Sleep apnea is estimated to affect 1 in 5 American adults, and there are currently no drugs available to treat it. But a large-scale clinical trial now offers hope, proving that a drug that uses a synthetic version of the main psychoactive substance in cannabis is effective for treating the disorder.
The drug is called dronabinol, and it is based on a synthetic version of Delta-9 tetrahydrocannabinol (THC) — the main psychoactive compound responsible for the "high" in cannabis use.
The randomized clinical trial is the longest and largest of its kind, and the results are from its second phase. Dronabinol is already in use for the treatment of nausea and vomiting in patients undergoing chemotherapy.
David W. Carley, a professor of biobehavioral health sciences at the University of Illinois at Chicago (UIC), jointly led the study with Dr. Phyllis Zee, professor of neurology at Northwestern University Feinberg School of Medicine and director of the Northwestern Medicine Sleep Disorders Center, both in Chicago, IL.
At least a mild form of sleep apnea is thought to affect 1 in 5 Americans, and treatment options are limited. Obstructive sleep apnea — the most prevalent form of the condition — is usually treated mechanically with a continuous positive airway pressure (CPAP) device. However, treatment adherence to this mechanical option is very poor.
Recurrent, untreated sleep apnea may lead to cardiovascular problems, such as heart disease and stroke. "There is a tremendous need for effective, new treatments [for] obstructive sleep apnea," says Prof. Carley, who is also the first author of the paper.
The drug tested in this trial — results of which are published in journal Sleep — works by targeting the brain. Dr. Zee explains, "The CPAP device targets the physical problem but not the cause."
"The drug targets the brain and nerves that regulate the upper airway muscles. It alters the neurotransmitters from the brain that communicate with the muscles."
"When people take a pill to treat apnea, they are treated for the entire night," adds Prof. Carley.
Testing dronabinol in sleep apnea patients
Prof. Carley and colleagues recruited 73 adult participants who had moderate or severe sleep apnea.
Participants were divided into three groups: one group received a low dose of dronabinol, a second group received a high dose, and a third, control group received placebo.
The groups took the treatment or placebo every day, 1 hour before bedtime, for a period of 6 weeks.
Their sleepiness and wakefulness were assessed using standard tests, and an overall apnea/hypopnea index was determined for each participant. Hypopnea refers to excessively shallow breathing.
Those who took the highest dose, i.e., 10 milligrams of dronabinol, reported the highest satisfaction with the treatment. They showed decreased signs of subjective sleepiness and a lower incidence of apnea and hypopnea episodes.
Compared with full adherence to the mechanical CPAP device — which is rare — the new drug reduced apnea symptoms by 33 percent.
The first viable sleep apnea drug?
The authors concede that even larger clinical trials are needed to figure out the best way to use cannabinoids for the treatment of sleep apnea.
Until then, the authors caution against smoking or inhaling cannabis, as it will not provide the same benefits for sleep apnea. "Different types of cannabis have different ingredients," Dr. Zee says. "The active ingredient may not be exactly the same as what's indicated for sleep apnea."
Prof. Carley also weighs in, saying, "Cannabis contains dozens of active ingredients, but we tested just purified delta-9 THC."
"Better understanding of this [drug] will help us develop more effective and personalized treatments for sleep apnea," Dr. Zee adds.
Overall, however, the findings are encouraging. The authors conclude:
"These findings support the therapeutic potential of cannabinoids in patients with [obstructive sleep apnea]. In comparison to placebo, dronabinol was associated with lower [apnea/hypopnea index ], improved subjective sleepiness, and greater overall treatment satisfaction."
"By providing a path toward the first viable obstructive sleep apnea drug, our studies could have a major impact on clinical practice," says Prof. Carley.