NCIt definition : The tartrate salt form of metyrapone, a pyridine derivative and an inhibitor of steroid
11-beta-hydroxylase with anti-adrenal activity. Metyrapone inhibits steroid 11-beta-hydroxylase,
thereby inhibiting the synthesis of cortisol from 11-deoxycortisol, and corticosterone,
the precursor of aldosterone, from deoxycorticosterone in the adrenal gland. Removal
of the negative feedback mechanism exerted by cortisol results in increased adrenocorticotropic
hormone (ACTH) secretion by the pituitary gland. In turn, continued stimulation of
the adrenal gland by ACTH results in the accumulation of corticoid precursors, 11-deoxycortisol
and deoxycorticosterone. These corticoid precursors are excreted in urine and may
be used as indicators for hypothalamic-pituitary ACTH function.;