Solriamfetol (Sunosi), a new dopamine and norepinephrine reuptake inhibitor (DNRI), has been approved by the FDA “to improve wakefulness in adult patients with excessive daytime sleepiness associated with narcolepsy or obstructive sleep apnea.” The medication has never been studied in psychiatry, but is likely to have important psychiatric effects.
How effective is it?
Approval was based on four studies of over 900 adults. In a randomized double-blind controlled trial of 239 adults with narcolepsy, 150 mg/day of Sunosi (but not 75 mg/day) showed statistically significant improvements in both objective (the Maintenance of Wakefulness Test) and subjective (the Epworth Sleepiness Scale) measures of sleepiness. In a similar study of 476 adults with sleep apnea, patients showed significant improvement on measures of sleepiness at 3 doses: 37.5 mg/day, 75 mg/day, and 150 mg/day. Both studies lasted 12 weeks, and the gains held up in two open-label maintenance studies that lasted up to 50 weeks.
What are the side effects?
About 1 in 25 people had at least one psychiatric side effect: anxiety, irritability, or insomnia. Based on its mechanism of action, psychosis and mania are potential risks, but we don’t know how serious those problems are since solriamfetol has not been studied in psychiatric populations. The most common physical side effects were headache, nausea, and low appetite. Solriamfetol also raises blood pressure and pulse in a dose-dependent manner. It should be avoided with monoamine oxidase inhibitors (MAOIs) because taking them together can raise the risk of hypertensive crisis.
Does solriamfetol have an abuse potential?
Solriamfetol has an abuse potential that was documented in a study of people with a history of recreational stimulant and polydrug abuse. Compared to phenteramine, it produced similar elevations of mood, relaxation, and “drug liking.” However, this only appeared to be a problem at doses higher than recommended (300–1200 mg). At lower doses, subjects found that solriamfetol’s aversive effects outweighed its reinforcing effects. The FDA plans to classify solriamfetol as a controlled substance but has not released the exact schedule yet (Carter LP, J Psychopharmacol 2018;32:1351–1361).
How will it be prescribed?
Sunosi will be available as scored 75 mg tablets and 150 mg tablets. Starting dose is 75 mg QAM for patients with narcolepsy and 37.5 mg QAM for patients with sleep apnea. Dose may be increased at intervals of at least 3 days; maximum dose is 150 mg/day. The half-life of Sunosi is approximately 7 hours. Sunosi is metabolized renally rather than hepatically; dose adjustments are recommended in renal impairment.
What is the cost?
Sunosi pricing is not available, and the drug is not yet available in pharmacies.
Solriamfetol joins modafinil (Provigil) and armodafinil (Nuvigil) as the only wakefulness-promoting agents with approval in both narcolepsy and obstructive sleep apnea. As a DNRI, its mechanism shares some overlap with other psychotropics, including modafinil, traditional stimulants, and bupropion. However, its profile is unique, and we’ll need to watch carefully when psychiatric patients start solriamfetol for narcolepsy or sleep apnea.
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