Makindo Medical Notes

🌙 Melatonin is a “body-clock” hormone used to help sleep onset and circadian timing. 🇬🇧 In the UK, the common licensed adult use is prolonged-release melatonin 2 mg for short-term primary insomnia in adults ≥55 (usually up to 13 weeks). Always check the BNF and follow local formulary rules (many ICBs restrict prescribing outside the licensed indication).

📘 About: Always check the BNF

• 📚 BNF: Melatonin
• ✅ Licensed adult insomnia use (UK): prolonged-release 2 mg in adults ≥55 for short-term primary insomnia.
• 👶 Paediatric use is often specialist-initiated and product-specific (e.g. ASD/ADHD pathways); dosing and licensing depend on formulation.

⚙️ Mode of action

• 🕰️ Acts on MT1/MT2 receptors in the suprachiasmatic nucleus → helps sleep initiation and circadian alignment.
• 🧩 Particularly helpful when insomnia is driven by circadian delay (late sleep onset) rather than pain/breathlessness/delirium.
• 💊 Prolonged-release preparations aim to mimic the body’s overnight melatonin profile.

✅ Indications (common UK practice)

• 🌙 Primary insomnia in adults ≥55 (licensed, short-term).
• ✈️ Jet lag / circadian rhythm disturbance (use is formulation-dependent; follow BNF/local guidance).
• 👶 Neurodevelopmental insomnia (e.g. ASD/ADHD): usually specialist-led with strict sleep-hygiene prerequisites and review plans.

💊 Dose range: short-term use (adult insomnia ≥55)

🔁 Review early: if no meaningful benefit after ~3 weeks (or local policy), stop rather than continuing indefinitely. If it helps, keep within the intended short-term course unless specialist advice supports longer.

🔗 Interactions (high-yield)

• 🚫 Fluvoxamine: can markedly increase melatonin exposure — avoid (BNF lists as severe).
• 🧪 CYP1A2 inhibitors (e.g. ciprofloxacin, oestrogens) may increase melatonin levels → more next-day drowsiness.
• 🩸 Warfarin/anticoagulants: possible INR effect — monitor INR if co-prescribed.
• 😴 Additive sedation with benzodiazepines, Z-drugs, opioids, antihistamines, alcohol.

⚠️ Cautions

• 🧓 Older adults: falls risk if morning grogginess, dizziness, or nocturia worsens — start when they can trial safely.
• 🫘 Hepatic impairment: exposure may be higher (check BNF; consider avoiding in severe liver disease).
• 🧠 Epilepsy: rare reports of increased seizure activity — use specialist advice if relevant.
• 🤰 Pregnancy/breastfeeding: avoid unless specialist recommendation (limited safety data).

⛔ Contraindications

• 📚 Product-specific — see BNF and local formulary.
• ⚠️ Practical “contraindication”: unaddressed causes of poor sleep (pain, nocturia, OSA, depression, delirium, stimulants) — fix these first.

😵 Side effects

• 🤕 Headache, dizziness, nausea.
• 😴 Somnolence / next-day drowsiness, vivid dreams.
• 🦴 Occasional: joint pain, fatigue, irritability.

🩺 Practical prescribing tips

• 🧼 Always pair with sleep hygiene (light exposure in the morning, consistent wake time, minimise late caffeine/screens).
• 🕰️ If the problem is sleep phase delay, timing matters more than dose — take it earlier, not higher.
• 🧾 Document: indication, formulation (IR vs MR), start date, review date, and stop plan.

📖 References

• BNF – Melatonin
• NICE CKS – Prolonged-release melatonin (insomnia)

🛠️ Revisions