Brecanavir interaction study with ritonavir and atazanavir

Brecanavir is a new protease inhibitor that is currently in clinical studies and it is being studied in combination with low dose ritonavir. A drug interaction study involving 48 HIV-negative individuals participated in this study to evaluate the effects of atazanavir and ritonavir on brecanavir drug levels.

The results from the study showed that the addition of atazanavir (300mg once a day) to brecanavir/ritonavir (300mg/100mg every 12 hours) led to higher brecanavir, ritonavir and atazanavir drug levels. AUC levels of all drugs increased: brecanavir by an average of 38%, ritonavir by 56% and atazanavir levels by 44%. Results from this study suggest that atazanavir further increases brecanavir levels on top of the increase already seen with low dose ritonavir and a reduction in the dose of atazanavir should be considered.

Ford S, Murray S, Anderson M et al. Brecanavir/ritonavir and atazanavir/ritonavir increased following repeat co-administration. 7th International Workshop on Clinical Pharmacology of HIV Therapy, 20-22 April 2006, Lisbon. Abstract 76.