• Preliminary Results from Indinavir (IDV) and Ritonavir (RTV) in a Once-Daily Regimen (Marck 103/104) (Poster 336)
  Authored by J. Suleiman, R. Rhodes, R. Campo, P. Piliero, R. Steigbigel, J. Chen, G. Winchell, and A. Saah
  View the original abstract

In another study of the indinavir/ritonavir combination, a once-daily regimen of 1,200mg indinavir and 200mg ritonavir was examined in antiretroviral therapy-naive patients. They were also given d4T and 3TC at standard doses, which meant that they were taking their nucleoside analogues twice daily. The study was conducted in Brazil and the United States.

There were forty participants, with a median baseline viral load of 4.91 log (just under 100,000 copies/mL) and median CD4 cell count of 329. Eight patients during the course of the study discontinued treatment. At the end of 24 weeks, 87% of those remaining on study had viral loads <400 copies/mL, 66% <50 copies/mL; by the more rigorous intention to treat analysis, these numbers were 72% and 54%, respectively. There were six patients who had drug-related adverse effects, including hair loss (five occurrences), nausea (two), and kidney stones (one). None of the side effects prompted study discontinuation. Pharmacokinetic analysis of nine patients was reassuring, in that the trough level of indinavir exceeded the IC95 for wild-type virus in each individual studied. Fasting lipid analysis showed a slight but significant rise in both total cholesterol and triglycerides.

These preliminary results support the further study of once-daily indinavir/ritonavir, and indeed Merck is planning on both continuing the present cohort as well as looking at a 1,200mg indinavir/400mg ritonavir dose. However, as with any 24-week result, the findings should be viewed as only tentative regarding both efficacy and safety until further data are presented. Consequently, in choosing an indinavir/ritonavir dosing combination, for now the twice-daily regimens listed above are preferred.