Drug Interaction Report

GENERALLY AVOID: Sorbitol may decrease the serum concentration of lamivudine. The mechanism of interaction has not been established. In an open-label, randomized sequence, 4-period, crossover study of 16 healthy adult subjects, a single 300 mg dose of lamivudine oral solution was administered alone or in combination with a single 3.2 g, 10.2 g, or 13.4 g dose of sorbitol oral solution. Coadministration of lamivudine with sorbitol resulted in dose-dependent decreases in lamivudine AUC (14%, 32%, and 36%) and Cmax (28%, 52%, and 55%).

MANAGEMENT: When possible, avoid use of lamivudine with products that contain osmotic polyalcohols (e.g., sorbitol) or monosaccharide alcohols (e.g., lactitol, mannitol). If coadministration cannot be avoided, more frequent monitoring of viral load should be considered.

Food enhances the oral absorption and bioavailability of tenofovir, the active entity of tenofovir disoproxil fumarate. According to the product labeling, administration of the drug following a high-fat meal increased the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of tenofovir by approximately 14% and 40%, respectively, compared to administration in the fasting state. However, administration with a light meal did not significantly affect the pharmacokinetics of tenofovir compared to administration in the fasting state. Food delays the time to reach tenofovir Cmax by approximately 1 hour. Tenofovir disoproxil fumarate may be administered without regard to meals.