A nasal spray with a potassium channel blocker relieved nocturnal apnea

A clinical trial by Australian scientists has shown that the selective potassium channel blocker TASK 1/3, which increases upper airway dilator muscle activity and reduces pharyngeal spasm, reduces the severity of obstructive sleep apnea. As reported in the American Journal of Physiology - Heart and Circulatory Physiology, participants received the drug as a nasal spray during the study.

Under obstructive sleep apnea, doctors understand the absence of breathing in sleep for more than 10 seconds. It is associated with a high risk of serious adverse complications, but recent research in upper airway physiology and neurobiology has shown potential therapeutic targets. For example, people with sleep apnea are found to have narrow or flattened upper airways, and 70 percent of patients have additional functional risk factors: low respiratory arousal threshold or ineffective response of the muscles that dilate the upper airway. Therefore, sleep apnea is thought to arise from a combination of disturbed pharyngeal anatomy and inadequate function of the expander muscles.

One novel therapeutic approach for sleep apnea is the sensitization of upper airway mechanoreceptors, which mediate pressure-sensitive reflex activation of airway dilator muscles. Recently, a group of scientists conducted preclinical and human physiology studies to examine the role of potassium channels TASK-1 and TASK-3 (TASK 1/3) and three specific potassium (K+) channel antagonists, and found that local blockade of these channels when administered through the nose resulted in sustained improvement in upper airway patency over several hours by increasing upper airway expander muscle tone.

Now the same group led by Amal M. Osman (Amal M. Osman) from Flinders University has tested the effectiveness of a nasal spray with an inhibitor of these channels on the symptoms and severity of sleep apnea. A total of ten participants took part in the study, with whom three overnight polysomnographic sleep studies were performed at one week intervals between visits. Immediately before bedtime, patients received either 160 micrograms of nasal spray medication, nasal spray with placebo (saline), or 160 micrograms of nasal spray medication along with a chin strap or mouth tape to provide nasal breathing only.

The study participants were mostly obese and had severe obstructive sleep apnea. Researchers found that morning systolic and diastolic blood pressure readings were lower with the medicated spray compared to placebo. No changes in sleep quality or functioning the next day were reported depending on the condition of the medication.

Seven of 10 study participants had a decrease in the apnea-hypopnea index, which reflects the frequency of episodes of sleep apnea and hypopnea, when using the medicated nasal spray. Similar results were obtained when similar indices were analyzed (p = 0.04). In addition, the researchers recorded that participants spent more time lying on their backs during the night after taking the medicated spray (p = 0.006). All other sleep parameters such as total sleep time, sleep onset latency, sleep efficiency, arousal index and sleep architecture did not differ between the groups. Also, patients who used the blocker spray had a significant 28 percent reduction in hypoxic load during sleep (p = 0.02).

This small clinical trial demonstrates the sufficient efficacy and safety of TASK 1/3 channel blockers for obstructive sleep apnea. Further studies should scale this result, and in addition, researchers hope that the spray may be useful for safer general anesthesia.

Apnea can lead to sleep disturbances. Physical activity may also help: Australian and British scientists have found that moderate to high levels of physical activity are associated with a reduced risk of death in people with sleep disorders.