Ramelteon

Indications

• FDA-approved for the treatment of insomnia characterized by difficulty with sleep onset in adults, with no limit on treatment duration.
• It is the preferred hypnotic when a patient has a substance use disorder, since it is not a controlled substance and shows no abuse liability.
• The American Academy of Sleep Medicine gives it a weak recommendation for sleep-onset insomnia based on small but consistent latency reductions.
• Off-label for circadian rhythm disorders such as delayed sleep-wake phase and non-24-hour sleep-wake disorder in some practice settings.
• Off-label for delirium prevention in hospitalized older adults, supported by a randomized trial showing reduced delirium incidence.
• It does not meaningfully improve sleep maintenance or total sleep time, so it is a poor choice for middle-of-the-night awakening.

Mechanism of action

• Potent selective agonist at melatonin MT1 and MT2 receptors in the suprachiasmatic nucleus, with no measurable affinity for GABA-A receptors.
• MT1 activation attenuates the circadian wake-promoting signal of the suprachiasmatic nucleus, which shortens time to sleep onset.
• MT2 activation shifts circadian phase, providing the rationale for use in delayed sleep-wake phase and shift work disorder.
• Because it does not act on GABA-A, it produces no muscle relaxation, no anticonvulsant effect, no amnesia and no reinforcement.
• The absence of GABAergic action explains why abrupt discontinuation causes neither rebound insomnia nor a withdrawal syndrome.

Pharmacokinetics

• Absorbed rapidly with peak levels near 45 minutes, but absolute bioavailability is only about 1.8 percent due to extensive first-pass metabolism.
• Parent half-life is 1-2.6 hours; the active metabolite M-II has a 2-5 hour half-life and circulates at 20-100 times parent concentration.
• Oxidized principally by CYP1A2, with minor contributions from CYP2C and CYP3A4, then glucuronidated and excreted mostly in urine.
• A high-fat meal delays the peak by about 45 minutes and raises total exposure, so avoid dosing with or right after a heavy meal.
• Exposure roughly doubles in mild to moderate hepatic impairment and rises much further in severe disease, where it is contraindicated.

Dosing

• Adults: 8 mg PO within 30 minutes of bedtime; this is both the recommended and the maximum dose, and higher doses add nothing.
• Do not take with or immediately after a high-fat meal, since delayed absorption undercuts the sleep-onset effect.
• No dose adjustment is required for older adults, though exposure is somewhat higher and effect may be modestly greater.
• Use with caution in mild to moderate hepatic impairment; ramelteon is contraindicated in severe hepatic impairment.
• No dose adjustment is needed at any degree of renal impairment, including patients on chronic hemodialysis.
• No taper is required on discontinuation, since ramelteon causes neither physical dependence nor rebound insomnia.

Adverse effects

• Somnolence in about 5 percent, dizziness 5 percent, fatigue 4 percent, nausea 3 percent, and worsened insomnia in about 3 percent.
• Effect size is modest, reducing subjective sleep latency by roughly 10-15 minutes, and many patients judge it insufficient.
• Endocrine changes including decreased testosterone and increased prolactin, with reports of amenorrhea, galactorrhea and reduced libido.
• Complex sleep behaviors, hallucinations and abnormal thinking have been reported in postmarketing use, though there is no boxed warning.
• Anaphylaxis and angioedema, including tongue and throat swelling, can occur after the first dose and preclude any rechallenge.
• Worsening depression and suicidal ideation have been reported; monitor patients with a history of mood disorder after starting.

Monitoring

• Reassess sleep latency and total sleep time after 7-10 nights; failure to improve should prompt evaluation for a comorbid disorder.
• Check prolactin and testosterone if amenorrhea, galactorrhea, decreased libido or fertility problems emerge during therapy.
• Assess for depression and suicidal ideation at follow-up, since worsening mood has been reported with hypnotic therapy generally.
• Screen for and treat obstructive sleep apnea, restless legs, alcohol use and untreated mood disorder before or alongside treatment.
• No routine laboratory monitoring is otherwise required, and no prescription monitoring program check is needed since it is not scheduled.

Interactions

• Concurrent fluvoxamine is contraindicated; strong CYP1A2 inhibition raises ramelteon exposure roughly 190-fold and produces marked sedation.
• Other CYP1A2 inhibitors including ciprofloxacin and cimetidine raise levels meaningfully and should be combined only with caution.
• Rifampin and other strong inducers reduce exposure by about 80 percent and can abolish any clinical benefit.
• Fluconazole and ketoconazole increase exposure modestly through CYP2C9 and CYP3A4 inhibition; monitor for excess sedation.
• Alcohol produces additive psychomotor impairment; also contraindicated in patients with a history of angioedema on ramelteon.

Special populations

• Pregnancy: human data are insufficient; animal studies showed developmental toxicity at high doses, so use only if clearly needed.
• Lactation: it is not known whether ramelteon is excreted in human milk, so monitor the nursing infant for sedation and poor feeding.
• Pediatrics: safety and effectiveness are not established under age 18, and pediatric trials in neurodevelopmental disorders were negative.
• Older adults: not flagged for avoidance by the AGS Beers Criteria, unlike benzodiazepines and Z-drugs, making it a reasonable geriatric option.
• Hepatic impairment: contraindicated in severe disease and used cautiously in mild to moderate; no renal adjustment is required.

Clinical pearls

• Not a controlled substance and not habit forming, so it is the hypnotic of choice in addiction.
• Fluvoxamine is an absolute contraindication; it raises ramelteon levels roughly 190-fold.
• Real effect is about 10-15 minutes of sleep latency, so set expectations before prescribing.