Solriamfetol

• Narcolepsy
• Obstructive Sleep Apnea
• Excessive Daytime Sleepiness

Solriamfetol (brand name Sunosi) is a dopamine and norepinephrine reuptake inhibitor (DNRI) approved to improve wakefulness in adults with excessive daytime sleepiness associated with narcolepsy or obstructive sleep apnea. Unlike traditional amphetamine-class stimulants, it does not promote release of catecholamines, which contributes to a relatively favorable abuse-liability profile, although it remains a Schedule IV controlled substance. It is one of several wake-promoting agents now available, and its place in therapy continues to evolve as clinicians and patients gain experience.

Mechanism of Action

Solriamfetol blocks the dopamine transporter (DAT) and the norepinephrine transporter (NET), increasing synaptic concentrations of both monoamines in wake-promoting brain circuits including the locus coeruleus and the ventral tegmental area. Because it does not act as a substrate for these transporters, it does not trigger reverse transport and the surge of synaptic monoamines characteristic of amphetamines and methamphetamine. The result is increased and sustained alertness with less euphoria, less rebound, and minimal effect on sleep architecture when taken in the morning. The half-life of approximately 7 hours and slow onset relative to amphetamines further reduce the abuse potential. Solriamfetol has minimal metabolism through cytochrome P450 enzymes and is cleared predominantly unchanged by the kidneys, which simplifies drug interactions but mandates renal-based dose adjustment. It does not bind muscarinic, histaminergic, or serotonergic receptors at therapeutic concentrations, which translates into a relatively clean side-effect profile beyond the cardiovascular and psychiatric effects expected from catecholaminergic enhancement. The NHLBI overview of sleep apnea describes the underlying disorder.

Clinical Use

For obstructive sleep apnea, solriamfetol is an adjunct to and never a substitute for primary airway therapy such as CPAP, oral appliances, or surgical management; treating residual sleepiness without addressing apnea leaves cardiovascular and metabolic risk unmodified, including elevated stroke and heart failure risk. Studies have specifically required documented adherence to primary OSA therapy before enrollment. For narcolepsy, it is one of several wake-promoting agents that include modafinil, armodafinil, pitolisant, and traditional stimulants such as methylphenidate or lisdexamfetamine. Solriamfetol is often selected when modafinil has not produced adequate alertness, when modafinil's interactions with hormonal contraceptives are problematic, or when traditional stimulants have caused intolerable cardiovascular or psychiatric side effects. It does not treat cataplexy, the sudden loss of muscle tone often seen in type 1 narcolepsy; sodium oxybate or pitolisant are preferred when cataplexy is a major feature. For broader context, our articles on sleep apnea diagnosis and sleep hygiene cover the lifestyle and diagnostic foundations of treatment.

How to Take It

Solriamfetol is taken once daily upon awakening, with or without food, although a heavy meal may modestly delay onset. For narcolepsy, the starting dose is 75 mg with the option to double to 150 mg after at least three days based on response. For obstructive sleep apnea, the starting dose is typically 37.5 mg with weekly doubling to a maximum of 150 mg, allowing time for blood pressure and heart rate to acclimate. Avoid taking the medication within nine hours of planned bedtime to limit insomnia, which is a common dose-related adverse effect. Most patients notice the alerting effect within one to two hours of dosing, with effect lasting most of the day. If a dose is missed and bedtime is more than nine hours away, take it as soon as possible; otherwise, skip and resume the next morning. Storage is at room temperature in the original container; this is a controlled substance, so secure storage matters, particularly in households with adolescents or visitors. Do not crush or split tablets; the 37.5 mg formulation is provided specifically for OSA titration.

Monitoring and Follow-Up

Baseline blood pressure and heart rate should be measured and any preexisting hypertension or arrhythmia optimized before starting; an EKG is reasonable in patients with known cardiovascular disease or significant risk factors. Recheck blood pressure and heart rate within a few weeks of initiation and after each dose increase, then at routine follow-ups. Renal function should be checked at baseline and periodically because dose limits depend on eGFR; the comprehensive metabolic panel provides this information. Symptom tracking with the Epworth Sleepiness Scale or maintenance-of-wakefulness measures helps quantify response objectively, since subjective improvement can be hard to assess in patients who have lived with chronic sleepiness for years. For patients with sleep apnea, periodic confirmation of CPAP adherence (downloads from the device, typically reviewed by the sleep clinic) is essential, since residual sleepiness may otherwise reflect underused primary therapy rather than true treatment-resistant excessive daytime sleepiness.

