amitriptyline hydrochloride: clinical use

Prescribing considerations

• Assess suicide and overdose risk.
• Review cardiac disease, QT-prolonging medicines, electrolyte disturbance and anticholinergic burden.
• Use particular caution with epilepsy, urinary retention, prostatic enlargement, narrow-angle glaucoma, diabetes, hyperthyroidism, hepatic impairment and older age.
• Persistent childhood enuresis requires specialist expertise, exclusion of organic pathology and a pretreatment ECG.
• Avoid abrupt discontinuation after established use.

Contraindications and cautions

• Hypersensitivity to amitriptyline or a formulation excipient.
• Recent myocardial infarction, heart block, cardiac rhythm disorder or coronary insufficiency.
• Concurrent monoamine oxidase inhibitor treatment.
• Severe liver disease.
• Use for nocturnal enuresis in children younger than 6 years.

Monitoring

• Clinical response, adverse effects, suicidal thinking and behavioural change.
• Pulse, blood pressure and cardiac symptoms; consider ECG and electrolytes where cardiac risk is present.
• Anticholinergic effects, falls, cognition and postural hypotension, particularly in older adults.
• Blood glucose where diabetes is present.
• Serum sodium if symptoms suggest hyponatraemia.

Clinical pharmacology

A tertiary-amine tricyclic antidepressant that inhibits serotonin and noradrenaline reuptake and has anticholinergic, sedative and ion-channel-blocking properties. It is metabolised in the liver, including through CYP2D6 and CYP2C19, to active nortriptyline.

Formulation and product differences

• Selected products include film-coated tablets and oral solutions.
• The selected tablet contains lactose.
• Selected oral solutions contain methyl and propyl parahydroxybenzoate and require an appropriate oral measuring device.
• Concentration and excipients differ between oral solutions; identify the exact product clearly.

Oral solution

Route: Oral

Strengths: 10 mg/5 mL, 25 mg/5 mL, 50 mg/5 mL

Tablet

Route: Oral

Strengths: 10 mg, 25 mg, 50 mg