Stemetil

# Stemetil ## Overview - **Classification**: Phenothiazine antiemetic, antipsychotic. - **Mechanism**: Blocks dopamine D2 receptors in the chemoreceptor trigger zone (CTZ) to inhibit nausea/vomiting. Also has anticholinergic and antihistamine properties. ## Primary Indications 1. **Nausea & Vomiting** - Control of severe nausea and vomiting, including post-operative, chemotherapy-induced, or radiation sickness. 2. **Vertigo** - Management of vertigo associated with Ménière's disease and labyrinthitis. 3. **Migraine (adjunctive)** - For associated nausea and vomiting in acute migraine. ## Adult Dosing ### Standard Dosing **Nausea & Vomiting (Acute)** - **Dose (Oral)**: **5-10 mg** - **Frequency**: 2-3 times daily - **Route**: Oral (tablets, liquid) - **Max Daily Dose**: **40 mg** - **Dose (IM/IV)**: **5-10 mg** - **Frequency**: Every 3-4 hours as needed - **Route**: Intramuscular (IM), Intravenous (IV - slow infusion) - **Max Daily Dose (IM/IV)**: **20 mg** (IM), **40 mg** (IV, if severe/resistant) - **Special Considerations**: IV must be slow infusion (e.g., over 15-30 min) due to hypotension risk. **Nausea & Vomiting (Maintenance/Prophylaxis)** - **Dose (Oral)**: **5-10 mg** - **Frequency**: 2-3 times daily - **Route**: Oral - **Max Daily Dose**: **40 mg** **Vertigo** - **Dose (Oral)**: **5 mg** - **Frequency**: 3 times daily - **Route**: Oral - **Duration**: Initial treatment, may be reduced to **5-10 mg** daily for maintenance. ### Dose Adjustments - **Renal Impairment**: Use with caution. Consider dose reduction in severe impairment (CrCl < 10 mL/min). - **Hepatic Impairment**: Use with extreme caution. Significant dose reduction may be required due to impaired metabolism. - **Elderly Patients**: Start with lower doses (e.g., **2.5-5 mg** orally 1-2 times daily). Increased risk of sedation, hypotension, and extrapyramidal symptoms (EPS). ## Pediatric Dosing ### Neonates (0-28 days) - **Contraindicated**: Not recommended due to increased risk of extrapyramidal symptoms and other severe adverse effects. ### Infants (1-12 months) - **Contraindicated**: Not recommended due to increased risk of extrapyramidal symptoms and other severe adverse effects. ### Children (1-12 years) - **Indication**: Generally **not recommended** for children < 2 years or < **9 kg**. Only for severe, resistant nausea/vomiting, under specialist supervision. - **Dose (Oral/Rectal)**: **0.1 mg/kg/dose** - **Frequency**: 2-3 times daily (Max 3 doses in 24 hrs) - **Route**: Oral, Rectal (suppository) - **Maximum Single Dose**: **10 mg** - **Maximum Daily Dose**: **20 mg** - **Special Notes**: Monitor closely for EPS. Use for shortest possible duration. ### Adolescents (13-18 years) - **Dose (Oral)**: Can approach adult dosing, typically **5 mg** - **Frequency**: 2-3 times daily - **Route**: Oral, IM, IV - **Maximum Daily Dose**: **40 mg** - **Special Notes**: Start with lower end of adult dose range and titrate as tolerated. ## Safety Information ### Contraindications - **Absolute**: Hypersensitivity to prochlorperazine or phenothiazines. - **Absolute**: Comatose states, severe CNS depression. - **Absolute**: Children < 2 years or < **9 kg**. - **Absolute**: Bone marrow depression, pheochromocytoma. - **Relative**: Narrow-angle glaucoma, prostatic hypertrophy (anticholinergic effects). ### Common Adverse Effects - **Very Common (>10%)**: Sedation, drowsiness, dizziness. - **Common (1-10%)**: Dry mouth, blurred vision, constipation, orthostatic hypotension, extrapyramidal symptoms (EPS - dystonia, akathisia, parkinsonism). - **Serious but Rare**: Neuroleptic Malignant Syndrome (NMS), tardive dyskinesia, agranulocytosis, prolonged QT interval/arrhythmias. ### Key Drug Interactions - **CNS Depressants (alcohol, opioids, benzodiazepines)**: Potentiated sedation and respiratory depression. - **Anticholinergics (TCAs, antihistamines)**: Increased anticholinergic effects (dry mouth, blurred vision, constipation, urinary retention). - **Antihypertensives**: Increased risk of orthostatic hypotension. - **Dopamine Agonists (levodopa)**: Antagonism of anti-Parkinsonian effects. - **QT-prolonging drugs**: Increased risk of cardiac arrhythmias; use with caution. ## Monitoring & Follow-up - **Before Treatment**: Assess for pre-existing CNS depression, Parkinson's disease, or cardiac conditions. - **During Treatment**: Monitor for EPS (especially within first few days/weeks), sedation, orthostatic hypotension (BP monitoring). - **Clinical Signs**: Watch for involuntary muscle movements, restlessness, fever, altered mental status (signs of NMS). ## Clinical Pearls - 💡 **EPS Risk**: High risk of extrapyramidal symptoms, particularly in young children and the elderly. Alert patients to report unusual muscle movements. - 💡 **Administration**: IM route offers rapid relief for acute nausea/vomiting. IV administration must be slow due to risk of hypotension. - 💡 **Sedation**: Warn patients about potential drowsiness; advise against driving or operating machinery until effects are known. - 💡 **Hydration**: Maintain adequate hydration to help prevent orthostatic hypotension. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.