Tab Stemetil (prochlorperazine)

# Tab Stemetil (prochlorperazine) ## Overview Prochlorperazine is a phenothiazine derivative with potent antiemetic, antipsychotic, and anxiolytic properties. It acts primarily by blocking postsynaptic dopamine (D2) receptors in the mesolimbic system and the chemoreceptor trigger zone (CTZ). ## Primary Indications * Management of severe nausea and vomiting. * Short-term management of generalized anxiety (less common). * Treatment of schizophrenia and other psychotic disorders. ## Adult Dosing * **Nausea/Vomiting:** 5 mg to 10 mg orally 3 to 4 times daily. Maximum: 40 mg per day. * **Psychotic Disorders:** 5 mg to 10 mg orally 3 to 4 times daily. May be increased if necessary; maintenance doses usually range from 50 mg to 150 mg daily. ## Pediatric Dosing * **General Use:** Use is generally **not recommended** in children under 2 years of age or weighing less than 9 kg due to the increased risk of severe extrapyramidal symptoms (EPS) and respiratory depression. * **Children > 2 years/9 kg:** 2.5 mg orally 2 to 3 times daily. Do not exceed 10 mg daily for children 2–12 years old unless under strict specialist supervision. Dosing is highly protocol-dependent; consult local institutional guidelines for pediatric weight-based administration. ## Dose Adjustments * **Hepatic Impairment:** Use with caution; monitor for increased sensitivity to CNS effects. * **Renal Impairment:** No specific dosing adjustments, but monitor for accumulation. * **Geriatrics:** Start at the lower end of the dosing range (e.g., 2.5–5 mg) due to increased susceptibility to orthostatic hypotension and EPS. ## Contraindications * Hypersensitivity to prochlorperazine or other phenothiazines. * Comatose states or severe CNS depression. * Bone marrow depression. * History of blood dyscrasias. * Pediatric surgery (risk of paradoxical excitation). ## Adverse Effects * **Common:** Drowsiness, dizziness, dry mouth, blurred vision, constipation. * **Serious:** Extrapyramidal symptoms (dystonia, akathisia, parkinsonism), tardive dyskinesia, neuroleptic malignant syndrome (NMS), QT interval prolongation, and agranulocytosis. ## Key Drug Interactions * **CNS Depressants:** Alcohol, opioids, and sedatives may potentiate CNS/respiratory depression. * **QT-Prolonging Agents:** Avoid concurrent use with drugs that prolong the QT interval (e.g., ondansetron, ziprasidone, certain antibiotics). * **Anticholinergics:** May increase risk of anticholinergic toxicity. * **Dopaminergic agents:** Antagonizes the effects of antiparkinsonian drugs (e.g., levodopa). ## Monitoring * **Baseline:** Baseline ECG if high-risk for cardiac arrhythmias. * **Ongoing:** Monitor for signs of EPS (muscle stiffness, tremors) and NMS (fever, rigidity). Periodic CBC if used long-term for potential hematologic impact. ## Clinical Pearls * **Dystonic Reactions:** Acute dystonic reactions are relatively common in children and young adults; manage with parenteral anticholinergics (e.g., benztropine or diphenhydramine). * **Not for Routine Use:** Due to the risk of EPS and sedation, it should not be used for mild nausea or as a first-line agent in children. * **Tardive Dyskinesia:** Risk increases with long-term use; minimize duration of therapy. *** *Disclaimer: This information is for educational purposes and does not replace professional clinical judgment. Always verify current prescribing information, local hospital protocols, and manufacturer labels before administering medication.*