What is the recommended dosing and administration of injectable (intramuscular) haloperidol for a patient with agitation or psychosis, considering potential cardiac risk factors and history of antipsychotic medication use?

Injectable Haloperidol Dosing and Administration

For acute agitation or psychosis, administer 2.5-5 mg IM haloperidol initially, with repeat doses of 2.5-10 mg every 4-6 hours as needed, not exceeding 10-15 mg total daily dose for maximum benefit while minimizing cardiac and extrapyramidal risks. 1

Standard Adult Dosing for Acute Agitation

• Initial dose: 5 mg IM haloperidol is the most commonly studied and recommended starting point for acute agitation in adults 2, 1
• Repeat dosing: 2.5-10 mg every 4-6 hours as needed for persistent agitation 1
• Maximum effective dose: 10-15 mg total provides optimal benefit; doses above 15 mg show no additional efficacy and increase adverse effects 1
• Consider combination therapy with lorazepam 2 mg IM for faster onset and superior agitation control compared to haloperidol alone 1

Elderly Patients (≥65 years)

Start with 0.25-0.5 mg IM haloperidol in elderly patients, as this population requires substantially lower doses 3:

• Initial dose: 0.25-0.5 mg IM, repeatable every 1-2 hours as needed 3
• Maximum daily dose: 5 mg in elderly patients 3
• Low-dose haloperidol (≤0.5 mg) demonstrates similar efficacy to higher doses with better outcomes including shorter hospital stays, less restraint use, and improved discharge disposition 4
• Higher risk of extrapyramidal symptoms in this population necessitates cautious dosing 3

First-Episode Psychosis

For patients with first-episode psychosis, use lower doses to preserve future medication adherence 1:

• Maximum 4-6 mg/day recommended for first-episode patients 1
• Lower doses (2 mg/day) are equally effective as higher doses (8 mg/day) but better tolerated with fewer extrapyramidal side effects 5
• Dose increases should occur at widely spaced intervals (14-21 days) if response is inadequate 1

Cardiac Risk Assessment and Contraindications

Do not use haloperidol in patients at significant risk for torsades de pointes 2:

• Absolute contraindications include:

  • Baseline QT prolongation
  • Concomitant QT-prolonging medications
  • History of torsades de pointes arrhythmia 2

• While torsades de pointes is rare with therapeutic IM haloperidol doses, the high morbidity and mortality associated with this complication warrants avoidance in high-risk patients 2

• No clear causal link exists between therapeutic haloperidol doses and sudden death, but dose-dependent QT prolongation has been documented 2

ICU and Delirium Considerations

For mechanically ventilated ICU patients with delirium:

• Haloperidol 1-10 mg IV every 2 hours as needed is commonly used, though sufficiently powered trials demonstrating clear benefit are lacking 2
• Consider dexmedetomidine over benzodiazepines for sedation to reduce delirium duration 2
• Do not use rivastigmine for delirium treatment, as it increases delirium severity and duration 2

Comparative Efficacy

• Haloperidol 5 mg IM demonstrates slower onset (28.3 minutes) compared to droperidol but remains effective 1
• Haloperidol 7.5 mg IM is equivalent in efficacy to olanzapine 10 mg IM for acute agitation 1
• Haloperidol shows superior efficacy compared to levosulpiride for psychotic symptoms and aggression, though with higher rates of extrapyramidal symptoms 6

Common Pitfalls to Avoid

• Avoid excessive dosing: Doses above 15 mg provide no additional benefit and increase adverse effects 1
• Do not use standard adult doses in elderly patients: This population requires 5-10 times lower doses 3
• Monitor for extrapyramidal symptoms: These compromise long-term medication adherence, particularly in first-episode patients 1
• Screen for cardiac risk factors before administration: QT prolongation risk necessitates careful patient selection 2