title: Impact of low testosterone on response to treatment with tadalafil 5 mg once daily for erectile dysfunction.
abstract: OBJECTIVE
  To evaluate, posthoc, the relationship between serum total testosterone and response to therapy in a study of tadalafil once daily for erectile dysfunction (ED).
  
  
  METHODS
  Men were aged ≥18 years, with ≥3-month history of ED and partial prior response to on-demand (PRN) phosphodiesterase type 5 inhibitor (PDE5I) therapy. A 4-week maximum-dose PRN PDE5I run-in was followed by a 4-week nondrug washout period, then randomization to tadalafil 2.5 mg titrated to 5 mg or tadalafil 5 mg (pooled for analyses) or placebo once daily for 12 weeks. Analyses compared endpoint efficacy results between low- (<300 ng/dL) vs normal-testosterone (≥300 ng/dL) level subgroups.
  
  
  RESULTS
  Improvements for tadalafil vs placebo were significant for the International Index of Erectile Function (IIEF) Erectile Function domain, Intercourse Satisfaction domain, Overall Satisfaction domain, and Question 15 (confidence in the ability to get and keep an erection; all P<.001), and for the Sexual Encounter Profile Questions 1-5 (all P≤.011). Analysis of covariance modeling identified significant treatment-by-subgroup interactions for the IIEF-Overall Satisfaction domain and erection confidence question and Sexual Encounter Profile Question 3. Comparing between tadalafil-treated testosterone subgroups, the IIEF-Erectile Function domain scores improved significantly more in men with normal vs low testosterone (P=.022); no other significant differences were identified for either placebo or tadalafil. No significant differences in pre-existing conditions were observed between tadalafil and placebo within the normal- and low-testosterone subgroups.
  
  
  CONCLUSIONS
  In men with partial response to a PRN PDE5I, tadalafil 5 mg once daily significantly improved ED and sexual function vs placebo irrespective of testosterone levels.
authors.affiliation: Premier Medical Group of the Hudson Valley, Poughkeepsie, NY. Electronic address: evanrgold@gmail.com.
authors.forename: Evan R
authors.initials: ER
authors.lastname: Goldfischer
authors.affiliation: Division of Urology, Department of Surgery, University of Tennessee Graduate School of Medicine, Knoxville, TN.
authors.forename: Edward D
authors.initials: ED
authors.lastname: Kim
authors.affiliation: Division of Urology, Urology Residency Training Program, Cooper Medical School of Rowan University, Camden, NJ.
authors.forename: Allen D
authors.initials: AD
authors.lastname: Seftel
authors.affiliation: Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN.
authors.forename: Simin K
authors.initials: SK
authors.lastname: Baygani
authors.affiliation: Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN.
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Burns
mesh_terms: D000284:Administration, Oral; D000328:Adult; D002243:Carbolines / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D007172:Erectile Dysfunction / Q000097:blood / Q000188:drug therapy*; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010410:Penile Erection / Q000187:drug effects; D058986:Phosphodiesterase 5 Inhibitors / Q000008:administration & dosage*; D011446:Prospective Studies; D012016:Reference Values; D018570:Risk Assessment; D000068581:Tadalafil; D013739:Testosterone / Q000097:blood / Q000172:deficiency*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D002243:Carbolines; D058986:Phosphodiesterase 5 Inhibitors; D013739:Testosterone; D000068581:Tadalafil