Ambroxol

Ambroxol is an oral mucolytic and secretolytic used for cough with viscous sputum. Evidence of clinical benefit is limited. It is the active metabolite of bromhexine.

Classification. Mucolytic, secretolytic, with local anaesthetic effect on the pharynx in lozenge form.

Mechanism. Stimulates serous secretion and surfactant production, lowers mucus viscosity and improves ciliary clearance.

Pharmacokinetics. Rapid absorption, bioavailability about 70 to 80%. Half-life about 10 hours. Hepatic metabolism by CYP3A4, renal excretion of metabolites.

Alternative, productive cough, adults and children over 12 years. 30 mg two to three times daily; after the first 2 to 3 days, 30 mg twice daily is usual. Maximum 120 mg daily. Slow-release 75 mg once daily.

Children. 6 to 12 years: 15 mg two to three times daily. 2 to 5 years: 7.5 mg three times daily. Under 2 years: 7.5 mg twice daily on clinical advice only.

Duration. Up to 7 days in acute illness, longer under review in chronic disease.

Emergency and specialist use. None. Loading and titration do not apply.

Contraindications. Hypersensitivity, rare hereditary fructose intolerance in some syrups.

Serious adverse effects. Anaphylaxis, severe cutaneous reactions (Stevens-Johnson syndrome, toxic epidermal necrolysis, acute generalised exanthematous pustulosis).

Common adverse effects. Nausea, dyspepsia, diarrhoea, mouth and throat numbness with lozenges.

Interactions. Raises antibiotic concentrations in lung tissue. Cough suppressants lead to secretion accumulation.

Common prescribing errors. Prescribing with a cough suppressant. Continuing after skin or mucosal changes.

Special groups.

• Pregnancy: avoid in the first trimester. Breastfeeding: passes into milk; avoid.

• Older adults: no adjustment.

• Kidney impairment: in severe impairment, reduce the dose or lengthen the interval. Liver impairment: same.

• East Africa: widely available and often combined in cough syrups. Cough over 2 weeks needs tuberculosis testing.

Formulations. Tablets 30 mg, slow-release capsules 75 mg, syrup 15 mg/5 mL and 30 mg/5 mL, lozenges.

Administration. Give after meals with water.

Baseline. Cough duration, red flags, history of skin reactions.

Monitoring. Sputum, cough, skin and mucosa.

Stop and reduce rules. Stop at the first skin or mucosal eruption. Stop if no benefit at 7 days. Therapeutic drug monitoring is not used.

Referral and escalation. Refer for cough over 2 weeks, haemoptysis, breathlessness or severe skin reaction.