Chlorpromazine

Antipsychotic Drug

Drug class: Typical Antipsychotic

Chlorpromazine (LARGACTIL)（中文：氯丙嗪）

Common Strengths of Chlorpromazine Tablet

Chlorpromazine are available in the following strengths:

• Tablets: 25 mg, 50 mg, 100 mg

Drug Trade Names of Chlorpromazine Tablet

Largactil

Drug Usage

Treatment of schizophrenia and other psychotic disorders

Mechanism of Action

Chlorpromazine acts s an antagonist on various postsynaptic receptors:

• Blocks dopamine D₁, D₂, D₃, and D₄ receptors
• Blocks serotonin 5-HT₁ and 5-HT₂ receptors
• Blocks histamine H₁ receptors
• Blocks alpha-1 and alpha-2 adrenergic receptors
• Blocks muscarinic acetylcholine receptors

Route of Administration

Oral

Dosages

For schizophrenia in adults:

• Initial: 25 - 50 mg orally 3 times daily
• Maintenance: 200 - 400 mg daily in divided dose
• Maximum: 1000 mg daily

Side Effects

Frequency	Adverse reactions
Common	Drowsiness and sedation
	Dizziness
	Dry mouth
	Blurred vision
	Constipation
	Weight gain
	Increased appetite
	Nausea
	Difficulty urinating
	Skin sensitivity to sunlight
Serious	a. Exterapyramidal symptoms (movement disorders): Muscle stiffness or spasms Tremors Restlessness (akathisia) Parkinson-like symptoms
	b. Tardive dyskinesia (potentially irreversible involuntary movements of face and tongue)
	c. Neuroleptic malignant syndrome (fever, muscle rigidity, altered mental state)
	d. Low white blood cell count (agranulocytosis)
	e. Seizures
	f. QT prolongation leading to dangerous heart arrhythmias
	g. Difficulty regulating body temperature
	h. Hormonal changes: Increased prolactin levels Breast enlargement or milk production Menstrual changes
	i. Sever low blood pressure

Pharmacokinetics

• Absorption: Well absorbed orally, but undergoes extensive first-pass metabolism
• Metabolism: Extensively metabolized in the liver
• Elimination: Mainly in urine as metabolites
• Onset: 30 - 60 minutes after oral administration
• Duration: 4 - 6 hours (single dose), up to 24 hours (multiple doses)

Drug Precautions

Pregnancy

Use only if potential benefit outweighs risk. May cause extrapyramidal symptoms in newborns if used in 3rd trimester.

Breastfeeding

Use caution. Chlorpromazine is excreted in breast milk.

Children and Elderly

• Children: Use caution. Safety and efficacy not established in children < 1 year old.
• Elderly: Start at lower doses and titrate slowly due to increased sensitivity to side effects.

Renal Impairment

Use with caution. No specific dosage adjustments required.

Monitoring Requirements

• Blood pressure
• Body temperature
• Complete blood count
• Liver function tests
• Eye examinations
• ECG in patients at risk of QT prolongation

Drug Interactions

• Increased CNS depression with alcohol, barbiturates, opioids
• Increased risk of arrhythmias with drug that prolong QT interval
• Decreased effectiveness of levodopa
• Increased risk of extrapyramidal symptoms with metoclopramide

FAQ

How Should I Take the Tablet?

Take with or without food.

What Should I Avoid While Taking?

Avoid alcohol, driving or operating machinerty until you know how it affect you. Avoid excessive sun exposure.

What Happens if I Miss a Dose?

Take the missed dose as soon as you remember unless it is almost time for your next dose. Do not double doses.