A double-blind, placebo-controlled, crossover study of sildenafil in obstructive sleep apnea

Background: Sildenafil prolongs the action of cyclic guanosine monophosphate and nitric oxide by inhibiting cyclic guanosine monophosphate - specific phosphodiesterase 5. It is largely used for erectile dysfunction, a highly prevalent condition in obstructive sleep apnea. Because nitric oxide promotes upper airway congestion, muscle relaxation, and pulmonary vasodilation, the aim of this study was to establish the impact of a single 50-mg dose of sildenafil on the sleep of patients with severe obstructive sleep apnea. Methods: Fourteen middle-aged men with severe obstructive sleep apnea were consecutively selected for this double-blind, placebo-controlled, crossover study. Exclusion criteria were obesity, cardiovascular and/ or respiratory disease, and conditions that interfere with sleep. All-night polysomnography was preceded by a single 50-mg dose of sildenafil or matching placebo randomly administered at bedtime, after a washout period of 1 week. Results: In comparison to placebo, a single 50-mg dose of sildenafil significantly increased the percentage of total sleep time with an arterial oxygen saturation of less than 90% (mean +/- SD, 14.2% +/- 9.1% vs 8.5% +/- 3.2%, P < .01), without a difference in the nadir of oxygen desaturation. The mean arterial oxygen saturation also decreased (92.1% +/- 1.91% vs 93.8% +/- 1.3%, P =. 02), and the desaturation index increased (30.3 +/- 18.1 events per hour vs 18.5 +/- 14.6 events per hour, P < . 001). There was an increase in apnea-hypopnea index (42.4 +/- 25.5 events per hour vs 34.6 +/- 24.1 events per hour, P =. 01), involving mostly obstructive events. Conclusion: In patients with severe obstructive sleep apnea, a single 50-mg dose of sildenafil at bedtime worsens respiratory and desaturation events.