5-HT1A-agonistic properties of naftopidil, a novel antihypertensive drug.

Naftopidil, a novel antihypertensive compound, possesses 5-HT1A agonistic properties in addition to being an alpha 1-adrenoceptor antagonist. The IC50 values for alpha 1-adrenoceptors (235 nmol/l) and for 5-HT1A receptors (108 nmol/l) lie in the same concentration range. The reduction in blood pressure of anesthetized cats by 8-OH-DPAT and urapidil was completely abolished by spiroxatrine, a 5-HT1A antagonist. However, the decreases in blood pressure induced by naftopidil were only partly antagonized by spiroxatrine.