Metoclopramide is a potent antiemetic and prokinetic agent. It is a dopamine D2 receptor antagonist and a 5-HT4 receptor agonist, with weak 5-HT3 receptor antagonistic properties. It is widely used in the Indian clinical setting for the management of nausea, vomiting, and gastroparesis. The 5mg/ml concentration is commonly available as an oral solution and an injectable formulation.
Adult: Oral/IV/IM: 10 mg 3-4 times daily, 30 minutes before meals and at bedtime. For diabetic gastroparesis: 10 mg before each meal and at bedtime for 2-8 weeks. Max single dose: 20 mg. For PONV prophylaxis: 10 mg IM near end of surgery.
Note: Oral solution: Use calibrated measuring device. Administer 30 minutes before meals. Injectable: Can be given IV (slow push over 1-2 minutes) or IM. Do not use IV for chemotherapy-induced emesis if solution is discolored or contains precipitate.
Metoclopramide exerts its antiemetic effect by antagonizing dopamine D2 receptors in the chemoreceptor trigger zone (CTZ) of the area postrema in the medulla oblongata. Its prokinetic effect is mediated through a dual mechanism: 1) Cholinergic stimulation via sensitization of muscarinic receptors on GI smooth muscle to acetylcholine, and 2) Direct agonism of 5-HT4 receptors in the myenteric plexus, which enhances acetylcholine release. It also possesses weak 5-HT3 receptor antagonism.
Pregnancy: Category B (US FDA). Use only if clearly needed, especially in first trimester. Risk of EPS in newborn if used in third trimester. Avoid high doses or prolonged use.
Driving: May cause drowsiness, dizziness, and dystonic reactions. Patients should not drive or operate machinery until their response is known.
| Levodopa, Bromocriptine, Ropinirole | Mutual antagonism of therapeutic effects | Major |
| Antipsychotics (e.g., Haloperidol, Risperidone) | Additive risk of extrapyramidal symptoms | Major |
| Alcohol, CNS Depressants (Benzodiazepines, Opioids) | Additive sedation and CNS depression | Moderate |
| Anticholinergics (e.g., Atropine, Dicyclomine) | Antagonizes prokinetic effect of metoclopramide | Moderate |
| Serotonergic drugs (SSRIs, SNRIs, Tramadol) | Increased risk of serotonin syndrome | Moderate |
| Digoxin | May decrease digoxin absorption (reduced gastric emptying time) | Minor |
| Cyclosporine | Increased cyclosporine absorption and levels | Moderate |
| Succinylcholine | Prolonged neuromuscular blockade | Moderate |