Disposition of bethanidine, N-benzyl-N',N''-dimethylguanidine, in the rat, dog and man.

Bethanidine is metabolized in the rat and dog to a significant degree to N-benzyl-N'-methylguanidine, N-benzylguanidine, N-hydroxybenzyl-N'-methylguanidine, N-methylguanidine, N-hydroxybenzyl-N',N''-di-methylguanidine, and benzoic acid, whereas in man the drug is not metabolized. It is readily absorbed in all three species. The elimination kinetics in man show a difference between the urinary excretion rate and the rate of decline in the blood. Whole body autoradiograms showed a high concentration of drug in rat tissues rich in adrenergic nerve terminals, but insignificant penetration, if any, of the blood-brain barrier.