chlorphenamine maleate + pseudoephedrine hydrochloride: clinical use

Prescribing considerations

• Confirm allergic rhinitis and whether both an antihistamine and systemic decongestant are appropriate.
• Review cardiovascular, renal, hepatic, ocular, endocrine, neurological and urinary history.
• Review concurrent cough, cold, sympathomimetic, sedative and anticholinergic products.
• Counsel about sedation and the very rare risks of PRES and RCVS.

Contraindications and cautions

• Hypersensitivity to either active ingredient or an excipient
• Epilepsy
• Current MAOI treatment or use within the preceding two weeks
• Severe or uncontrolled hypertension, or treatment with antihypertensive therapy
• Severe acute or chronic kidney disease or renal failure

Monitoring

• Assess blood pressure and pulse where cardiovascular or sympathomimetic risk is relevant.
• Monitor for sedation, anticholinergic effects, urinary retention and CNS stimulation.
• Stop and assess urgently if neurological, acute visual, ischaemic bowel or severe pustular skin symptoms develop.

Clinical pharmacology

Pseudoephedrine has direct and indirect sympathomimetic activity and is largely excreted unchanged in urine. Chlorphenamine is an H1 antihistamine with sedating and anticholinergic effects; it is absorbed orally, extensively metabolised in the liver and excreted in urine.

Formulation and product differences

• The selected product is a prescription-only oral liquid.
• It contains ethanol, amaranth and sodium parahydroxybenzoates, which may cause allergic reactions; it is described as essentially sodium-free.
• It is supplied in an amber glass bottle and should be protected from light and stored below 25°C.