title: Sildenafil induces retinal vasodilatation in healthy subjects.
abstract: BACKGROUND
  The cardiovascular effects of sildenafil (Viagra), a selective inhibitor of phosphodiesterase type 5 (PDE5), have been extensively studied. However, its effect on human retinal arteries and veins has not yet been investigated. The effect of a single dose administration of sildenafil on the retinal vessel diameters of healthy subjects was evaluated.
  
  
  METHODS
  Sildenafil 50 mg was administered to 10 healthy subjects (male:female = 4:6; mean age 31 (SD 6) years). The diameters of retinal arteries and veins were measured by means of a retinal vessel analyser (RVA) immediately before and at 30, 60, 90, and 120 minutes after sildenafil uptake. Blood pressure, heart rate, and intraocular pressure were monitored in parallel.
  
  
  RESULTS
  A significant increase of 5.8% (p<0.001) in both retinal arterial and venous diameters was found 30 minutes after sildenafil uptake. The diameters returned to baseline after 120 minutes. A mild systemic hypotensive response was seen. Changes in heart rate and intraocular pressure were not observed.
  
  
  CONCLUSIONS
  Sildenafil causes a significant dilatation of retinal arteries and veins in healthy subjects. A possible role for PDE5 in the regulation of retinal blood flow is implicated.
authors.affiliation: University Eye Clinic Basel, Switzerland.
authors.forename: Mona
authors.initials: M
authors.lastname: Pache
authors.forename: Peter
authors.initials: P
authors.lastname: Meyer
authors.forename: Christian
authors.initials: C
authors.lastname: Prünte
authors.forename: Selim
authors.initials: S
authors.lastname: Orgül
authors.forename: Ines
authors.initials: I
authors.lastname: Nuttli
authors.forename: Josef
authors.initials: J
authors.lastname: Flammer
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000502:physiology; D010726:Phosphodiesterase Inhibitors / Q000009:adverse effects / Q000494:pharmacology*; D010879:Piperazines / Q000009:adverse effects / Q000494:pharmacology*; D011687:Purines; D012161:Retinal Artery / Q000187:drug effects / Q000502:physiology; D012169:Retinal Vein / Q000187:drug effects / Q000502:physiology; D012171:Retinal Vessels / Q000187:drug effects*; D000068677:Sildenafil Citrate; D013450:Sulfones; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D009569:Nitric Oxide; D000068677:Sildenafil Citrate