Drug Interaction Report

MONITOR: Certain medications may decrease chemotaxis and cause false-negative results with Indium In-111-labeled leukocyte studies.

MANAGEMENT: Clinicians should be aware of possible diagnostic interference in patients who are on long-term antibiotic treatment, corticosteroids, interleukin-2, parenteral nutrition, or high doses or supratherapeutic concentrations of lidocaine or procainamide.

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.