chlorphenamine maleate: clinical use

Prescribing considerations

• Consider sedation, antimuscarinic burden and impaired psychomotor performance, particularly in older people and children.
• Children and older people may develop paradoxical excitation, restlessness or confusion.
• Use caution in epilepsy, glaucoma or raised intraocular pressure, prostatic enlargement or urinary retention, cardiovascular disease or severe hypertension, obstructive respiratory disease, thyrotoxicosis, and hepatic or renal impairment.
• In suspected anaphylaxis, injection is adjunctive and must not delay adrenaline or emergency support.
• Verify the exact product licence, excipients and age restrictions.

Contraindications and cautions

• Hypersensitivity to chlorphenamine or a product excipient.
• Current or recent monoamine oxidase inhibitor use.
• The selected syrup additionally lists acute asthma and use in premature infants or neonates.
• Observe product-specific excipient restrictions, including lactose in the selected tablets and maltitol in the selected syrup.

Monitoring

• Assess sedation, dizziness, blurred vision, coordination and ability to perform skilled tasks.
• Monitor for dry mouth, urinary retention, confusion and thickened bronchial secretions.
• Consider paradoxical excitation or neurological effects in children and older adults.
• Investigate jaundice, abnormal bleeding or bruising, severe skin reactions, palpitations or persistent urinary symptoms.
• During breastfeeding, monitor the infant for sedation, irritability, poor feeding and weight gain.

Clinical pharmacology

A competitive H1-receptor antagonist with antimuscarinic activity. It crosses the blood–brain barrier, is widely distributed, substantially protein-bound and mainly metabolised before urinary elimination.

Formulation and product differences

• The selected tablet is scored and contains lactose.
• The selected syrup contains maltitol, sodium benzoate and a small amount of ethanol; it is measured with an oral syringe.
• Selected injections are clear solutions for intravenous, intramuscular or subcutaneous administration. Rapid intravenous injection can cause hypotension or central nervous system stimulation.
• Injection products contain sodium chloride and water for injections and are essentially sodium-free at the stated formulation volume.

Syrup

Route: Oral

Strengths: 2 mg/5 mL

Tablet

Route: Oral

Strengths: 4 mg

Injection

Route: Parenteral

Strengths: 10 mg/mL