Metoclopramide

A dopamine antagonist used as a prokinetic and antiemetic drug.

What is Metoclopramide?

Metoclopramide is a centrally and peripherally acting dopamine D₂-receptor antagonist used to enhance gastrointestinal motility and control nausea and vomiting.

History & Background

Metoclopramide has been used for decades in the treatment of gastroparesis and chemotherapy-induced nausea, but requires careful dosing due to CNS effects.

Chemical Structure & Properties

• IUPAC name: 4-amino-5-chloro-N-(2-diethylaminoethyl)-2-methoxybenzamide
• Molecular formula: C₁₄H₂₂ClN₃O₂
• Molar mass: 299.80 g/mol
• Functional groups: Benzamide, amine

Mechanism of Action

Metoclopramide works by:

• Blocking dopamine D₂ receptors
• Enhancing acetylcholine release in the GI tract
• Increasing gastric emptying and intestinal motility

Pharmacokinetics

• Absorption: Rapid oral absorption
• Peak plasma time: 1–2 hours
• Metabolism: Liver
• Half-life: 5–6 hours
• Excretion: Urine

Medical Uses

• Gastroparesis (especially diabetic)
• Nausea and vomiting
• GERD (short-term use)
• Prevention of chemotherapy-induced nausea

Dosage Guidelines

Adults: 10 mg up to 3 times daily

Maximum duration: Usually not more than 12 weeks

⚠️ Long-term use increases risk of movement disorders.

Side Effects

• Drowsiness
• Restlessness
• Diarrhea
• Extrapyramidal symptoms

Warnings & Precautions

• Risk of tardive dyskinesia
• Avoid long-term continuous use
• Use caution in Parkinson’s disease

Drug Interactions

• Antipsychotics
• Levodopa
• Alcohol and sedatives

Frequently Asked Questions

Is metoclopramide better than domperidone? – Stronger but more CNS effects.

Can it cause tremors? – Yes, especially with prolonged use.

Does it cause sleep? – Can cause drowsiness.

Is it safe long-term? – Short-term preferred.

⚠️ Educational content only. Not a substitute for professional medical advice.