Muscarinic receptor blockade by pirenzepine: effect on prolactin secretion in man

The effect of pirenzepine, a muscarinic receptor blocker which does not cross the blood brain barrier, on basal and TRH-stimulated prolactin (PRL) secretion in normal subjects was studied. Administration of 75 mg oral pirenzepine had no effects on prolactin levels in male subjects whereas it significantly reduced prolactin in females. No effect on TRH induced prolactin secretion was observed.