Antiemetic effect of metoclopramide is mainly due to its action as:: (A) 5HT3 antagonist, (B) D2 antagonist, (C) M3 antagonist, (D) 5HT4 agonist
Answer is B. Ans. (B) D2 antagonist(Ref: Katzung 13th/1070, KDT 8th/e p713)Metoclopramide has action on several receptors.Main action as anti-emetic is because of D2 receptor antagonism.Main action as prokinetic is because of 5HT4 agonism.Mechanism of actions of metoclopramideReceptorActionClinical effectD2AntagonismAnti-emetic5HT3AntagonismAnti-emeticProkinetic5HT4AgonismProkinetic