Microboosting of Atazanavir 300 mg With 50 mg Versus 100mg Ritonavir Daily in HIV-infected Patients: a Pharmacokinetic Study

This is an open-label, single group study to determine the pharmacokinetic profile of atazanavir 300 mg daily boosted with ritonavir 100mg daily in HIV-infected patients over a period of 9 days. Ritonavir and atazanavir are protease inhibitors used to treat HIV. However, ritonavir, when used at low doses (up to 100mg) does not have HIV activity, but will enhance (boost) the blood concentrations of other drugs like atazanavir. Recently, a study showed that taking 50mg of ritonavir administered in an oral solution led to similar blood concentrations of atazanavir than when given with 100mg of ritonavir. Potential benefits associated with a lower dose of ritonavir may include a reduction of side effects such as upset stomach and an improvement in cholesterol level. This study will look at the amount of atazanavir into your blood when given with ritonavir in a tablet formulation at 50mg or 100mg with standard atazanavir dose (300mg).