“How does a pill affect only the muscle tone of the ‘upper airways’?”
From the underlying study:
AD109 increases upper airway muscular tone primarily through the action of atomoxetine.
Atomoxetine increases norepinephrine levels in the brain by inhibiting its reuptake.
Norepinephrine is a neurotransmitter that enhances the activity of motor neurons controlling upper airway muscles, particularly the genioglossus muscle in the tongue. This muscle is critical for maintaining airway patency during sleep. By boosting norepinephrine, atomoxetine stimulates these motor neurons, leading to increased muscle tone and reduced airway collapsibility, which is beneficial for conditions like obstructive sleep apnea (OSA).
Interesting that the study characterizes Norepinephrine only in terms of the airways in the excerpt you posted. The first paragraph under Norphinephrine in wikipedia talks about it being a alertness and fight-or-flight neurotransmitter also increases heart rate and blood pressure. This seems like a terrible idea for sleep!
Per wiki:
“The general function of norepinephrine is to mobilize the brain and body for action. Norepinephrine release is lowest during sleep, rises during wakefulness, and reaches much higher levels during situations of stress or danger, in the so-called fight-or-flight response. In the brain, norepinephrine increases arousal and alertness, promotes vigilance, enhances formation and retrieval of memory, and focuses attention; it also increases restlessness and anxiety. In the rest of the body, norepinephrine increases heart rate and blood pressure, triggers the release of glucose from energy stores, increases blood flow to skeletal muscle, reduces blood flow to the gastrointestinal system, and inhibits voiding of the bladder and gastrointestinal motility.”