Tiagabine to Enhance Slow Wave Sleep in Patients With Sleep Apnea

Phase 2

Completed

Brief Summary: Obstructive sleep apnea (OSA) is common and has major health implications but treatment options are limited. Interestingly, the severity of OSA is profoundly reduced in deep sleep (called "slow wave sleep"), potentially via an increase in the stimulus required to arouse from sleep. Here the investigators test the idea that the medication called "tiagabine" improves slow wave sleep and reduces OSA severity. The investigators will also test whether tiagabine raises the arousal threshold (more negative esophageal pressure), and whether detailed OSA "phenotyping" characteristics can predict the improvement in OSA severity with this intervention.

Detailed Description: The current study tests the primary hypothesis that tiagabine improves sleep apnea severity in patients with moderate-to-severe sleep apnea (apnea hypopnea index measured in supine non-REM sleep; hypopneas defined by 3% desaturation or arousal). The investigators test three secondary hypotheses that tiagabine:

1. increases the proportion of total sleep time in slow wave sleep

2. raises the non-REM arousal threshold (more negative esophageal pressure) via (1).

3. is preferentially effective in patients whose OSA phenotype predicts that an increase in the arousal threshold is sufficient to resolve OSA versus those without such favorable physiology. Favorable physiology is defined here as having a low ventilatory drive at which stable breathing is theoretically feasible ("stable Vdrive" is \<100% above eupneic ventilatory drive) due to any combination of a "high" upper airway muscle response, "good" passive anatomy (high Vpassive), and "low" steady-state loop gain (see Owens RL et al SLEEP 2014; Wellman A et al J Appl Physiol 2011, 2013; Eckert DJ et al 2013 AJRCCM).

Recruitment & Eligibility

Inclusion Criteria

Exclusion Criteria

Arm && Interventions

Group	Intervention	Description
Placebo	Placebo	Placebo PO before sleep
Tiagabine	Tiagabine	Tiagabine PO 12 mg before sleep

Primary Outcome Measures

Name	Time	Method
Apnea Hypopnea Index (AHI)	1 night	Number of apneas + hypopneas per hour of sleep. Hypopnea criteria: reduction in 30% of baseline flow plus 3% desaturation or arousal.

Secondary Outcome Measures

Name	Time	Method
Slow Wave Sleep (% Total Sleep Time)	1 night	Fraction of sleep spent in stage N3
Arousal Threshold (Esophageal Pressure Swing)	1 night	The arousal threshold was quantified as the mean of all the nadir negative esophageal pressure swings immediately preceding an arousal at the end of an obstructive apnea or hypopnea during both placebo and tiagabine nights.