INTERACTION OF THE ALPHA-ADRENOCEPTOR AGONIST OXYMETAZOLINE WITH SEROTONIN 5-HT1A-RECEPTORS, 5-HT1B-RECEPTORS, 5-HT1C-RECEPTORS AND 5-HT1D-RECEPTORS

Oxymetazoline was recognized with nanomolar affinity by 5-HT1A, 5-HT1B and 5-HT1D binding sites and mimicked the effects of 5-hydroxytryptamine with about the same potency and intrinsic activity as the endogenous amine in the corresponding functional tests. At 5-HT1C receptors, oxymetazoline behaved as a mixed agonist-antagonist. Clonidine had minimal activity. Methiothepin antagonized the effects of oxymetazoline (7.4 < pK(B) < 8.8). Thus, oxymetazoline is a full and potent agonist at 5-HT1A, 5-HT1B and 5-HT1D receptors and a partial agonist at 5-HT1C receptors.