Haloperidol

# Haloperidol ## Overview - **Classification**: First-generation (typical) antipsychotic, Butyrophenone derivative - **Mechanism**: Blocks postsynaptic D2 dopamine receptors in the mesolimbic system. Also has some alpha-1 adrenergic, anticholinergic, and antihistaminic activity. ## Primary Indications 1. **Acute Psychotic Disorders** - Management of schizophrenia, schizoaffective disorder. 2. **Acute Agitation** - Rapid tranquilization in patients with psychosis, mania, or delirium. 3. **Tourette's Syndrome** - Management of severe tics and vocalizations. 4. **Severe Nausea/Vomiting** - When other antiemetics are ineffective. ## Adult Dosing ### Standard Dosing **Acute Agitation/Psychosis (IM)** - **Dose**: **2-5 mg** - **Frequency**: May repeat every **30-60 minutes** as needed - **Route**: Intramuscular (IM) - **Maximum Dose**: Up to **10-20 mg** in 24 hours (variable by guideline) - **Considerations**: Start with lower doses for elderly/debilitated. **Acute Agitation/Psychosis (PO)** - **Dose**: **0.5-5 mg** - **Frequency**: 2-3 times daily - **Route**: Oral (PO) - **Maximum Dose**: Usually up to **30 mg/day** for psychosis. **Chronic Psychosis (PO)** - **Dose**: **0.5-5 mg** - **Frequency**: 2-3 times daily, or once daily (Haldol Decanoate IM every 4 weeks) - **Route**: Oral (PO) or Intramuscular (IM - decanoate) - **Maximum Dose**: Up to **30 mg/day** (oral); **100-200 mg** IM every 4 weeks (decanoate). **Nausea/Vomiting (Off-label)** - **Dose**: **0.5-2 mg** - **Frequency**: Every 4-8 hours as needed - **Route**: Oral (PO) or Intramuscular (IM) ### Dose Adjustments - **Renal Impairment**: No specific dose adjustment guidelines. Use with caution. Monitor for increased adverse effects. - **Hepatic Impairment**: Use with caution. Start with lower doses and titrate slowly. Monitor for adverse effects. - **Elderly Patients**: Start with **lower doses (e.g., 0.5-1 mg)** and titrate slowly due to increased sensitivity to adverse effects (EPS, QTc prolongation, sedation). Avoid in dementia-related psychosis. ## Pediatric Dosing ### Neonates (0-28 days) - **Haloperidol is not recommended** in neonates. - **Special Notes**: Use only if critically indicated under specialist supervision due to high risk of severe adverse effects (e.g., EPS, respiratory depression). ### Infants (1-12 months) - **Haloperidol use is generally not recommended** and is off-label. - **Special Notes**: Consider only in severe, refractory cases under specialist guidance. Risk of severe EPS is high. ### Children (1-12 years) **Psychotic Disorders, Tourette's Syndrome (Off-label <3 years)** - **Dose**: Initial **0.05-0.1 mg/kg/day** - **Frequency**: Divided into 2-3 doses daily - **Route**: Oral (PO) - **Maximum**: Not to exceed **0.15 mg/kg/day** or **10 mg/day**, whichever is less. - **Special Notes**: Titrate slowly. Monitor closely for EPS. **Acute Agitation (Off-label)** - **Dose**: **0.025-0.05 mg/kg** per dose - **Frequency**: May repeat every **30-60 minutes** - **Route**: Intramuscular (IM) - **Maximum**: Single dose max **5 mg**; total daily max **0.15 mg/kg/day** or **10 mg/day**. ### Adolescents (13-18 years) - **Dose**: Start with **0.5-2 mg** daily. - **Frequency**: Divided into 2-3 doses daily, or as a single IM dose for acute agitation. - **Maximum**: Up to **10 mg/day** (PO); up to **5 mg** IM per dose, total **10 mg/day**. - **Special Notes**: Generally, use lower end of adult dosing range. Monitor closely for EPS and QTc prolongation. ## Safety Information ### Contraindications - **Absolute**: Parkinson's disease or other severe CNS depression - **Absolute**: Comatose states - **Absolute**: Known hypersensitivity to haloperidol - **Absolute**: QTc prolongation or conditions that prolong QTc (e.g., hypokalemia, other QTc-prolonging drugs) - **Relative**: History of neuroleptic malignant syndrome (NMS) ### Common Adverse Effects - **Very Common (>10%)**: Extrapyramidal symptoms (EPS - dystonia, akathisia, parkinsonism), sedation - **Common (1-10%)**: Dizziness, blurred vision, dry mouth, constipation, orthostatic hypotension, weight gain - **Serious but Rare**: Neuroleptic Malignant Syndrome (NMS), Tardive Dyskinesia, QTc prolongation, Torsades de Pointes, agranulocytosis. ### Key Drug Interactions - **QTc-prolonging drugs**: Increased risk of Torsades de Pointes (e.g., Class IA/III antiarrhythmics, fluoxetine, moxifloxacin). **Avoid concomitant use.** - **CNS Depressants**: Enhanced sedation and respiratory depression (e.g., alcohol, benzodiazepines, opioids). **Monitor closely, reduce doses.** - **Dopamine Agonists**: Haloperidol antagonizes effects (e.g., levodopa, bromocriptine). **Avoid concomitant use for Parkinson's.** - **CYP3A4/2D6 Inhibitors**: May increase haloperidol levels (e.g., paroxetine, fluoxetine, quinidine, ketoconazole). **Monitor for toxicity, consider dose reduction.** ## Monitoring & Follow-up - **Before Treatment**: Baseline ECG, electrolytes (K+, Mg2+), liver function tests (LFTs), CBC. Rule out pregnancy. - **During Treatment**: - **ECG**: Baseline and periodically, especially with high doses, IV administration, or QTc risk factors. - **EPS**: Monitor for signs of dystonia, akathisia, parkinsonism, tardive dyskinesia at each visit. - **NMS**: Monitor for fever, muscle rigidity, altered mental status, autonomic instability. - **Vital Signs**: Blood pressure (orthostasis), heart rate. - **Clinical Signs**: Mental status, sedation, agitation, therapeutic response. - **Weight**: Periodically. ## Clinical Pearls - 💡 **Acute Agitation**: IM haloperidol often combined with IM benzodiazepine (e.g., lorazepam) for faster, more effective tranquilization (monitor for oversedation/respiratory depression). - 💡 **QTc Prolongation**: IV haloperidol carries higher risk than IM/PO. Always obtain baseline ECG and monitor during IV use. Correct hypokalemia/hypomagnesemia before administration. - 💡 **EPS Management**: Consider concomitant anticholinergic (e.g., benztropine) to prevent/treat EPS, especially with higher doses. - 💡 **Elderly/Delirium**: Use very low doses, monitor closely. Avoid in dementia-related psychosis due to increased mortality risk (FDA Black Box Warning). > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.