Drug Interactions between cephalexin and Xofluza

GENERALLY AVOID: Coadministration with foods or medications that contain polyvalent cations such as dairy products, calcium-fortified beverages, certain laxatives, antacids, or oral supplements may decrease the plasma concentrations and therapeutic efficacy of baloxavir. The proposed mechanism is chelation of baloxavir by polyvalent cations, forming a complex that is poorly absorbed from the gastrointestinal tract. A significant decrease in baloxavir exposure was observed in monkeys when the prodrug, baloxavir marboxil, was coadministered with calcium, aluminum, magnesium, or iron. However, clinical data in humans are lacking.

When baloxavir marboxil was administered with food, baloxavir peak plasma concentration (Cmax) and systemic exposure (AUC) decreased by 48% and 36%, respectively, relative to administration under fasting. These changes are not considered clinically significant.

MANAGEMENT: Baloxavir marboxil may be taken with or without food. However, coadministration with dairy products, calcium-fortified beverages, or polyvalent cation-containing laxatives, antacids, or oral supplements (e.g., calcium, iron, magnesium, selenium, or zinc) should be avoided.

ADJUST DOSING INTERVAL: Oral products containing zinc such as mineral supplements and multivitamins may interfere with the gastrointestinal absorption of cephalexin, ceftibuten or cephradine. In one pharmacokinetic study (n=12), concurrent administration of zinc sulfate (250 mg, single oral dose) and cephalexin (500 mg, single oral dose) decreased cephalexin maximum concentration (Cmax) and systemic exposure (AUC; 0-inf) by 31.05% and 27.4%, respectively. However, in the same study, when zinc sulfate was administered 3 hours after the cephalexin dose, no significant alteration in cephalexin pharmacokinetics were observed.

MANAGEMENT: Oral medications or mineral supplements that contain zinc are recommended to be administered at least 3 hours after the cephalexin, ceftibuten or cephradine dose.