Metaclopramide all are true except ?
Ans. is 'b' i.e., D,-agonist Metaclopramide is D2-antagonist (not agonist). Metoclopramide Metoclopramide is aprokinetic drug. It has more prominent effect on upper GIT- increases gastric peristalsis, while relaxing the pylorus and the first pa of duodenum - speed gastric emptying. Tone of lower esophageal sphincter (LES) is increased and gastroesophageal reflux opposed. But has no significant action on colonic motility. An effective antiemetic. Mechanism of action. I. 5-HT4agonism - stimulation of 5-HT4 receptor in GIT enhances the release of ACH from myenteric plexus - Main prokinetic action of metoclopropamide is due to this action. D2 antagonism - Blockade of D2 receptor in CTZ is mainly responsible for antiemetic effect. D2 receptor blockade in GIT is responsible for some prokinetic action also. Adverse effects - Sedation, dizziness, loose stools, muscle dystonia (especially in children) are the main side effects. D2 -blocking action may cause extrapyramidal symptoms (Akathsia, Parkinsonism) and hyperprolactinemia (galactorrhea, gynacomastia).
Increase gastric emptying
D2-agonist
Acts on CTZ
Long term use can cause parkinsonism, galactorrhoea and gynaecomastia