guaifenesin + levomenthol: clinical use

Prescribing considerations

• Assess persistent or chronic cough, suspected asthma and cough with excessive secretions before recommending self-treatment.
• Use caution in severe hepatic or renal impairment; these groups have not been specifically studied.
• Account for glucose, sucrose, ethanol, sodium, sodium benzoate and colouring.

Contraindications and cautions

• Hypersensitivity to either active ingredient or any excipient.
• Children under 12 years.
• Hereditary fructose intolerance, glucose-galactose malabsorption or sucrase-isomaltase insufficiency.

Monitoring

• Review persistent or worsening cough, chest pain, breathing difficulty, systemic illness or haemoptysis.
• Monitor clinically for gastrointestinal intolerance and hypersensitivity; routine laboratory monitoring is not specified.
• Consider interference when interpreting urinary 5-HIAA or VMA measurements.

Clinical pharmacology

Guaifenesin is an expectorant thought to increase respiratory-tract fluid and reduce secretion viscosity through gastric-receptor and reflex pathways. It is absorbed gastrointestinally and undergoes oxidation and demethylation. Levomenthol is absorbed orally, hydroxylated in the liver, conjugated with glucuronide and excreted in urine and bile.

Formulation and product differences

• The selected product is a clear red, non-drowsy oral syrup.
• It contains glucose, sucrose, ethanol, sodium, sodium benzoate and Ponceau 4R; the colouring may cause allergic reactions.