Home Drug Guide Chlorpromazine Hydrochloride

Drug Guide

Generic Name

Chlorpromazine Hydrochloride

Brand Names Thorazine, Sonazine, Promapar, Chlorpromazine Hydrochloride Intensol

Classification

Therapeutic: Antipsychotic (neuroleptic)

Pharmacological: Phenothiazine antipsychotic

FDA Approved Indications

Schizophrenia
Manic phases of bipolar disorder
^Prevention of nausea and vomiting
^Preoperative sedation

Mechanism of Action

Chlorpromazine acts by antagonizing dopamine D2 receptors in the central nervous system, leading to a decrease in dopaminergic neurotransmission, which alleviates psychotic symptoms.

Dosage and Administration

Adult: Initial dose: 25-50 mg 3-4 times daily; dosage can be adjusted based on response and tolerability.

Pediatric: Use is limited; consult specialist. Typical doses are 0.2 mg/kg/day divided into two or three doses.

Geriatric: Start at a lower dose, e.g., 25 mg/day, and titrate slowly.

Renal Impairment: Adjust dose based on clinical response and tolerability.

Hepatic Impairment: Use with caution; close monitoring recommended.

Pharmacokinetics

Absorption: Well absorbed orally.

Distribution: Widely distributed in body tissues; crosses the blood-brain barrier and placental barrier.

Metabolism: Primarily hepatic via CYP450 enzymes.

Excretion: Metabolites excreted in urine; unchanged drug minimally excreted in urine.

Half Life: Approximately 10-20 hours, varies with individual.

Contraindications

Coma, CNS depression, hypersensitivity to phenothiazines.

Precautions

Use with caution in patients with cardiovascular disease, Parkinson's disease, liver impairment, or a history of seizure disorders.
Pregnancy Category C; use only if potential benefit justifies risk. Lactation: use cautiously.

Adverse Reactions - Common

Sedation, dizziness (Common)
Dry mouth (Common)
Orthostatic hypotension (Common)

Adverse Reactions - Serious

Extrapyramidal symptoms (dystonia, Parkinsonism, akathisia) (Less common)
Neuroleptic malignant syndrome (Rare)
Prolonged QT interval, cardiac arrhythmias (Rare)
Agranulocytosis (Rare)

Drug-Drug Interactions

CNS depressants (enhanced sedation)
Anticholinergic drugs (additive side effects)
Agents prolonging QT interval (risk of arrhythmias)

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor mental status, cardiac function (ECG), blood counts, and EPS symptoms.

Diagnoses:

Risk for falls due to sedation or orthostatic hypotension.
Risk for injury from extrapyramidal symptoms.

Implementation: Administer with food to minimize GI upset. Educate patient on orthostatic precautions.

Evaluation: Assess symptom improvement and monitor for adverse effects.

Patient/Family Teaching

Take medication exactly as prescribed.
Change positions slowly to prevent dizziness.
Report any signs of EPS, fever, sore throat, or signs of allergic reactions.
Avoid alcohol and CNS depressants.

Special Considerations

Black Box Warnings:

Elderly patients with dementia-related psychosis treated with antipsychotics are at increased risk of death.

Genetic Factors: CYP2D6 poor metabolizers may have increased drug levels.

Lab Test Interference: May cause false-positive for catecholamine levels.

Overdose Management

Signs/Symptoms: Sedation, hypotension, extrapyramidal symptoms, coma, seizures.

Treatment: Supportive care; monitor vital signs; activated charcoal if ingestion recent; saline IV; for severe reactions, consider specific antidotes and intensive supportive measures.

Storage and Handling

Storage: Store at room temperature, 20-25°C (68-77°F).

Stability: Stable under proper conditions, check manufacturer label for specific details.