Drug Interaction Report

ADJUST DOSING INTERVAL: Food enhances the oral bioavailability of cefpodoxime proxetil tablets. Following a 200 mg dose taken with food, the extent of absorption (mean AUC) was 21% to 33% higher and the mean peak plasma concentration (Cmax) 19% higher than under fasting conditions. Time to peak concentration (Tmax) was not significantly different between fed and fasted states. On the contrary, when a 200 mg dose of the suspension was taken with food, the mean AUC and Cmax were not significantly different than those under fasting conditions, although the rate of absorption was slower with food (48% increase in Tmax ).

MANAGEMENT: To ensure maximal oral absorption, cefpodoxime proxetil tablets should be administered with or immediately after a meal.

ADJUST DOSING INTERVAL: The bioavailability of metoprolol may be enhanced by food.

MANAGEMENT: Patients may be instructed to take metoprolol at the same time each day, preferably with or immediately following meals.

ADJUST DOSING INTERVAL: Concurrent administration with calcium salts may decrease the oral bioavailability of atenolol and possibly other beta-blockers. The exact mechanism of interaction is unknown. In six healthy subjects, calcium 500 mg (as lactate, carbonate, and gluconate) reduced the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of atenolol (100 mg) by 51% and 32%, respectively. The elimination half-life increased by 44%. Twelve hours after the combination, beta-blocking activity (as indicated by inhibition of exercise tachycardia) was reduced compared to that with atenolol alone. However, during a 4-week treatment in six hypertensive patients, there was no difference in blood pressure values between treatments. The investigators suggest that prolongation of the elimination half-life induced by calcium coadministration may have led to atenolol cumulation during long-term dosing, which compensated for the reduced bioavailability.

MANAGEMENT: It may help to separate the administration times of beta-blockers and calcium products by at least 2 hours. Patients should be monitored for potentially diminished beta-blocking effects following the addition of calcium therapy.