Hetlioz (Tasimelteon)

Hetlioz is prescribed to help patients whose internal biological clock is out of sync with the 24‑hour day, particularly those with non‑24‑hour sleep‑wake disorder.

• Improves alignment of sleep‑wake cycles with the external light‑dark schedule
• Reduces daytime sleepiness and nighttime insomnia associated with Non‑24
• Used as part of a comprehensive management plan that may include light therapy and behavioral strategies
• Typically initiated after confirming diagnosis of Non‑24 through clinical assessment and sleep‑wake pattern monitoring

• Tasimelteon selectively activates the melatonin MT1 and MT2 receptors located in the suprachiasmatic nucleus, the master circadian pacemaker. By mimicking the action of endogenous melatonin, it promotes phase‑shifting of the circadian clock, facilitating entrainment of the sleep‑wake cycle to the 24‑hour environment. This receptor agonism helps synchronize physiological rhythms without directly inducing sedation. The drug’s high affinity for both receptor subtypes ensures a balanced activation that supports both sleep onset and maintenance.

Common and serious adverse reactions have been reported with Hetlioz; most are mild and transient.

Common

• Headache
• Nausea
• Fatigue
• Dizziness
• Transient insomnia
• Mild somnolence

Serious

• Severe allergic reaction (e.g., rash, swelling, difficulty breathing)
• Suicidal thoughts or behavior
• Significant elevation of liver enzymes
• Visual disturbances such as blurred vision

Before starting Hetlioz, certain precautions should be considered to ensure safe use.

• Pregnancy safety has not been established; use only if the potential benefit justifies the potential risk.
• Use caution in patients with hepatic impairment; dose adjustment may be required.
• Monitor for mood changes, including depression or suicidal ideation.
• Assess for any history of allergic reactions to melatonin receptor agonists.
• Evaluate concurrent use of CNS depressants that may increase sedation.
• Not recommended for children unless specifically indicated by a specialist.

Hetlioz may interact with other medications that affect melatonin pathways or hepatic metabolism.

Avoid

• Strong CYP1A2 inhibitors (e.g., fluvoxamine) that can increase tasimelteon plasma concentrations.
• Concurrent use of other melatonin receptor agonists (e.g., ramelteon) due to additive pharmacologic effects.

Use with caution

• CYP1A2 substrate drugs (e.g., theophylline) as tasimelteon may alter their metabolism.
• Central nervous system depressants (e.g., benzodiazepines, barbiturates) because of potential enhanced sedation.
• Alcohol consumption, which may potentiate CNS effects.
• Medications that prolong QT interval; monitor cardiac status if combined.