Melatonin Viatris (Melatonin)

Melatonin acts on the melatonin receptor pathway to support normal sleep regulation. It is indicated for the following conditions:

• Insomnia: helps reduce time to fall asleep and improve sleep quality.
• Circadian rhythm sleep‑wake disorders: assists in realigning the internal clock for shift‑work or delayed sleep phase.
• Jet lag: facilitates faster adaptation to new time zones after long‑distance travel.

• Melatonin binds to MT1 and MT2 receptors in the suprachiasmatic nucleus, mimicking endogenous melatonin. This activation modulates the circadian signaling cascade, decreasing neuronal firing that promotes wakefulness and enhancing signals that favor sleep onset, thereby helping to synchronize the sleep‑wake cycle.

Melatonin is generally well tolerated, but adverse reactions can occur.

Common Side Effects

• Headache: mild to moderate pain often resolving without intervention.
• Dizziness: transient sensation of light‑headedness.
• Daytime sleepiness: occasional residual drowsiness after dosing.
• Nausea: mild gastrointestinal discomfort.
• Vivid dreams: unusual or intense dreaming patterns.
• Mild gastrointestinal upset: stomach discomfort or mild diarrhea.

Serious or Rare Side Effects

• Allergic reactions: rash, itching, swelling, or anaphylaxis.
• Severe mood changes: depression, irritability, or agitation.
• Hallucinations: visual or auditory disturbances.
• Severe hypotension: marked drop in blood pressure leading to faintness.
• Respiratory difficulty: shortness of breath or wheezing.

When considering melatonin therapy, several safety measures are recommended.

• Assess underlying sleep disorder: confirm diagnosis before initiating therapy.
• Review concomitant medications: identify agents that may increase sedation or affect melatonin metabolism.
• Use lowest effective dose: start with the smallest dose that provides benefit.
• Avoid operating machinery: refrain from driving or hazardous tasks if residual sleepiness occurs.
• Monitor for allergic reactions: discontinue if rash, swelling, or breathing difficulty develop.
• Store at room temperature: keep in the original container, protect from moisture and direct sunlight.

Melatonin may interact with other medicines, requiring attention to potential additive effects.

Major Interactions (Avoid)

• CNS depressants (e.g., benzodiazepines, alcohol): additive sedation may impair alertness.
• Anticoagulants (e.g., warfarin): possible increase in bleeding risk.

Moderate Interactions (Monitor Closely):\n- CYP1A2 inhibitors (e.g., fluvoxamine): elevated melatonin plasma levels.

• Antidiabetic agents: potential alteration of glucose control.
• Oral contraceptives: may raise circulating melatonin concentrations.