The effect of pirenzepine (LS 519), a specific antimuscarinic drug, on cortisol levels in man

The authors investigated the effect of a single 75‐mg oral dose of pirenzepine, a drug which selectively blocks the muscarinic receptors and does not cross the blood‐brain barrier, on the function of the HPA axis. A significant decrease in basal cortisol values following the administration of the drug was observed in comparison with a placebo test. Moreover, the adrenal response to exogenous adrenocorticotropin (ACTH) administration was unchanged following a 5‐day course of the drug, ruling out direct action of pirenzepine at the adrenal level. These data suggest that cholinergic muscarinic hypothalamic and/or pituitary systems may be involved in the regulation of ACTH‐cortisol secretion.