Chlorpheniramine Maleate

A classic first-generation antihistamine widely used in cold and cough formulations.

What is Chlorpheniramine?

Chlorpheniramine maleate is a first-generation antihistamine used to treat allergic symptoms such as sneezing, runny nose, watery eyes, itching, and nasal congestion.

It is commonly included in cold and flu combination medicines because it also helps reduce nasal secretions.

History & Background

Chlorpheniramine has been in medical use for several decades and became popular because of its strong antihistamine action and affordability. Despite causing drowsiness, it remains widely used.

Chemical Structure & Properties

• IUPAC name: 3-(4-chlorophenyl)-3-(pyridin-2-yl)propan-1-amine maleate
• Molecular formula: C₁₆H₁₉ClN₂ · C₄H₄O₄
• Molar mass: 390.86 g/mol (salt form)
• Functional groups: Amine, aromatic rings

Because of its lipophilic structure, chlorpheniramine easily crosses the blood–brain barrier, leading to sedation.

Mechanism of Action

Chlorpheniramine blocks histamine H₁ receptors both centrally and peripherally. This results in:

• Reduced sneezing and itching
• Decreased nasal discharge
• Relief from watery eyes

Its action on the central nervous system causes drowsiness.

Pharmacokinetics

• Absorption: Well absorbed orally
• Peak plasma time: 2–6 hours
• Protein binding: Moderate
• Metabolism: Liver
• Excretion: Urine

Medical Uses

• Common cold
• Allergic rhinitis
• Sneezing and runny nose
• Allergic conjunctivitis
• Cold-related nasal congestion

Dosage Guidelines

Adults: 4 mg every 4–6 hours

Children: As prescribed by doctor

⚠️ May cause drowsiness — avoid driving.

Side Effects

• Drowsiness
• Dry mouth
• Dizziness
• Blurred vision

Warnings & Precautions

• Not recommended with alcohol
• Use caution in glaucoma and prostate enlargement

Drug Interactions

• Alcohol
• Sedatives
• Other antihistamines

Chlorpheniramine vs Loratadine

Chlorpheniramine causes drowsiness, while loratadine is non-sedating.

Frequently Asked Questions

Is chlorpheniramine an antibiotic? – No.

Does it cause sleep? – Yes.

Is it safe for children? – Only under medical advice.

Why is it used at night? – Due to sedative effect.

⚠️ Educational content only. Not a substitute for professional medical advice.