Absorption, half-life, and toxicity of oral aprindine in patients with acute myocardial infarction.

Plasma concentrations of aprindine were used to assess its absorption, toxicity and disappearance rate after oral administration to patients within 24 hours of admission to a coronary care unit. Despite high oral doses, absorption was so slow that in half the patients effective plasma levels (exceeding 0.70 mug/ml) were not found during the first 12 hours of treatment. Therefore the oral route should not be used to treat cases of acute myocardial infarction with severe ventricular dysrhythmias. Clinical tolerance was good; there was one episode of delirium tremens in a chronic alcoholic (aprindine plasma concentration: 3 mug/ml); no case of tremor or cerebellar syndrome was observed. Disappearance of aprindine from plasma was slow, by far exceeding the half-lives found in healthy volunteers, and ranging from 20 to over 100 h. The variability of biological half-life in individual patients makes plasma level determiniations necessary whenever aprindine is to be administered for a long period.