE
To evaluate the tolerance, pharmacokinetics, and virologic and immunologic outcomes of once-daily indinavir, ritonavir, didanosine, and lamivudine in HIV-seropositive individuals.


METHODS
Open-label 24-week pilot study.


METHODS
Ten HIV-seropositive subjects who were either antiretroviral-naive or minimally experienced with short-term single-or dual-nucleoside therapy provided informed consent and were enrolled. All subjects received didanosine (400 mg) 30 to 60 minutes before a meal followed by indinavir (1200 mg), ritonavir (400 mg), and lamivudine (300 mg) concurrent with the aforementioned meal.


METHODS
Safety laboratory tests, including a complete blood cell count and amylase, lipase, liver transaminase, and nonfasting lipid monitoring as well as plasma HIV viral load and CD4+ lymphocyte count, were carried out at monthly intervals. Genotyping was performed at baseline. Pharmacokinetic studies for indinavir and ritonavir were performed at week 8.


RESULTS
Nine of 10 subjects completed 24 weeks of therapy. No subject demonstrated primary protease inhibitor mutations at baseline. Toxicities experienced by subjects were typically mild and consistent with those commonly reported for each of the medications, including two cases of hematuria. By week 24, median nonfasting cholesterol and triglyceride levels increased by 49% and 108%, respectively. Median baseline plasma HIV viral load and CD4+ lymphocyte count were 29,292 (4.47 log10) copies/ml and 224 cells/mm3, respectively. Eight of 10 subjects had a plasma HIV viral load of <50 copies/ml by week 12. The 2 subjects with a detectable HIV viral load reached <50 copies/ml by week 28. Median CD4+ lymphocyte counts increased by 193 cells/mm3 at week 24. Indinavir and ritonavir plasma concentrations remained above respective inhibitory and effective concentrations (IC95 and EC50) (uncorrected for protein binding) throughout the 24-hour dosing interval for 6 of 10 and 8 of 10 subjects, respectively.


CONCLUSIONS
Our pilot study demonstrates excellent virologic suppression despite low minimum protease inhibitor concentrations during a dosing interval in some patients and is supportive of further study.
Mole
L
L
Veterans Affairs Palo Alto Health Care System, Palo Alto, California 94304, USA. larry.mole@med.va.gov
Schmidgall
D
D
Holodniy
M
M
D000328:Adult; D019380:Anti-HIV Agents / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D018791:CD4 Lymphocyte Count; D002784:Cholesterol / Q000097:blood; D016049:Didanosine / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use; D004341:Drug Evaluation; D004359:Drug Therapy, Combination; D005838:Genotype; D015658:HIV Infections / Q000188:drug therapy* / Q000276:immunology / Q000821:virology; D017320:HIV Protease Inhibitors / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D006801:Humans; D019469:Indinavir / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use; D019259:Lamivudine / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D019438:Ritonavir / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use; D012449:Safety; D016896:Treatment Outcome; D014280:Triglycerides / Q000097:blood; D019562:Viral Load
D019380:Anti-HIV Agents; D017320:HIV Protease Inhibitors; D014280:Triglycerides; D019259:Lamivudine; D019469:Indinavir; D002784:Cholesterol; D016049:Didanosine; D019438:Ritonavir