title: Atenolol interaction with aspirin, allopurinol, and ampicillin.
abstract: Atenolol kinetics were investigated in six healthy subjects after 100 mg orally, as monotherapy a 6-day treatment began 48 hr later. After a therapy-free interval of 4 wk, the same subjects received the same dose of atenolol with 1 gm ampicillin, 500 mg aspirin, and with 300 mg allopurinol. Allopurinol and aspirin did not substantially alter the kinetics of atenolol. After a single oral dose of 100 mg atenolol combined with 1 gm ampicillin, the bioavailability of atenolol was reduced to 36 +/- 5% compared to 60 +/- 8% after monotherapy. During long-term treatment with atenolol and ampicillin the bioavailability of atenolol fell to 24% (P less than 0.01). Mean peak plasma levels were lowered from 511 +/- 59 ng/ml on monotherapy to 344 +/- 33 ng/ml after the combination with ampicillin. The area under the plasma level-time curve, mean steady-state concentration, and urinary recovery were reduced, also. Twelve hours after 100 mg atenolol and 1 gm ampicillin, exercise tachycardia was significantly higher than after atenolol alone. During the 4-wk treatment in six hypertensive patients blood pressure levels of those on atenolol alone were not different from those on the combination therapy with ampicillin.
mesh_terms: D000328:Adult; D000493:Allopurinol / Q000494:pharmacology*; D000667:Ampicillin / Q000494:pharmacology*; D001241:Aspirin / Q000494:pharmacology*; D001262:Atenolol / Q000378:metabolism* / Q000494:pharmacology; D001682:Biological Availability; D001794:Blood Pressure / Q000187:drug effects; D004347:Drug Interactions; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D008297:Male; D005082:Physical Exertion; D011412:Propanolamines / Q000378:metabolism*
chemical_list: D011412:Propanolamines; D001262:Atenolol; D000493:Allopurinol; D000667:Ampicillin; D001241:Aspirin