Trilostane and the normal hypothalamic-pituitary-testicular axis.

Trilostane, a competitive inhibitor of the 3 beta-hydroxysteroid dehydrogenase enzyme system, has adrenal blocking activity and has been used to treat Cushing's syndrome and other disease. To investigate is effect on the normal human hypothalamic-pituitary-testicular axis, trilostane (initially 240 mg/day) was given to ten healthy adult males, the dose increasing at weekly intervals by 240 mg/day up to 960 mg/day. When chromatography was used to remove trilostane and metabolites from the assay system, serum testosterone was found to fall on trilostane therapy (P less than 0.01) and this was accompanied by a rise in LH (P less than 0.01). The responses of FSH and LH to LHRH were unaffected by treatment. It is concluded that trilostane inhibits human testicular 3 beta-hydroxysteroid dehydrogenase and male patients on trilostane should be monitored for sexual dysfunction and impairment of testicular steroidogenesis.