Metoclopramide

Reglan is FDA-approved for short-term treatment of symptomatic gastroesophageal reflux disease (GERD) in adults who have failed to respond to conventional therapy, diabetic gastroparesis (delayed stomach emptying), and acute and recurrent diabetic gastric stasis. It is also used off-label for nausea and vomiting associated with chemotherapy, radiation therapy, and post-operative procedures, as well as for migraine-associated nausea.

Reglan works through two primary mechanisms: as a dopamine D2 receptor antagonist in the brain (which reduces nausea and vomiting signals) and as a 5-HT4 receptor agonist in the gastrointestinal tract (which increases acetylcholine release and stimulates gastric motility). This dual action accelerates gastric emptying and reduces symptoms of reflux and gastric stasis.

Reglan carries a black box warning for the risk of tardive dyskinesia (a potentially irreversible movement disorder) with long-term use or high doses. Common side effects include drowsiness, fatigue, headache, and insomnia. It may also cause extrapyramidal symptoms (EPS) such as muscle spasms and restlessness, particularly in younger patients. Reglan is contraindicated in patients with pheochromocytoma, bowel obstruction, perforation, or hemorrhage, and should be used with caution in patients with Parkinson's disease or a history of depression. Due to its effects on dopamine, it may interact with other dopamine-affecting medications and antipsychotics. Use during pregnancy should be avoided unless clearly necessary, as it may cause adverse effects in the fetus.