1. Clinical Overview
Haloperidol is a first-generation (typical) antipsychotic of the butyrophenone class. It is a potent dopamine D2 receptor antagonist with high affinity for the receptor. Primarily used in the management of schizophrenia, acute psychosis, and Tourette's syndrome, it is also a cornerstone for the rapid control of acute agitation and delirium. The 2mg/ml concentration is typically available as an oral solution and an injectable formulation (IM/IV) in India, allowing for flexible dosing and rapid intervention in acute settings.
| Onset | Duration | Bioavailability |
|---|---|---|
| Oral: 30-60 minutes; Intramuscular: 10-20 minutes; Intravenous: 5-10 minutes. | Oral/IM: 24-72 hours (due to long half-life); IV: Variable, but effects can persist for hours. | Approximately 60-70% orally due to first-pass metabolism. |
2. Mechanism of Action
Haloperidol exerts its primary antipsychotic effect through potent and central antagonism of postsynaptic dopamine D2 receptors in the mesolimbic pathway of the brain. This blockade reduces positive symptoms of psychosis (e.g., hallucinations, delusions). Its anti-emetic effect is due to D2 antagonism in the chemoreceptor trigger zone (CTZ).
3. Indications & Uses
- Schizophrenia (acute and maintenance treatment)
- Acute Psychotic Disorders
- Mania in Bipolar Disorder
- Tourette's Syndrome (for tic suppression)
- Severe Behavioral Problems (aggression, hyperexcitability)
4. Dosage & Administration
Adult Dosage: Psychosis: Initial: 0.5-5 mg 2-3 times daily (Oral/IM). Max: 100 mg/day in divided doses. Acute Agitation (IM): 2-5 mg, may repeat every 60 mins. Maintenance: Often 1-15 mg/day in divided doses or single HS dose.
Administration: Oral Solution: Use calibrated dropper/syringe. Can be diluted with water or juice. IM: Administer deep into a large muscle mass (gluteus maximus). Do NOT administer IV undiluted. For IV use (off-label in ICU): Must be diluted in NS or D5W and given as a slow IV push or infusion. Monitor ECG for QT prolongation.
5. Side Effects
Common side effects may include:
- Sedation/drowsiness
- Dry mouth
- Blurred vision
- Constipation
- Akathisia (motor restlessness)
- Parkinsonism (tremor, rigidity, bradykinesia)
- Dystonic reactions (spasms of neck, eyes, tongue)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| CYP3A4 Inhibitors (e.g., Ketoconazole, Clarithromycin, Fluoxetine) | Increased haloperidol plasma levels, risk of toxicity (EPS, sedation, QT prolongation) | Major |
| CYP3A4 Inducers (e.g., Carbamazepine, Phenytoin, Rifampicin) | Decreased haloperidol plasma levels, potential therapeutic failure | Major |
| Other CNS Depressants (Alcohol, Opioids, Benzodiazepines) | Additive CNS depression, respiratory depression risk | Major |
| QT-prolonging drugs (e.g., Amiodarone, Sotalol, Fluoroquinolones, TCAs) | Additive risk of QTc prolongation and Torsades de Pointes | Major |
| Anticholinergics (e.g., Trihexyphenidyl) | May reduce EPS but can worsen cognitive side effects and reduce antipsychotic efficacy | Moderate |
| Lithium | Increased risk of neurotoxicity (encephalopathy) and EPS | Major |
7. Patient Counselling
- DO take the medication exactly as prescribed. DO NOT double the dose if missed.
- DO use the calibrated dropper provided with the oral solution.
- DO NOT stop the medication abruptly without consulting your doctor.
- DO NOT consume alcohol or other sedatives.
- DO inform all your doctors and dentists you are taking haloperidol.
8. Toxicology & Storage
Overdose: Severe CNS depression (coma), hypotension or hypertension, extrapyramidal symptoms (severe dystonia, rigidity), agitation, restlessness, seizures, cardiac arrhythmias (QTc prolongation, Torsades de Pointes), neuroleptic malignant syndrome.
Storage: Store at room temperature (15-30°C). Protect from light and moisture. Keep the oral solution in its original amber-colored bottle. Keep out of reach of children. Do not freeze. Do not use if the solution is discolored or contains particulate matter.