title: An open-label, multicentre, randomized, crossover study comparing sildenafil citrate and tadalafil for treating erectile dysfunction in men naïve to phosphodiesterase 5 inhibitor therapy.
abstract: OBJECTIVE
  To compare treatment preference, efficacy, and tolerability of sildenafil citrate (sildenafil) and tadalafil for treating erectile dysfunction (ED) in men naïve to phosphodiesterase 5 (PDE5) inhibitor therapy.
  
  
  METHODS
  This was an open-label, crossover study of sildenafil and tadalafil (taken as needed). After a 4-week baseline assessment, 367 men with ED (mean age 54 years) were randomized to receive sildenafil for 12 weeks followed by tadalafil for 12 weeks or vice versa (8-week dose optimization and 4-week assessment phases). During dose optimization, patients started taking 25- or 50-mg sildenafil or 10-mg tadalafil and could titrate to find their optimum dose (25-, 50- or 100-mg sildenafil; 10- or 20-mg tadalafil). After completing both 12-week periods, patients chose which treatment to continue during an 8-week extension. Efficacy was measured with the International Index of Erectile Function (IIEF) and Sexual Encounter Profile (SEP) diary.
  
  
  RESULTS
  Of the 291 men who completed both treatments, 85 (29%) chose sildenafil and 206 (71%) chose tadalafil (P < 0.001) for the 8-week extension. The IIEF erectile function domain scores were 14.2 at baseline, 23.9 at endpoint on sildenafil, and 24.3 at endpoint on tadalafil (P = 0.08, sildenafil vs tadalafil). The mean per patient percentage success scores for SEP2 (penetration) were: baseline (46%), sildenafil (post-baseline 82%) and tadalafil (post-baseline 85%; P = 0.06, sildenafil vs tadalafil), and for SEP3 (successful intercourse) were: baseline (19%), sildenafil (post-baseline 72%), and tadalafil (post-baseline 77%; P = 0.003, sildenafil vs tadalafil). The only treatment-emergent adverse events that were reported by >5% of men were headache and flushing.
  
  
  CONCLUSIONS
  In men with ED who were naïve to PDE5 inhibitor therapy, sildenafil and tadalafil were both effective and well tolerated. After treatment with sildenafil and tadalafil, 29% of men chose sildenafil and 71% chose tadalafil for ED therapy during an 8-week extension.
authors.affiliation: St. James University Hospital, Pyrah Department of Urology, Leeds, UK. ian.eardley@btinternet.com
authors.forename: Ian
authors.initials: I
authors.lastname: Eardley
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Mirone
authors.forename: Francesco
authors.initials: F
authors.lastname: Montorsi
authors.forename: David
authors.initials: D
authors.lastname: Ralph
authors.forename: Philip
authors.initials: P
authors.lastname: Kell
authors.forename: Margaret R
authors.initials: MR
authors.lastname: Warner
authors.forename: Yanli
authors.initials: Y
authors.lastname: Zhao
authors.forename: Anthony
authors.initials: A
authors.lastname: Beardsworth
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002243:Carbolines / Q000009:adverse effects / Q000627:therapeutic use*; D018592:Cross-Over Studies; D007172:Erectile Dysfunction / Q000188:drug therapy*; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D017060:Patient Satisfaction; D010726:Phosphodiesterase Inhibitors / Q000009:adverse effects / Q000627:therapeutic use*; D010879:Piperazines / Q000009:adverse effects / Q000627:therapeutic use*; D011687:Purines; D000068677:Sildenafil Citrate; D013450:Sulfones; D000068581:Tadalafil; D016896:Treatment Outcome; D006113:United Kingdom
chemical_list: D002243:Carbolines; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068581:Tadalafil; D000068677:Sildenafil Citrate