diphenhydramine hydrochloride + paracetamol + pseudoephedrine hydrochloride: clinical use

Prescribing considerations

• Confirm that symptoms warrant a multi-ingredient product and check for duplicate paracetamol, diphenhydramine or sympathomimetic exposure.
• Assess cardiovascular, renal, hepatic, endocrine, ophthalmic and urinary history before supply.
• Consider sedative and antimuscarinic burden, particularly in older or frail people.
• Advise immediate discontinuation and assessment for symptoms suggesting PRES, RCVS, ischaemic colitis, ischaemic optic neuropathy or a serious skin reaction.
• Consider high-anion-gap metabolic acidosis in severely ill, malnourished, septic or glutathione-depleted patients receiving paracetamol, especially with flucloxacillin.

Contraindications and cautions

• Hypersensitivity to an active ingredient or excipient
• Cardiovascular disease, including hypertension
• Diabetes mellitus
• Phaeochromocytoma
• Hyperthyroidism
• Closed-angle glaucoma
• Severe acute or chronic kidney disease or renal failure
• Concurrent sympathomimetic decongestants, beta-blockers or MAO inhibitors, including recent MAO-inhibitor use

Monitoring

• Review blood pressure, pulse and cardiovascular symptoms where clinically indicated.
• Monitor for sedation, impaired psychomotor performance, confusion, hallucinations and antimuscarinic effects.
• Assess urinary retention risk in people with prostatic enlargement or voiding difficulty.
• Investigate sudden neurological, visual, abdominal or severe dermatological symptoms promptly.
• Review persistent or worsening symptoms rather than continuing unsupervised use.

Clinical pharmacology

Paracetamol has central analgesic and antipyretic activity. Pseudoephedrine is a directly and indirectly acting sympathomimetic decongestant, eliminated mainly in urine. Diphenhydramine is a centrally penetrating H1 antagonist with sedative and antimuscarinic properties and extensive first-pass metabolism.

Formulation and product differences

• The white daytime tablet contains paracetamol with pseudoephedrine.
• The blue film-coated night-time tablet contains paracetamol with diphenhydramine.
• The day and night tablets are not interchangeable because their active ingredients and effects differ.
• The blue tablet contains indigo carmine, titanium dioxide and propylene glycol in its film coating.
• The product is essentially sodium-free.