Drug Interaction Report

ADJUST DOSING INTERVAL: Concomitant use of some oral medications may reduce the bioavailability of orally administered iron, and vice versa.

Food taken in conjunction with oral iron supplements may reduce the bioavailability of the iron. However, in many patients intolerable gastrointestinal side effects occur necessitating administration with food.

MANAGEMENT: Ideally, iron products should be taken on an empty stomach (i.e., at least 1 hour before or 2 hours after meals), but if this is not possible, administer with meals and monitor the patient more closely for a subtherapeutic effect. Some studies suggest administration of iron with ascorbic acid may enhance bioavailability. In addition, administration of oral iron products and some oral medications should be separated whenever the bioavailability of either agent may be decreased. Consult the product labeling for specific separation times and monitor clinical responses as appropriate.

Coadministration with a high-fat meal may decrease the rate and extent of alvimopan absorption. According to the product labeling, alvimopan peak plasma concentration (Cmax) and systemic exposure (AUC) were decreased by approximately 38% and 21%, respectively, and the time to reach peak plasma concentration (Tmax) was prolonged by approximately 1 hour when taken with a high-fat meal. The clinical significance is unknown. In postoperative ileus clinical trials, the preoperative dose of alvimopan was administered in a fasting state, and subsequent doses were given without regard to meals.