Studies on the metabolism of perhexiline in man.

We have studied the disposition of perhexiline and its two major metabolites, M1 and M3, in healthy volunteers and in patients with biliary T-tube drains after cholecystectomy. In healthy volunteers the genetic control for impaired hepatic oxidation is identical for debrisoquine, sparteine, and perhexiline. Poor metabolizers demonstrate markedly reduced production and excretion of the major metabolite, M1. Their production of M3 is also reduced, but to a lesser degree than for M1, confirming substrate stereoselectivity by hepatic oxidases. Biphasic urinary elimination of M1 and M3 is seen in intact extensive oxidizers, whereas only the first phase is apparent in patients with biliary T-tube drainage. This suggests the possibility of enterohepatic recycling of these compounds, which may account for their prolonged elimination. More than 90% of an ingested dose of perhexiline maleate remains unaccounted for at 24 h after ingestion, even in extensive metabolizers. A careful, radiolabelled tissue-distribution study is warranted to elucidate the complicated metabolic fate of perhexiline.