Haloperidol Lactate Injection

Generic name: Haloperidol Lactate

Drug class: Antipsychotic (Butyrophenone derivative)

Dosage form: Injection (5 mg/mL)

Route of administration: Intramuscular (IM) injection

Dose:

• Adults:
• Acute agitation: 2–5 mg IM every 4–8 hours as needed, not exceeding 20 mg/day.
• Schizophrenia and acute psychosis: 2–5 mg IM every 4–8 hours as needed, not exceeding 20 mg/day. Transition to oral therapy as soon as feasible.
• Children (3–12 years):
• Acute agitation: 0.05–0.15 mg/kg/day orally in divided doses. Dosage should be titrated carefully based on response and tolerability.
• Special populations:
• Elderly patients: Start with half the lowest adult dose and titrate cautiously due to increased sensitivity.
• Patients with renal impairment: Dose adjustment may be necessary based on the degree of impairment.
• Patients with hepatic dysfunction: Dose reduction is generally recommended.

Mechanism of action: Haloperidol exerts potent antagonism at dopamine D2 receptors in mesolimbic and nigrostriatal pathways, accounting for antipsychotic efficacy but also conferring substantial risk of extrapyramidal symptoms (EPS) and hyperprolactinemia. It shows lower affinity for D1, 5-HT2, α1-adrenergic, and H1-histaminic receptors, which explains minimal anticholinergic and sedating properties relative to low-potency FGAs. Inhibition of D2 signaling in the chemoreceptor trigger zone also underlies its antiemetic effects.

Drug usage cases:

• Schizophrenia
• Acute psychosis
• Acute agitation
• Tourette syndrome with severe tics
• Off-label: Acute agitation in various settings

Drug contraindications:

• Severe toxic central nervous system depression or comatose states from any cause
• Hypersensitivity to haloperidol
• Parkinson’s disease
• Dementia with Lewy bodies

Side effects:

• Extrapyramidal symptoms (e.g., tremors, rigidity, bradykinesia)
• Hyperprolactinemia (e.g., galactorrhea, gynecomastia)
• QT interval prolongation
• Torsades de Pointes
• Sudden death
• Tachycardia
• Hypotension (including orthostatic hypotension)
• Cerebrovascular adverse reactions (e.g., stroke, transient ischemic attack)
• Neuroleptic malignant syndrome
• Seizures
• Anticholinergic effects (e.g., dry mouth, constipation, urinary retention)
• Weight gain
• Sexual dysfunction
• Photosensitivity
• Skin rash
• Elevated liver enzymes
• Leukopenia
• Agranulocytosis
• Thrombocytopenia
• Hemolytic anemia
• Electrolyte disturbances (e.g., hypokalemia, hypomagnesemia)

Warnings:

• Increased mortality in elderly patients with dementia-related psychosis
• QT interval prolongation and risk of Torsades de Pointes
• Not approved for intravenous administration; if administered intravenously, ECG monitoring is recommended
• Use with caution in patients with electrolyte imbalances, cardiac abnormalities, or a history of seizures
• Monitor for signs of neuroleptic malignant syndrome
• Use with caution in patients with a history of blood dyscrasias
• May lower the seizure threshold; use cautiously in patients with a history of seizures
• Use with caution in patients with a history of alcohol or drug abuse
• May cause drowsiness; caution when driving or operating heavy machinery
• Use with caution in patients with a history of glaucoma
• May cause anticholinergic effects; monitor for signs of urinary retention, constipation, and dry mouth
• Use with caution in patients with a history of cardiovascular disease
• May cause weight gain; monitor weight and metabolic parameters
• May cause sexual dysfunction; discuss potential side effects with patients
• Use with caution in patients with a history of photosensitivity
• May cause skin rash; discontinue if rash develops
• Monitor liver function tests during therapy
• Monitor blood counts during therapy
• Monitor for signs of hemolytic anemia
• Monitor electrolyte levels during therapy

Use during pregnancy or breastfeeding:

Pregnancy: Haloperidol is classified as a Pregnancy Category C drug. Animal studies have shown adverse effects on the fetus, but there are no adequate and well-controlled studies in pregnant women. Haloperidol should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Pregnant women should be closely monitored for any adverse effects.

Breastfeeding: Haloperidol is excreted in human milk. Due to the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother. Caution is advised when administering haloperidol to breastfeeding women.