Mcp (Metoclopramide Hydrochloride)

Metoclopramide is an antiemetic that acts on dopamine pathways in the chemoreceptor trigger zone and the gastrointestinal tract.

• Nausea and vomiting: Reduces frequency and severity of acute and chemotherapy‑induced nausea and vomiting.
• Gastroparesis: Improves gastric emptying and alleviates associated symptoms such as early satiety and bloating.
• Functional dyspepsia: Relieves upper abdominal discomfort and post‑prandial fullness by enhancing GI motility.

• Metoclopramide exerts its therapeutic effect by antagonizing dopamine D2 receptors in the chemoreceptor trigger zone of the medulla, thereby suppressing the vomiting reflex. In the gastrointestinal tract it blocks D2 receptors on smooth muscle and enhances acetylcholine release, which increases the tone of the lower esophageal sphincter and promotes coordinated gastric contractions, leading to accelerated gastric emptying.

Metoclopramide may cause a range of adverse reactions, varying from mild to serious.

Common Side Effects

• Drowsiness: mild sedation or fatigue.
• Restlessness: feeling of inner tension or inability to stay still.
• Diarrhea: loose stools or increased bowel movements.
• Headache: mild to moderate head pain.
• Dry mouth: reduced salivation causing throat discomfort.

Serious or Rare Side Effects

• Extrapyramidal symptoms: muscle rigidity, tremor, or dystonia.
• Tardive dyskinesia: irreversible involuntary movements with long‑term use.
• Neuroleptic malignant syndrome: high fever, muscle rigidity, autonomic instability.
• Depression or suicidal thoughts: mood changes requiring immediate attention.
• Severe allergic reaction: rash, itching, swelling, or difficulty breathing.

When prescribing metoclopramide, clinicians should consider several safety precautions.

• Contraindication: avoid use in patients with known hypersensitivity to metoclopramide or other dopamine antagonists.
• Neurological risk: limit use in individuals with a history of seizure disorders or movement disorders.
• Duration of therapy: restrict treatment to the shortest effective period, generally not exceeding 12 weeks, to reduce risk of tardive dyskinesia.
• Pregnancy: use only if the potential benefit justifies the potential risk, as safety data are limited.
• Pediatric use: not recommended for children under 1 year of age without specialist supervision.
• Store at ambient temperature: keep below 25 °C, in the original container, protected from moisture and direct sunlight.

Metoclopramide can interact with several medicines, altering efficacy or safety.

Major Interactions (Avoid)

• Anticholinergic agents: may reduce pro‑kinetic effect and increase anticholinergic side effects.
• CNS depressants (e.g., opioids, benzodiazepines): additive sedation and respiratory depression.
• MAO inhibitors: risk of hypertensive crisis or severe CNS effects.

Moderate Interactions (Monitor Closely)

• CYP2D6 substrates (e.g., codeine, tramadol): metoclopramide may inhibit metabolism, increasing plasma levels.
• Antipsychotics (e.g., haloperidol): additive dopamine antagonism can worsen extrapyramidal symptoms.
• Digoxin: possible increase in serum digoxin concentrations.