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NERVOUS SYSTEM › PSYCHOLEPTICS › HYPNOTICS AND SEDATIVES › Melatonin receptor agonists
melatonin
N05CH01
Forms & Strengths
- Oral tablet: 1 mg, 3 mg, 5 mg, 10 mg
- Oral capsule: 3 mg, 5 mg
- Oral liquid: 1 mg/4 mL, 1 mg/10 mL
- Sublingual tablet: 1 mg, 3 mg, 5 mg
- Extended-release tablet: 2 mg, 3 mg
Adult Dosing
- Insomnia: 1 mg to 10 mg orally once daily 30-60 minutes before bedtime
- Jet lag: 0.5 mg to 5 mg orally once daily at bedtime on the day of arrival at destination, continuing for 2-5 days
- Circadian rhythm sleep disorders: 0.5 mg to 3 mg orally once daily timed appropriately to phase-shift
Pediatric Dosing
- Insomnia (autism spectrum disorder or neurogenetic conditions): 0.5 mg to 6 mg orally once daily at bedtime
- Initial dose: 1 mg to 3 mg 30-60 minutes before bedtime, titrated up by 1 mg weekly to max 6-10 mg
- Safety and efficacy in infants under 2 years are not well established
Indications
- Short-term treatment of primary insomnia
- Sleep disturbances secondary to circadian rhythm disorders (e.g., jet lag, shift work)
- Sleep difficulties in children and adolescents with neurodevelopmental disorders
Mechanism of Action
- Agonist at high-affinity melatonin MT1 and MT2 receptors in the suprachiasmatic nucleus of the hypothalamus
- Regulates circadian rhythms and promotes sleep onset by inhibiting the wake-promoting signals of the circadian pacemaker
Contraindications
- Hypersensitivity to melatonin or any component of the formulation
- Severe hepatic impairment (relative contraindication due to significantly reduced clearance)
Adverse Reactions
- Common: Headache, dizziness, nausea, somnolence, vivid dreams
- Less common: Irritability, mild anxiety, transient depressive symptoms, abdominal cramps, orthostatic hypotension
- Rare: Pruritus, rash, elevated liver enzymes
Drug Interactions
- CYP1A2 inhibitors (e.g., fluvoxamine, ciprofloxacin) increase melatonin plasma concentrations and systemic exposure
- CYP1A2 inducers (e.g., carbamazepine, rifampin) decrease melatonin concentrations
- CNS depressants (e.g., ethanol, benzodiazepines, opioids) may enhance sedative and psychomotor adverse effects
- Anticoagulants/Antiplatelets may theoretically increase bleeding risk, though clinical significance is variable
Curated Content: Needs Vetting Before Put to Clinical Use