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

Abstract

Background: 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.

Results: 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).

Interpretation: 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: ClinicalTrials.gov; No.: NCT02714400; URL: www.clinicaltrials.gov.

Keywords: OSA; lung; pharmacotherapy; pharyngeal muscle tone; venlafaxine.

Copyright © 2020 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1

CONSORT flow diagram (for crossover trials). CONSORT = Consolidating Standards of Reporting Trials.

Figure 2

Changes in apnea-hypopnea index (AHI, events/h) with venlafaxine vs placebo. Diamonds and bars show mean and SD for each condition (red, placebo; blue, venlafaxine). Circles denote individuals’ AHI.

Figure 3

Change in AHI with venlafaxine vs placebo stratified by OSA severity and the predicted arousal threshold, using standard cutoffs. Diamonds and bars show mean and 95% CI for each group; red circles denote individuals’ change in AHI. See Figure 2 legend for expansion of abbreviation.