Hetlioz (Tasimelteon)

Hetlioz is prescribed primarily for adults with non‑24‑hour sleep‑wake disorder (Non‑24), a condition most commonly seen in individuals who are completely blind.

• Aligns the internal circadian clock with the 24‑hour day, reducing misaligned sleep episodes.
• Increases consistency of nighttime sleep duration and improves overall sleep quality.
• Used alongside behavioral sleep‑hygiene measures as part of a broader treatment plan.
• Considered when standard melatonin supplementation does not adequately entrain the sleep‑wake cycle.
• Prescribed after clinical confirmation of non‑24‑hour sleep‑wake disorder by a qualified provider.

• Tasimelteon is a selective agonist of the melatonin MT1 and MT2 receptors located in the suprachiasmatic nucleus of the hypothalamus. By binding to these G‑protein‑coupled receptors, the drug mimics the action of endogenous melatonin, promoting phase‑shifting and entrainment of the central circadian pacemaker to the external 24‑hour light‑dark cycle. This receptor activation helps synchronize physiological rhythms, facilitating a more regular sleep‑wake pattern.

Adverse reactions to Hetlioz have been reported in clinical studies and post‑marketing surveillance. The frequency and severity of these events vary among individuals.

Common

• Headache, often mild to moderate and may improve with continued therapy.
• Nausea or stomach discomfort, usually transient and may lessen after several doses.
• Fatigue or increased drowsiness, particularly after the initial dose, which often diminishes over time.
• Dizziness or light‑headed feeling, generally mild and self‑limiting.
• Insomnia or difficulty staying asleep, reported occasionally.

Serious

• Severe allergic reaction, including anaphylaxis, angioedema, or rash with swelling, requiring immediate medical attention.
• Mood alterations such as depression, anxiety, or emergence of suicidal thoughts, which should be reported promptly.
• Significant liver enzyme elevations that may indicate hepatic injury, warranting laboratory monitoring and possible discontinuation.
• Cardiovascular events such as palpitations or irregular heartbeat, which may require cardiac evaluation.

Before initiating Hetlioz, healthcare providers should evaluate several clinical factors to ensure safe use.

• Confirm diagnosis of non‑24‑hour sleep‑wake disorder through appropriate clinical assessment.
• Assess liver function, as hepatic impairment may affect drug metabolism.
• Use caution in patients with a history of depression, suicidal ideation, or other mood disorders.
• Avoid initiating therapy in individuals with known hypersensitivity to tasimelteon or any tablet excipients.
• Consider potential interactions with strong CYP1A2 inhibitors, which can increase tasimelteon exposure.
• Pregnancy and breastfeeding status should be reviewed; safety data are limited.

Hetlioz may interact with other medicines that influence its metabolism or affect melatonin pathways.

Avoid

• Concurrent use of strong CYP1A2 inhibitors (e.g., fluvoxamine, ciprofloxacin) which can markedly increase tasimelteon plasma levels.
• Co‑administration with other melatonin receptor agonists, as additive effects on circadian regulation are not established.

Use with caution

• Moderate CYP1A2 inhibitors (e.g., amiodarone, cimetidine) may modestly raise tasimelteon exposure; monitor for adverse effects.
• CYP1A2 inducers (e.g., smoking, rifampin) could reduce drug effectiveness; dose adjustment may be needed.
• Drugs that prolong QT interval should be used cautiously, as tasimelteon has a low but potential risk of cardiac effects.
• Alcohol consumption may enhance drowsiness; advise patients to limit intake.