The protease inhibitor indinavir (Crixivan) is not recommended for use in pregnant women with HIV, according to a revision of the United States Food and Drug Administration’s (FDA’s) drug information.
The FDA’s update was made last month after inclusion of the results of the PACTG 358 study. “Results from this study show substantially reduced indinavir concentrations in women at 30 – 32 weeks gestation compared to postpartum,” states the warning. “Based on these data, the Precautions Section now states that indinavir is not recommended in HIV-infected pregnant patients.”
It is feared that low levels of indinavir may lead to the development of resistance and treatment failure. This may increase the chances of the mother passing on HIV to her baby during delivery, as well as limiting future treatment options for both mother and child.
PACTG 358 studied the blood concentration of indinavir in eleven pregnant HIV-infected patients taking 800mg indinavir and 200mg AZT (zidovudine, Retrovir) three times a day and 150mg 3TC (lamivudine, Epivir) twice daily. All the patients were between 14 and 28 weeks pregnant at the start of the study.
At weeks 30 to 32 of gestation, the mean total indinavir exposure in the first eight hours after dosing was 9230nM.h. This was 74% below the value measured at six weeks after giving birth (95% confidence interval: 50, 86%).
In addition, eight hours after the indinavir dose, the mean concentration of the drug (Cmin) was below the minimum level that could be measured in six (55%) of the patients.
Crixivan is manufactured by Merck Sharpe & Dohme, and was approved for use in Europe in October 1996. Generic versions of indinavir are also manufactured by companies in India, although these have not yet been prequalified by the World Health Organization.