High plasma concentrations of desmethylclomipramine after chronic administration of clomipramine to a poor metabolizer

Abstract
A patient showed excessive concentrations of desmethylclomipramine after receiving normal daily doses of clomipramine (Anafranil) and the elimination kinetics of the desmethylated metabolite was zero-order/saturable. Investigation showed that she was a poor metabolizer of debrisoquine and that, in addition, she had been treated with allopurinol, an inhibitor of hepatic drug metabolism.