Orap (Pimozide)

Pimozide is indicated for disorders that involve dopaminergic dysregulation, primarily within the central nervous system.

• Tourette syndrome: reduces the frequency and severity of motor and vocal tics.
• Chronic schizophrenia: alleviates psychotic symptoms such as delusions and hallucinations.
• Persistent behavioral disorders: helps control severe repetitive behaviors when other therapies are insufficient.

• Pimozide exerts its therapeutic effect by selectively antagonizing dopamine D2 receptors in the brain, thereby decreasing dopaminergic neurotransmission. It also blocks serotonin 5‑HT2 and alpha‑adrenergic receptors, contributing to its antipsychotic and anti‑tremor properties.

Pimozide may cause a range of adverse reactions, from mild to severe.

Common Side Effects

• Sedation: feeling unusually drowsy or sleepy.
• Extrapyramidal symptoms: muscle stiffness, tremor, or restlessness.
• Dry mouth: reduced salivation leading to discomfort.
• Constipation: slowed gastrointestinal motility.
• Blurred vision: temporary visual disturbances.
• Weight gain: increase in body weight over time.

Serious or Rare Side Effects

• Tardive dyskinesia: involuntary, repetitive movements that may be irreversible.
• Neuroleptic malignant syndrome: life‑threatening reaction with fever, muscle rigidity, and autonomic instability.
• QT interval prolongation: risk of serious cardiac arrhythmias.
• Severe hypotension: marked drop in blood pressure causing dizziness or fainting.
• Agranulocytosis: dangerously low white‑blood‑cell count increasing infection risk.

Before initiating pimozide therapy, several safety considerations should be reviewed.

• Cardiac monitoring: obtain baseline ECG and monitor QT interval during treatment.
• QT prolongation risk: avoid in patients with known prolonged QT or electrolyte disturbances.
• Hepatic impairment: adjust dose or monitor liver function tests closely.
• Elderly patients: increased susceptibility to falls and orthostatic hypotension.
• Pregnancy and lactation: use only if potential benefit justifies potential risk to fetus or infant.
• Store at room temperature: keep in the original container, protect from moisture and direct sunlight.

Pimozide can interact with other medicines, altering its effectiveness or safety profile.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, erythromycin): may raise pimozide plasma levels and increase toxicity.
• Strong CYP3A4 inducers (e.g., rifampin, carbamazepine): can lower pimozide concentrations, reducing efficacy.
• Other QT‑prolonging agents (e.g., quinidine, sotalol): additive risk of cardiac arrhythmias.

Moderate Interactions (Monitor Closely)

• Antihypertensives: pimozide may enhance blood‑pressure‑lowering effects.
• Concurrent antipsychotics: increased likelihood of extrapyramidal symptoms.
• Alcohol: potentiates central nervous system depression and sedation.