Drug Interaction Report

ADJUST DOSING INTERVAL: Concurrent administration of antacids or other agents with acid-neutralizing effects may decrease the oral bioavailability of atazanavir and substantially reduce its concentrations in plasma. Atazanavir solubility decreases with increasing pH, thus reduction in gastric acidity may interfere with dissolution of the drug. Subtherapeutic antiretroviral drug levels may lead to reduced viral susceptibility and development of resistance.

MANAGEMENT: Atazanavir should be administered 2 hours before or 1 hour after antacids or other oral agents with acid-neutralizing effects.

ADJUST DOSING INTERVAL: Administration of atazanavir with food enhances oral bioavailability and reduces pharmacokinetic variability. According to the manufacturer, administration with a light meal increased the peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of a single 400 mg dose of atazanavir by 57% and 70%, respectively, relative to the fasting state. Administration with a high-fat meal resulted in a mean increase of 35% in atazanavir AUC and no change in Cmax compared to fasting. The coefficient of variation of AUC and Cmax decreased by approximately one-half when given with either a light or high-fat meal compared to the fasting state.

MANAGEMENT: To ensure maximal oral absorption, atazanavir should be administered with or immediately after a meal.