guaifenesin + paracetamol + phenylephrine hydrochloride: clinical use

Prescribing considerations

• Confirm that pain or fever, nasal congestion and productive cough coexist; narrower symptoms may expose patients to unnecessary active ingredients.
• Reconcile all products for duplicate paracetamol, sympathomimetics and cough suppressants.
• Assess hepatic and renal function, alcohol use, cardiovascular risk, blood pressure, thyroid disease, diabetes, glaucoma, prostatic symptoms and Raynaud's phenomenon.
• Persistent, recurrent or unusually productive cough warrants assessment.

Contraindications and cautions

• Hypersensitivity to an active substance or excipient
• Hypertension, hyperthyroidism, severe coronary or cardiovascular disease
• Current or recent monoamine oxidase inhibitor therapy
• Concurrent sympathomimetic decongestants
• Phaeochromocytoma, closed-angle glaucoma, diabetes mellitus or prostatic enlargement in selected products
• Contraindications differ between products; hepatic or severe renal impairment and certain cardiovascular medicines are additionally listed for some tablet formulations.

Monitoring

• No routine laboratory monitoring is specified for uncomplicated label-directed use.
• Review blood pressure, pulse, urinary symptoms and cardiovascular adverse effects when clinically relevant.
• In severe illness, renal impairment, sepsis, malnutrition, chronic alcohol misuse or concurrent flucloxacillin, investigate unexplained high-anion-gap metabolic acidosis and stop paracetamol if suspected.
• Guaifenesin metabolites can interfere with urinary 5-HIAA and VMA testing; inform the laboratory about recent use.

Clinical pharmacology

Paracetamol provides central analgesic and antipyretic activity. Oral phenylephrine undergoes substantial first-pass metabolism and acts as an alpha-adrenergic vasoconstrictor. Guaifenesin is absorbed gastrointestinally, metabolised and excreted in urine; selected product information notes that it may increase paracetamol absorption.

Formulation and product differences

• Selected products include capsules, film-coated tablets and powder for oral solution, with different ingredient strengths and minimum ages.
• Capsules and tablets are swallowed whole; powders require dissolution in water.
• Selected powder contains sucrose, lactose, aspartame and a clinically relevant sodium load; it may be unsuitable for phenylketonuria, certain rare sugar disorders or sodium restriction.
• Selected capsules are essentially sodium-free.
• Use the contraindications, excipient information and instructions for the exact marketed pack.

Capsule

Route: Oral

Strengths: 500 mg + 100 mg + 6.1 mg

Oral solution

Route: Oral

Strengths: 1000 mg + 200 mg + 12.2 mg