title: Effectiveness of oral L-arginine in first-line treatment of erectile dysfunction in a controlled crossover study.
abstract: OBJECTIVE
  Relaxation of cavernous smooth muscle is a parasympathetic and non-adrenergic, non-cholinergic mediated process which requires nitric oxide (NO). NO is synthesized from L-arginine by NO synthase (NOS). Some studies report good clinical results under oral L-arginine medication in the treatment of erectile dysfunction. We examined the effectiveness and safety of L-arginine in the treatment of mixed-type impotence.
  
  
  METHODS
  32 patients (mean age 51.6 years) with mixed-type impotence diagnosed according to the results of sexual history and urological examination were enrolled in a randomized, placebo-controlled, crossover comparison of an oral placebo with 3 x 500 mg L-arginine/day. A validated questionnaire (KEED) was used to define the grade of impotence with a score. The treatment consisted of two 17-day courses (50 tablets). After a 7-day washout period the patients who initially received the placebo for 17 days were switched to L-arginine and vice versa. We assessed the efficacy with the validated questionnaire at the end of each drug period.
  
  
  RESULTS
  30 patients (94%) completed the whole treatment schedule. Five (17%) patients reported a significant improvement in erectile function at the end of the L-arginine phase and 6 (20%) patients after the placebo period. 17 (56%) patients showed little improvement with L-arginine and 13 (43%) with placebo. In 8 patients (27%) of the verum group there was either no change in the ED score or even a slight worsening. No statistical difference in the impotence scores were found. No drug-related adverse effects occurred with L-arginine treatment.
  
  
  CONCLUSIONS
  Oral L-arginine 3 x 500 mg/day is not better than placebo as a first-line treatment for mixed-type impotence.
authors.affiliation: Department of Urology, University of Cologne, Germany. tklotz@t-online.de
authors.forename: T
authors.initials: T
authors.lastname: Klotz
authors.forename: M J
authors.initials: MJ
authors.lastname: Mathers
authors.forename: M
authors.initials: M
authors.lastname: Braun
authors.forename: W
authors.initials: W
authors.lastname: Bloch
authors.forename: U
authors.initials: U
authors.lastname: Engelmann
mesh_terms: D000284:Administration, Oral; D001120:Arginine / Q000008:administration & dosage / Q000627:therapeutic use*; D018592:Cross-Over Studies; D007172:Erectile Dysfunction / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000502:physiology; D010410:Penile Erection / Q000502:physiology
chemical_list: D009569:Nitric Oxide; D001120:Arginine; D019001:Nitric Oxide Synthase