Prochlorperazine

# Prochlorperazine ## Overview - **Classification**: Phenothiazine antipsychotic; antiemetic. - **Mechanism**: Blocks dopamine D2 receptors in the chemoreceptor trigger zone (CTZ) and post-synaptic mesolimbic dopamine receptors. Also has anticholinergic and alpha-adrenergic blocking effects. ## Primary Indications 1. **Nausea and Vomiting** - Management of severe nausea and vomiting. 2. **Anxiety (Non-Psychotic)** - Short-term management of severe non-psychotic anxiety. 3. **Migraine Headache** - Off-label use, often with antihistamine for acute treatment. ## Adult Dosing ### Standard Dosing **Nausea and Vomiting (Oral)** - **Dose**: **5-10 mg** - **Frequency**: 3-4 times daily - **Route**: PO - **Maximum**: **40 mg/day** **Nausea and Vomiting (Rectal)** - **Dose**: **25 mg** - **Frequency**: Twice daily - **Route**: PR (suppository) - **Maximum**: **50 mg/day** **Nausea and Vomiting (Intramuscular)** - **Dose**: **5-10 mg** - **Frequency**: Every 3-4 hours as needed - **Route**: IM - **Maximum**: **30 mg/day** **Nausea and Vomiting (Intravenous - *use with caution*)** - **Dose**: **2.5-10 mg** (slow push or infusion) - **Frequency**: Every 3-4 hours as needed - **Route**: IV (infuse over 15-30 min) - **Maximum**: **10 mg/dose**, **40 mg/day** **Anxiety (Oral)** - **Dose**: **5 mg** - **Frequency**: 3-4 times daily - **Route**: PO - **Maximum**: **20 mg/day** ### Dose Adjustments - **Renal Impairment**: Use with caution. Start at lower end of dosing range. - **Hepatic Impairment**: Use with caution. Reduced metabolism possible; monitor for increased side effects. - **Elderly Patients**: Start with lower doses (**2.5-5 mg**); more susceptible to adverse effects like EPS, orthostatic hypotension, and sedation. ## Pediatric Dosing ### Neonates (0-28 days) - **Contraindicated**: Due to potential for serious adverse effects, including dystonia and respiratory depression. ### Infants (1-12 months) - **Contraindicated**: Not recommended for children under 2 years or <9.1 kg. High risk of extrapyramidal symptoms (EPS). ### Children (2-12 years) **Nausea and Vomiting (Oral/Rectal) - *only if >9.1 kg*** - **Dose**: **0.1 mg/kg/dose** (range **0.06-0.125 mg/kg**) - **Frequency**: 3-4 times daily - **Maximum**: **10 mg/dose**, **30 mg/day** (oral) or **25 mg/day** (rectal) - **Special Notes**: Not for routine use. Use only when other antiemetics fail. Avoid in dehydrated children. **Nausea and Vomiting (IM) - *only if >9.1 kg*** - **Dose**: **0.1 mg/kg/dose** - **Frequency**: Every 3-4 hours as needed - **Maximum**: **10 mg/dose**, **30 mg/day** - **Special Notes**: Reserve for severe cases; higher risk of EPS in children. ### Adolescents (13-18 years) - **Dose**: Generally follow adult dosing, starting at the lower end of the range. - **Maximum**: Adult maximum doses apply. ## Safety Information ### Contraindications - **Absolute**: Hypersensitivity to prochlorperazine or phenothiazines. - **Absolute**: Comatose state, CNS depression. - **Absolute**: Children <2 years or <9.1 kg. - **Absolute**: Severe liver damage, blood dyscrasias. - **Absolute**: Narrow-angle glaucoma, prostatic hypertrophy (due to anticholinergic effects). ### Common Adverse Effects - **Very Common (>10%)**: Drowsiness, dizziness, dry mouth, blurred vision. - **Common (1-10%)**: Orthostatic hypotension, extrapyramidal symptoms (EPS - dystonia, akathisia, parkinsonism), constipation. - **Serious but Rare**: Neuroleptic Malignant Syndrome (NMS), tardive dyskinesia (TD), agranulocytosis, seizures, QT prolongation. ### Key Drug Interactions - **CNS Depressants (opioids, benzodiazepines, alcohol)**: Potentiated sedation, respiratory depression. Reduce doses of both agents. - **Anticholinergics (tricyclic antidepressants, antihistamines)**: Increased anticholinergic effects (e.g., dry mouth, urinary retention). - **Dopamine Agonists (levodopa)**: Prochlorperazine may reduce efficacy of dopamine agonists. Avoid concomitant use. - **Antihypertensives**: Exacerbated orthostatic hypotension. Monitor blood pressure closely. ## Monitoring & Follow-up - **Before Treatment**: Baseline vital signs, mental status, assessment of EPS risk factors. - **During Treatment**: Monitor for signs of EPS (dystonia, akathisia, parkinsonism) and NMS (fever, rigidity, altered mental status). Monitor blood pressure for orthostasis. - **Clinical Signs**: Watch for involuntary movements (TD), agitation, tremors, muscle spasms. Promptly report unexplained fever, muscle rigidity. ## Clinical Pearls - 💡 **Black Box Warning**: Increased mortality in elderly patients with dementia-related psychosis. Use extreme caution. - 💡 **EPS Management**: Acute dystonic reactions can be treated with **IV/IM benztropine 1-2 mg** or **diphenhydramine 25-50 mg**. - 💡 **IV Administration**: Administer IV doses slowly (over 15-30 minutes) to minimize risk of hypotension and EPS. - 💡 **Photosensitivity**: Advise patients to use sun protection as phenothiazines can cause photosensitivity. - 💡 **Formulations**: Available as oral tablets, ODT, IM/IV injection, and rectal suppositories for flexible administration. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.