Solriamfetol
Solriamfetol (Sunosi) is a Schedule IV FDA-approved medication indicated for treatment of EDS in adults with narcolepsy or obstructive sleep apnea. The precise mechanism of action is unknown, but this medication is believed to inhibit both dopamine and norepinerphrine reuptake in the brain, similar to the widely-prescribed NDRI buproprion. In a 12-week RCT study on its effects on narcolepsy in adults, solriamfetol improved important measures of wakefulness and sleepiness, without associated polysomnographic evidence of significant sleep disruption.4 In another 12-week RCT study of solriamfetol in adult patients with EDS related to OSA, there was a dose-dependent improvement in measures of wakefulness.5 Some notable side-effects seen with this medication include anxiety and elevated mood, as well as increases in blood pressure. A subsequent study of this medication found that it was efficacious at maintenance of improvements at 6 months.6 Given the theorized mechanism of action as an NDRI, future observation and studies could provide insights on its effect on depression, as well.
Pitolisant
Histaminergic neurons within the CNS play an important role in the promotion of wakefulness. Pitolisant (Wakix) is an interesting wakefulness-promoting agent for adult patients with narcolepsy. It acts as an inverse agonist and antagonist of histamine H3 receptors, resulting in a reduction of the usual feedback inhibition effected through the H3 receptor, thereby enhancing CNS release of histamine and other neurotransmitters. This medication was approved by the FDA in August 2019 and is currently indicated for adult patients with narcolepsy. The HARMONY I trial comparing pitolisant with both placebo and modafinil in adults with narcolepsy and EDS demonstrated improvement in measures of sleepiness and maintenance of wakefulness over placebo, and noninferiority to modafinil.7 In addition, pitolisant had a favorable side-effect profile compared with modafinil. Subsequent studies have reaffirmed the safety profile of pitolisant, including its minimal abuse potential. In one recent placebo-controlled trial of the use of pitolisant in a population of 268 adults with positive airway pressure (PAP) non-adherence, pitolisant was found to improve measures of EDS and related patient-reported measurements in patients with OSA who were CPAP nonadherent.8 Though generally well-tolerated by patients, in initial clinical trials pitolisant was associated with increased headache, insomnia, and nausea relative to placebo, among other less commonly reported adverse effects. Pitolisant is QT interval-prolonging, so caution must be taken when using this medication in combination other medications which may induce QT interval prolongation, including SSRIs.
Future directions
Greater awareness of the hypersomnias and their management has led to improved outcomes and access to care for these patients, yet these disorders remain burdensome and the treatments imperfect. Looking forward, novel pharmacotherapies that target underlying mechanisms rather than symptom palliation will allow for more precise treatments. Ongoing investigations of hypocretin receptor agonists seek to target one critical central mediator of wakefulness. Recent studies have highlighted the association of dysautonomia with hypersomnia, offering interesting insight into possible future targets to improve the function and quality of life of these patients.9 Similarly, understanding of the interplay between psychiatric disorders and primary and secondary hypersomnias may offer new therapeutic pathways.
As treatment plans targeting hypersomnia become more comprehensive and holistic, with an increased emphasis on self-care, sleep hygiene, and mental health awareness, in addition to mechanism-specific treatments, we hope they will ultimately provide improved symptom and burden relief for our patients.
Dr. Shih Yee-Marie Tan Gipson is a psychiatrist and Dr. Kevin Gipson is a sleep medicine specialist, both with Massachusetts General Hospital, Boston.
References
1 Dauvilliers, et al. Hypersomnia. Dialogues Clin Neurosci. 2005;7(4):347-356.
2 Trotti, et al. Clarithromycin in gamma-aminobutyric acid-related hypersomnolence: A randomized, crossover trial. Ann Neurol. 2015;78(3):454-465. doi: 10.1002/ana.24459.
3 Trotti, et al. Flumazenil for the treatment of refractory hypersomnolence: Clinical experience with 153 patients. J Clin Sleep Med. 2016;12(10):1389-1394. doi: 10.5664/jcsm.6196.
4 Thorpy, et al. A randomized study of solriamfetol for excessive sleepiness in narcolepsy. Ann Neurol. 2019; 85(3):359-370. doi: 10.1002/ana.25423.
5 Schweitzer, et al. Solriamfetol for excessive sleepiness in obstructive sleep apnea (TONES 3): A randomized controlled trial. Am J Respir Crit Care Med. 2019;199(11):1421-1431. doi: 10.1164/rccm.201806-1100OC.
6 Malhotra, et al. Long-term study of the safety and maintenance of efficacy of solriamfetol (JZP-110) in the treatment of excessive sleepiness in participants with narcolepsy or obstructive sleep apnea. Sleep. 2020; 43(2): doi: 10.1093/sleep/zsz220.
7 Dauvilliers, et al. Pitolisant versus placebo or modafinil in patients with narcolepsy: a double-blind, randomised trial. Lancet Neurol. 2013;12(11):1068-1075. doi: 10.1016/S1474-4422(13)70225-4.
8 Dauvilliers, et al. Pitolisant for daytime sleepiness in obstructive sleep apnea patients refusing CPAP: A randomized trial. Am J Respir Crit Care Med. 2020. doi: 10.1164/rccm.201907-1284OC.
9 Miglis, et al. Frequency and severity of autonomic symptoms in idiopathic hypersomnia. J Clin Sleep Med. 2020; 16(5):749-756. doi: 10.5664/jcsm.8344.