Special Populations

Dose limits in renal impairment are: maximum 75 mg daily for eGFR 30-59 mL/min, maximum 37.5 mg daily for eGFR 15-29 mL/min, and avoidance for eGFR below 15 mL/min or end-stage renal disease. Hepatic impairment does not require adjustment because hepatic metabolism is minimal. Solriamfetol has not been studied in pediatric patients and is not recommended in this group. Limited human pregnancy data exist; a pregnancy registry is available, and women of reproductive potential should discuss risks and benefits before conception. Excretion into breast milk is unknown but expected based on lipophilicity. Older adults can use the medication, but renal function declines with age, so dose tailoring is often required and starting at the lower end is sensible. Patients with a history of substance use disorder should be assessed carefully because of Schedule IV status and abuse potential, although the lack of euphoric effect at therapeutic doses suggests low risk in most patients. Concomitant CNS stimulants should generally be avoided.

Lifestyle Foundations and Combination Strategies

Wake-promoting medications work best when paired with consistent attention to sleep hygiene, sleep schedule regularity, and treatment of underlying disorders. For patients with narcolepsy, scheduled brief naps (15-20 minutes once or twice daily) can supplement medication-based wakefulness and reduce the dose required for adequate function. Caffeine should be timed thoughtfully and limited late in the day to avoid additive insomnia with solriamfetol. For OSA patients, CPAP adherence often determines residual sleepiness more than medication choice; a structured CPAP coaching program, mask refitting, or alternative therapies such as oral appliances may rescue patients who appear to need wake-promoting agents. Bariatric weight loss, when appropriate, can substantially reduce OSA severity and sometimes eliminate the need for adjunctive sleepiness therapy. Driving safety is a critical conversation: untreated or undertreated excessive daytime sleepiness substantially raises motor vehicle accident risk, and many states have reporting requirements for diagnosed conditions. Patients should be advised about commercial driving restrictions and occupational safety implications. Combining solriamfetol with caffeine or other stimulating agents amplifies blood pressure and heart rate effects, so cumulative cardiovascular load should be weighed in patients with hypertension or coronary disease. Switching between wake-promoting agents (for example, from modafinil to solriamfetol) does not require a washout in most cases but should be coordinated with a sleep specialist or primary care physician. Patients with comorbid depression should be assessed for whether sleepiness reflects mood disorder rather than primary sleep disorder; antidepressant adjustment may be more appropriate than wake-promoting therapy. Our circadian rhythm sleep guide covers practical strategies for optimizing sleep-wake patterns. For patients with shift-work sleep disorder, a separate diagnosis with overlapping treatment options, modafinil and armodafinil are FDA-approved while solriamfetol is not, although off-label use occurs.

When to Contact Your Doctor

Seek prompt evaluation for chest pain, palpitations, marked elevation in blood pressure (systolic over 180 or diastolic over 110), severe headache, new agitation or panic, or signs of mania including racing thoughts, decreased need for sleep, or pressured speech. Persistent insomnia despite morning dosing, significant anxiety, or worsening of any underlying psychiatric condition warrants reassessment and possibly dose reduction or discontinuation. Allergic reactions including hives or facial swelling should prompt immediate care. Patients combining solriamfetol with monoamine oxidase inhibitors (or within 14 days of stopping an MAOI) are at risk for hypertensive crisis and the combination is contraindicated. New shortness of breath on exertion, ankle swelling, or unexplained fatigue may suggest cardiovascular effects and warrant evaluation.

If daytime sleepiness is impairing your work, driving safety, or quality of life, contact us or schedule a visit to evaluate underlying causes and discuss whether solriamfetol fits your treatment plan.