Interactions between ampicillin and Atenolol (atenolol)
ampicillin and atenolol (Moderate Drug-Drug)
ADJUST DOSING INTERVAL: The oral coadministration of ampicillin and atenolol may result in decreased plasma concentrations of the latter, possibly due to impaired gastrointestinal absorption in the presence of ampicillin. In six healthy subjects, the bioavailability of a 100 mg dose of atenolol was 60% when given alone, 36% when administered with a single 1 gram dose of ampicillin, and 24% after repeated administration with ampicillin for 6 days. In another study, a 1 gram dose of ampicillin reduced the area under the plasma concentration-time curve (AUC) of atenolol by 51%, while ampicillin administered as 250 mg four times a day reduced atenolol AUC by only 18%.
MANAGEMENT: These results suggest that the interaction may be attenuated by dividing the ampicillin dosage into smaller, more frequent doses and/or staggering the times of administration of the two drugs.
