melatonin: clinical use

Prescribing considerations

• Confirm the specific product, formulation and indication; melatonin products are not automatically interchangeable.
• Paediatric ADHD-related insomnia and delayed sleep–wake phase indications require relevant specialist expertise and prior attention to sleep hygiene.
• Assess daytime sedation, driving or occupational risk, alcohol use, smoking, epilepsy, autoimmune disease, glucose intolerance and hepatic or renal impairment.
• Switching formulations can materially change exposure and somnolence risk.

Contraindications and cautions

• Hypersensitivity to melatonin or a formulation excipient.
• Check product-specific excipients and restrictions, including lactose or liquid excipients.

Monitoring

• Review clinical benefit, daytime alertness and neuropsychiatric adverse effects.
• In paediatric treatment, periodically reassess whether melatonin remains appropriate.
• Consider glucose monitoring in diabetes or impaired glucose tolerance.
• Review anticoagulant control when clinically appropriate in patients taking warfarin.
• During breastfeeding, monitor the infant for drowsiness and ineffective feeding.

Clinical pharmacology

Melatonin acts mainly at MT1 and MT2 receptors. Oral bioavailability is limited by first-pass metabolism, predominantly involving CYP1A2; absorption and peak exposure vary substantially between immediate-release, prolonged-release and liquid formulations.

Formulation and product differences

• Prolonged-release tablets must generally be swallowed whole to preserve modified release.
• Mellozzan immediate-release tablets may be crushed and mixed with water immediately before use.
• Hard capsules are swallowed whole.
• Oral solutions may produce different systemic exposure from tablets; use the supplied measuring device.
• Food requirements and excipients differ between products.

Capsule

Route: Oral

Strengths: 2 mg, 3 mg, 5 mg

Modified-release tablet

Route: Oral

Strengths: 1 mg, 2 mg, 5 mg