0557 THE ROLE OF NIGHTLY ZOPICLONE ON OBSTRUCTIVE SLEEP APNEA SEVERITY AND SYMPTOMS IN PEOPLE WITH LOW TO MODERATE RESPIRATORY AROUSAL THRESHOLDS: A RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED TRIAL

Single-night studies indicate that hypnotics can worsen obstructive sleep apnea (OSA) in some people and reduce OSA severity in others. However, clinical trial data beyond night 1 is lacking. Accordingly, this study aimed to determine the effects of 1 month of nightly zopiclone on OSA severity and next day sleepiness and alertness in people predicted to yield a reduction in OSA severity with zopiclone (ACTRN12613001106729). Screening polysomnography (PSG) quantified the respiratory arousal threshold (nadir epiglottic pressure prior to arousal) and nadir SaO2 in 69 individuals. 30 eligible OSA patients (AHI =22.4 ± 11.3 events/h sleep) with a low to moderate respiratory arousal threshold (0 to -25cmH2O) and nadir SaO2≥75% then underwent PSG on three occasions at baseline, night 1 and night 30. Participants received either nightly zopiclone (7.5 mg) or placebo during the 30 day trial according to a double-blind, randomized, parallel design. Subjective sleepiness (ESS and KSS) and next day alertness during a 30 minute driving simulator task (AusEd) were performed at each visit. The mean reduction in AHI from baseline on night 30 was 5.9 ± 10.2 during zopiclone vs. 2.4 ± 5.5 events/h sleep during placebo (p=0.2). The change in nadir SaO2 was also not different between zopiclone and placebo (-0.9 ± 3.2 vs. -0.1 ± 5.6 %, p=0.6). Similarly, neither the change in ESS (-1.3 ± 2.7 vs. -0.2 ± 2.4), KSS (0 ± 1.8 vs. 0 ± 1.7) or steering deviation (0.3 ± 4.4 vs. 3.9 ± 10.3 cm) during the AusEd driving task from baseline to night 30 significantly differed between zopiclone vs. placebo (p>0.05). One month of nightly zopiclone does not worsen OSA severity, daytime sleepiness or simulated driving performance in OSA patients with low to moderate respiratory arousal thresholds who do not have major hypoxemia at baseline. These findings challenge previous assumptions about the role of hypnotics in these patients. National Health and Medical Research Council of Australia (1042493).