Saquinavir (Invirase) Useful in HIV Patients with Gastrointestinal Problems

By David Douglas

Despite its low bioavailability, the protease inhibitor saquinavir (Invirase) still appears to be helpful in HIV-infected patients with diarrhea and wasting syndrome, French researchers report in the February issue of Antimicrobial Agents and Chemotherapy.

As lead investigator Dr. Herve Trout told Reuters Health, "diarrhea is not a major obstacle to treatment of HIV-1-infected patients, even with low intrinsic bioavailability drugs."

Dr. Herve Trout of Hopital Lariboisiere, Paris, and colleagues note that antiretroviral-naive patients with these symptoms "still exist today, particularly in Africa and Asia."

To gain further information on the bioavailability of saquinavir in such situations, the researchers conducted an open-label study in 100 HIV patients. Patients were classified as being asymptomatic, AIDS symptomatic without weight loss or diarrhea, and AIDS symptomatic with weight loss and diarrhea.

All received a single daily 600 mg oral dose of saquinavir in a hard gelatin capsule. This was given along with a standard breakfast, which included 200 mL of grapefruit juice.

The researchers note that at the end of the 1990s, when the study started, "it was usual practice to co-administer grapefruit juice in order to increase saquinavir absorption."

Blood samples showed that measures of drug exposure were significantly greater in the group with diarrhea and wasting. In particular, the median AUC amounted to 705 ng per hour per mL in this group. The corresponding value in the group with no diarrhea and wasting was 349 ng per hour per mL. In patients with no symptoms, the figure was 165 ng per hour per mL.

The increased exposure, say the researchers, could be due to "a paracellular crossing of saquinavir as the illness spreads." It correlated mainly with a decrease in intestinal absorption and a relative increase in dose as body weight fell.

Given these findings, Dr. Trout concluded, "Saquinavir can be used to treat patients with diarrhea and/or wasting syndrome." However, he added, in treating such patients, "therapeutic drug monitoring should be established to determine the right dose to give."

03/03/04

Antimicrob Agents Chemother 2004;48:538-545.