Melatonin: Drug Information
1. Drug Name
Generic Name
Melatonin
Brand Name(s)
- Pakistan: BrandX
- India: BrandY
- US: BrandZ
- UK: BrandW
2. Pharmacological Class
Class
Hormone
Subclass
Endogenous melatonin receptor agonist
3. Mechanism of Action
Melatonin is a hormone primarily synthesized by the pineal gland in the brain. It regulates sleep-wake cycles (circadian rhythms) and has other effects on the body. Melatonin acts mainly through binding to melatonin receptors in the brain, particularly MT1 and MT2 receptors, which are involved in the control of the sleep-wake cycle.
4. Indications
Primary Indications
- Insomnia, particularly for circadian rhythm disorders and jet lag
- Supplemental treatment in sleep disorders in children with neurodevelopmental disorders (e.g., autism, ADHD)
Off-label Uses
- Adjustment of sleep-wake cycle in shift workers
- Adjunctive treatment in migraine prevention
5. Dosage and Administration
Standard Dosage
The dosage of melatonin varies depending on the condition being treated and the age of the patient. Consult with a healthcare provider for specific dosing.
Route of Administration
Melatonin is commonly administered orally as tablets, capsules, or liquid formulations.
Special Populations
- Pediatric: Consult with a healthcare provider for appropriate dosing in children.
- Geriatric: Start with lower doses due to potential sensitivity.
6. Pharmacokinetics
Absorption
Melatonin is absorbed quickly and completely from the gastrointestinal tract.
Distribution
It crosses the blood-brain barrier and enters all body tissues.
Metabolism
Melatonin is metabolized primarily in the liver by CYP1A2 and excreted via urine.
Excretion
Excreted mainly via urine.
Half-life
The elimination half-life varies widely but is generally between 20 and 50 minutes.
7. Contraindications
Melatonin is contraindicated in individuals with hypersensitivity to melatonin or any component of the formulation.
8. Warnings and Precautions
- May cause drowsiness; avoid driving or operating machinery within 5 hours of taking melatonin.
- Use caution in individuals with a history of depression or other psychiatric disorders.
- Do not use in pregnant or breastfeeding women without consulting a healthcare provider.
9. Side Effects
Common Side Effects
- Drowsiness
- Headache
- Nausea
Serious Side Effects
- Severe allergic reactions are rare but possible.
- Long-term effects of melatonin supplements are not well-understood.
10. Drug Interactions
Major Interactions
- Anticoagulants (blood thinners)
- Anticonvulsants (seizure medications)
Moderate Interactions
- Immunosuppressants
- Diabetes medications
Minor Interactions
- Caffeine
- Alcohol
11. Pregnancy and Lactation
Pregnancy Category
Category C - Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.
Breastfeeding Considerations
It is not known whether melatonin is excreted in human milk; use with caution.
12. Patient Counseling Information
- Take melatonin approximately 30 minutes before bedtime for insomnia.
- Avoid bright lights and stimulants (like caffeine) before bedtime.
- Discuss with healthcare provider before starting melatonin, especially if pregnant, breastfeeding, or taking other medications.