title: A double-blind, placebo-controlled, crossover study of sildenafil in obstructive sleep apnea.
abstract: 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
  Thirteen [corrected] 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, 15.6% +/- 9.6% vs 7.9% +/- 3.3%, [corrected] P < .01), without a difference in the nadir of oxygen desaturation. The mean arterial oxygen saturation also decreased (92.1% +/- 1.9% vs 93.8% +/- 1.3%, P = .03), [corrected] and the desaturation index increased (30.3 +/- 14.5 [corrected] events per hour vs 18.5 +/- 9.1 [corrected] events per hour, P < .001). There was an increase in apnea-hypopnea index (48.1 +/- 20.8 [corrected] events per hour vs 32.3 +/- 11.3 [corrected] events per hour, P = .001), [corrected] involving mostly obstructive events.
  
  
  CONCLUSIONS
  In patients with severe obstructive sleep apnea, a single 50-mg dose of sildenafil at bedtime worsens respiratory and desaturation events.
authors.affiliation: Department of Psychobiology, Federal University of São Paulo, São Paulo, Brazil. suelyroi@psicobio.epm.br
authors.forename: Suely
authors.initials: S
authors.lastname: Roizenblatt
authors.forename: Christian
authors.initials: C
authors.lastname: Guilleminault
authors.forename: Dalva
authors.initials: D
authors.lastname: Poyares
authors.forename: Fátima
authors.initials: F
authors.lastname: Cintra
authors.forename: Adriana
authors.initials: A
authors.lastname: Kauati
authors.forename: Sergio
authors.initials: S
authors.lastname: Tufik
mesh_terms: D018592:Cross-Over Studies; D004311:Double-Blind Method; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010726:Phosphodiesterase Inhibitors / Q000008:administration & dosage / Q000009:adverse effects*; D010879:Piperazines / Q000008:administration & dosage / Q000009:adverse effects*; D017286:Polysomnography; D011687:Purines; D012720:Severity of Illness Index; D000068677:Sildenafil Citrate; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D012894:Sleep Stages / Q000187:drug effects / Q000502:physiology; D013450:Sulfones; D013997:Time Factors
chemical_list: D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068677:Sildenafil Citrate; D010100:Oxygen