Melatonin

# Melatonin ## Overview - **Classification**: Endogenous neurohormone, Chronobiotic. - **Mechanism**: Primarily regulates circadian rhythms and sleep-wake cycles by acting on MT1 and MT2 receptors in the suprachiasmatic nucleus. Signals "darkness" to the body. ## Primary Indications 1. **Insomnia (Sleep Onset)** - Difficulty falling asleep. 2. **Jet Lag** - Resynchronizing sleep-wake cycles after rapid time zone changes. 3. **Sleep-Wake Cycle Disturbances** - Especially in children/adolescents with neurodevelopmental disorders (e.g., ASD, ADHD). ## Adult Dosing ### Standard Dosing **Insomnia (Sleep Onset)** - **Dose**: **0.5 mg** to **5 mg** - **Frequency**: Once daily, 30-60 minutes before bedtime - **Route**: Oral - **Duration**: Short-term; adjust based on clinical need **Jet Lag** - **Dose**: **0.5 mg** to **5 mg** - **Frequency**: Once daily, 30-60 minutes before desired bedtime at destination - **Route**: Oral - **Duration**: For 2-5 nights ### Dose Adjustments - **Renal Impairment**: No specific adjustment required. - **Hepatic Impairment**: No specific adjustment required. Use with caution. - **Elderly Patients**: May be more sensitive; consider starting at **0.5 mg**. ## Pediatric Dosing *Note: Use in children is generally off-label unless for specific conditions like neurodevelopmental disorders.* ### Neonates (0-28 days) - **Special Notes**: Not recommended due to lack of safety and efficacy data. ### Infants (1-12 months) - **Dose**: **0.5 mg** to **1 mg** - **Frequency**: Once daily, 30-60 minutes before bedtime - **Maximum**: **1 mg** - **Special Notes**: Limited data; use with extreme caution and medical supervision. ### Children (1-12 years) - **Indication**: Sleep onset insomnia, esp. with neurodevelopmental disorders. - **Dose**: Start with **1 mg** to **3 mg** - **Frequency**: Once daily, 30-60 minutes before bedtime - **Maximum**: **5 mg** (up to **10 mg** for severe cases in special populations, with physician guidance) - **Special Notes**: Start low, titrate slowly. Encourage good sleep hygiene. ### Adolescents (13-18 years) - **Indication**: Sleep onset insomnia, jet lag. - **Dose**: Start with **1 mg** to **3 mg** - **Frequency**: Once daily, 30-60 minutes before bedtime - **Maximum**: **5 mg** (up to **10 mg** for specific cases) ## Safety Information ### Contraindications - **Absolute**: None universally accepted. - **Relative**: Autoimmune diseases (potential immune modulation), pregnancy/lactation (lack of data). ### Common Adverse Effects - **Common (1-10%)**: Drowsiness, headache, dizziness, nausea. - **Less Common (<1%)**: Mild abdominal cramps, vivid dreams/nightmares, irritability. - **Serious but Rare**: Allergic reactions, paradoxical effects (worsening insomnia). ### Key Drug Interactions - **Anticoagulants (e.g., Warfarin)**: Potential increased bleeding risk. Monitor INR. - **CNS Depressants (e.g., Benzodiazepines, Alcohol)**: Increased sedation. Avoid concurrent use. - **Fluvoxamine**: Significantly increases melatonin levels (CYP1A2 inhibitor). Avoid co-administration. - **Nifedipine**: May decrease blood pressure. Monitor BP. - **CYP1A2 Inducers (e.g., Rifampin, Carbamazepine)**: May decrease melatonin efficacy. ## Monitoring & Follow-up - **Before Treatment**: Assess sleep hygiene, rule out underlying medical conditions. - **During Treatment**: Monitor for desired sleep effect, daytime somnolence, headache, GI upset. - **Clinical Signs**: Improvement in sleep latency, sleep quality, and daytime functioning. ## Clinical Pearls - 💡 **Dosing Variability**: Optimal dose varies widely; "less is often more." Start with the lowest effective dose. - 💡 **Timing is Key**: Take 30-60 minutes *before* desired sleep time for best effect on sleep onset. - 💡 **Not a Hypnotic**: Melatonin is not a sedative; it signals the body it's time to sleep rather than forcing sleep. - 💡 **Formulation Differences**: OTC melatonin products can vary significantly in actual melatonin content. - 💡 **Adjunct, Not Replacement**: Best used as an adjunct to good sleep hygiene practices. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.