Effect of pregnenolone-16alpha-carbonitrile (PCN) on drug response in man.

Pregnenolone-16alpha-carbonitrile (PCN), which alters drug responses and induces hepatic microsomal drugs-metabolizing enzymes in experimental animals, is well-tolerated in man. There were no marked changes in the concentrations of blood sugar and urea; marked changes in the concentrations of blood sugar and urea; bromsulphophthalein (BSP) clearance; serum alkaline phosphatase activity; hematocrit, erythrocyte and leukocyte counts; as well as in ecg patterns. When the steroid was given by mouth for 4 days to patients treated with electroshock for psychiatric disorders, it decreased suxamethonium-induced skeletal muscle fasciculation and shortened thiopentone as well as propanidid anaesthesia. Breathing was resumed more rapidly than in control subjects. The protective effect of PCN is probably mediated through induction of activation or hepatic drug-metabolizing enzymes, or both.