title: A multicenter, randomized, double-blind, crossover study to evaluate patient preference between tadalafil and sildenafil.
abstract: OBJECTIVE
  To assess patient preference for erectile dysfunction treatment between either sildenafil or tadalafil, each administered with their respective dosing instructions, and to evaluate preference for either sildenafil or tadalafil dosing instructions during tadalafil therapy.
  
  
  METHODS
  We conducted a randomized, double-blind, crossover study consisting of four treatment arms. Because the dosing instructions for sildenafil and tadalafil are different, a unique methodology using sham placebo arms was employed to maintain the blind. To assess drug preference, 219 patients were randomized to either sildenafil 50 mg or tadalafil 20 mg, with dosing instructions reflecting their respective product profiles. To assess dosing instruction preference during tadalafil therapy, 46 patients were randomized to tadalafil 20 mg with either tadalafil or sildenafil dosing instructions. After 12 weeks, patients were crossed-over. After 4 weeks of each treatment, all patients following sildenafil dosing instructions were offered the opportunity for an upward dose titration. In a double-blind fashion, all patients who requested an upward titration received additional capsules. To mimic the pattern of dose usage observed in clinical practice, the number of patients who received additional double-blind active medication was limited to 35% of patients taking sildenafil in each treatment period in each country. Following the crossover treatment period, patients chose their preferred double-blind treatment with dosing instructions to receive in the 12-week extension period.
  
  
  RESULTS
  In the drug preference assessment, 132 of 181 (73%) evaluable patients chose to receive tadalafil (p < 0.001) during the extension period. In the dosing instruction preference assessment, 24 of 36 (67%) evaluable patients preferred tadalafil with tadalafil dosing instructions (p = 0.046). Sildenafil and tadalafil were well tolerated.
  
  
  CONCLUSIONS
  In the doses utilized in this study, 73% of patients preferred tadalafil with tadalafil dosing instructions for the treatment of their erectile dysfunction over sildenafil with sildenafil dosing instructions. During tadalafil therapy, 67% of patients preferred tadalafil dosing instructions over sildenafil dosing instructions.
authors.affiliation: Urology Practice, AM Krummbogen 15, 35039 Marburg, Germany. avkeitz@aol.com
authors.forename: Alexander
authors.initials: A
authors.lastname: von Keitz
authors.forename: Jacob
authors.initials: J
authors.lastname: Rajfer
authors.forename: Scott
authors.initials: S
authors.lastname: Segal
authors.forename: Aileen
authors.initials: A
authors.lastname: Murphy
authors.forename: Jonathan
authors.initials: J
authors.lastname: Denne
authors.forename: Timothy
authors.initials: T
authors.lastname: Costigan
authors.forename: Daniel
authors.initials: D
authors.lastname: Lockhart
authors.forename: Charles M
authors.initials: CM
authors.lastname: Beasley
authors.forename: Jeffrey T
authors.initials: JT
authors.lastname: Emmick
mesh_terms: D000328:Adult; D000368:Aged; D002243:Carbolines / Q000008:administration & dosage*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D007172:Erectile Dysfunction / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017060:Patient Satisfaction; D010726:Phosphodiesterase Inhibitors / Q000008:administration & dosage*; D010879:Piperazines / Q000008:administration & dosage*; D011687:Purines; D000068677:Sildenafil Citrate; D013450:Sulfones; D000068581:Tadalafil
chemical_list: D002243:Carbolines; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068581:Tadalafil; D000068677:Sildenafil Citrate