Prochlorperazine is a piperazine phenothiazine derivative with potent antiemetic, antipsychotic, and neuroleptic properties. It acts primarily as a dopamine D2 receptor antagonist in the chemoreceptor trigger zone (CTZ) and mesolimbic pathways. In the Indian context, it is widely used for the management of severe nausea and vomiting, vertigo, and as an adjunct in psychotic disorders, though its use as a first-line antipsychotic has declined in favor of atypical agents.
Adult: Nausea/Vomiting: 5-10 mg orally 3-4 times daily. Max: 40 mg/day. Vertigo: 5 mg orally twice daily to 10 mg thrice daily. Psychosis: Starting dose 5-10 mg orally 3-4 times daily; may increase gradually. Maintenance: 50-100 mg/day in divided doses.
Note: Take with or after food to minimize gastric irritation. Swallow tablet whole with a full glass of water. Do not crush or chew. Avoid alcohol. For bedridden patients, monitor for orthostatic hypotension. Do not stop abruptly after long-term use.
Prochlorperazine exerts its primary antiemetic effect by blocking dopamine D2 receptors in the chemoreceptor trigger zone (CTZ) of the area postrema, which lacks a blood-brain barrier. Its antipsychotic and neuroleptic effects are mediated through antagonism of dopaminergic (D2) transmission in the mesolimbic and mesocortical pathways of the brain. It also possesses weak anticholinergic, alpha-1 adrenergic blocking, and histamine H1 blocking properties.
Pregnancy: Category C: Animal studies show risk, human data limited. Use only if potential benefit justifies potential fetal risk. Avoid in first trimester. Risk of EPS or withdrawal in neonate if used near delivery.
Driving: May cause drowsiness, dizziness, and blurred vision. Patients should not drive or operate machinery until their response is known.
| CNS Depressants (Alcohol, Opioids, Benzodiazepines) | Additive CNS depression, respiratory depression, hypotension | Major |
| Anticholinergics (Trihexyphenidyl, Atropine) | Increased anticholinergic side effects (dry mouth, constipation, urinary retention); may decrease antipsychotic efficacy | Moderate |
| Levodopa, Dopamine Agonists | Mutual antagonism of therapeutic effects | Major |
| QT-prolonging drugs (Amiodarone, Sotalol, Fluoroquinolones) | Increased risk of Torsades de Pointes arrhythmia | Major |
| Antihypertensives | Potentiated hypotensive effect | Moderate |
| CYP2D6 Inhibitors (Fluoxetine, Paroxetine, Quinidine) | Increased prochlorperazine plasma levels, risk of toxicity | Moderate |