Drug Interaction Report

According to the product labeling, clinically significant interactions are not expected between atazanavir and substrates of CYP450 1A2, 2A6, 2B6, 2C19, 2C9, 2D6, or 2E1. No particular precaution or dosage adjustment should be necessary.

CONTRAINDICATED: Consumption of ethanol during treatment with disulfiram may cause flushing, nausea, blurred vision, dyspnea, tachypnea, tachycardia, and hypotension. Death has been reported. The mechanism is probably related to inhibition of aldehyde dehydrogenase, the enzyme responsible for the oxidation of acetaldehyde to acetyl CoA. Accumulation of acetaldehyde probably results.

MANAGEMENT: Ethanol should be avoided in patients receiving disulfiram.

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.