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Effect of Venlafaxine on Apnea-Hypopnea Index in Patients With Sleep Apnea: A Randomized, Double-Blind Crossover Study.

  • Author(s): Schmickl, Christopher N
  • Li, Yanru
  • Orr, Jeremy E
  • Jen, Rachel
  • Sands, Scott A
  • Edwards, Bradley A
  • DeYoung, Pamela
  • Owens, Robert L
  • Malhotra, Atul
  • et al.


One of the key mechanisms underlying OSA is reduced pharyngeal muscle tone during sleep. Data suggest that pharmacologic augmentation of central serotonergic/adrenergic tone increases pharyngeal muscle tone.

Research question

We hypothesized that venlafaxine, a serotonin-norepinephrine reuptake inhibitor, would improve OSA severity.

Study design and methods

In this mechanistic, randomized, double-blind, placebo-controlled crossover trial, 20 patients with OSA underwent two overnight polysomnograms ≥ 4 days apart, receiving either 50 mg of immediate-release venlafaxine or placebo before bedtime. Primary outcomes were the apnea-hypopnea index (AHI) and peripheral oxygen saturation (Spo2) nadir, and secondary outcomes included sleep parameters and pathophysiologic traits with a view toward understanding the impact of venlafaxine on mechanisms underlying OSA.


Overall, there was no significant difference between venlafaxine and placebo regarding AHI (mean reduction, -5.6 events/h [95% CI, -12.0 to 0.9]; P = .09) or Spo2 nadir (median increase, +1.0% [-0.5 to 5]; P = .11). Venlafaxine reduced total sleep time, sleep efficiency, and rapid eye movement (REM) sleep, while increasing non-REM stage 1 sleep (Pall < .05). On the basis of exploratory post hoc analyses venlafaxine decreased ("improved") the ventilatory response to arousal (-30%; P = .049) and lowered ("worsened") the predicted arousal threshold (-13%; [P = .02]; ie, more arousable), with no effects on other pathophysiologic traits (Pall ≥ .3). Post hoc analyses further suggested effect modification by arousal threshold (P = .002): AHI improved by 19% in patients with a high arousal threshold (-10.9 events/h [-3.9 to -17.9]) but tended to increase in patients with a low arousal threshold (+7 events/h [-2.0 to 16]). Other predictors of response were elevated AHI and less collapsible upper airway anatomy at baseline (|r| > 0.5, P ≤ .02).


In unselected patients, venlafaxine simultaneously worsened and improved various pathophysiologic traits, resulting in a zero net effect. Careful patient selection based on pathophysiologic traits, or combination therapy with drugs countering its alerting effects, may produce a more robust response.

Trial registry; No.: NCT02714400; URL:

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