Haloperidol (Haldol)

QTc Prolongation - This is the big one perioperatively. Check a baseline QTc before giving IV haloperidol, especially if the patient is on other QT-prolonging drugs (ondansetron, methadone, droperidol). Hold or reconsider if QTc >500 ms.

Antiemetic Use - Works well for postoperative nausea and vomiting (PONV), particularly in opioid-heavy cases or patients at high PONV risk. Low doses (0.5-1 mg IV) are effective with a better safety profile than higher antipsychotic doses.

Agitation/Delirium - Useful for managing emergence agitation or ICU delirium. Doesn't cause respiratory depression at typical doses, which makes it handy when you want to calm a patient without blunting their airway reflexes.

EPS Risk - Dystonic reactions and akathisia can occur even with single doses. Diphenhydramine (25-50 mg IV) or benztropine (1-2 mg IV) treats acute dystonia quickly.

NMS - Rare but life-threatening — watch for hyperthermia, rigidity, autonomic instability, and elevated CK. Stop the drug, provide supportive care; dantrolene and bromocriptine have been used.

Excessive Effect - Oversedation is managed supportively. No reversal agent exists; QTc prolongation resolves as drug clears, but treat torsades de pointes with magnesium sulfate (2 g IV).

Drug Interactions - Additive QTc prolongation with ondansetron, methadone, amiodarone, azithromycin. Enhances CNS depression with opioids, benzos, and volatile anesthetics. May antagonize dopaminergic effects of medications used for Parkinson's disease.

Pediatric Implications - Used in pediatric patients for agitation and delirium, but EPS risk is higher in children and adolescents. Dose conservatively (0.01-0.05 mg/kg IV). Same QTc monitoring applies.

Obstetric Implications - Crosses the placenta. Neonatal EPS and withdrawal have been reported with third-trimester exposure. Use only if clearly needed; avoid near delivery if possible. Compatible with breastfeeding in low doses per most guidelines.

Absolute:

Known hypersensitivity to haloperidol

Parkinson's disease or Lewy body dementia

QTc >500 ms

Relative:

Concurrent QT-prolonging medications

Hypokalemia or hypomagnesemia (correctable before use)

Seizure disorder

Caution:

Elderly patients (increased risk of cerebrovascular events and mortality)

Hepatic impairment

Patients on anticoagulation (some formulations contain benzyl alcohol)

Antiemetic/agitation: 0.5-1 mg IV; may repeat q30 min PRN

Severe agitation/delirium: 2-5 mg IV; titrate to effect

2-5 mg IM; onset slower than IV (20-40 min)

Blocks central dopamine D2 receptors in the mesolimbic pathway (antipsychotic effect) and chemoreceptor trigger zone (antiemetic effect). Also has some alpha-1 adrenergic and histamine H1 blockade.

Hepatic

Renal and biliary

Black box warning: increased mortality in elderly patients with dementia-related psychosis

IV formulation is off-label for most uses but widely accepted in perioperative and ICU practice

Decanoate (long-acting IM depot) form is not for acute perioperative use