Effectiveness of oral L-arginine in first-line treatment of erectile dysfunction in a controlled crossover study

Urol Int. 1999;63(4):220-3. doi: 10.1159/000030454.

Abstract

Background and aims: 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.

Conclusion: Oral L-arginine 3 x 500 mg/day is not better than placebo as a first-line treatment for mixed-type impotence.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Administration, Oral
  • Arginine / administration & dosage
  • Arginine / therapeutic use*
  • Cross-Over Studies
  • Erectile Dysfunction / drug therapy*
  • Humans
  • Male
  • Middle Aged
  • Nitric Oxide / metabolism
  • Nitric Oxide Synthase / physiology
  • Penile Erection / physiology

Substances

  • Nitric Oxide
  • Arginine
  • Nitric Oxide Synthase