Acebutolol metabolite plasma concentration during chronic oral therapy.

1 We have measured the plasma concentration of acebutolol and a major metabolite in patients on chronic oral therapy with this drug, using a new assay, specific for each species. Our study suggests: 2 The acetyl metabolite was present in concentrations greater than those of acebutolol at all times during the dosing interval in all seven subjects. 3 The ratio of the mean steady-state plasma concentrations of the acetyl metabolite to unchanged acebutolol was 2.7 +/- 1.0. 4 Previous studies using non-specific methods that measure plasma concentrations of the acetyl metabolite and acebutolol as a single species cannot be used to determine pharmacokinetic parameters or to provide reliable correlations of plasma drug concentration with effect. 5 Future studies determining plasma concentration of acebutolol should take this metabolite into account. 6 Further work will be necessary to determine the metabolite's contribution to acebutolol's effects in man.