Effect of oral administration of high‐dose nitric oxide donor l‐arginine in men with organic erectile dysfunction: results of a double‐blind, randomized, placebo‐controlled study

Abstract

Objectives To determine, in a prospective randomized, double‐blind placebo‐controlled study, the effect of 6 weeks of high‐dose (5 g/day) orally administered nitric oxide (NO) donor l‐arginine on men with organic erectile dysfunction (ED). Patients and methods The study included 50 men with confirmed organic ED who were randomized after a 2‐week placebo run‐in period to receive l‐arginine or placebo. A detailed medical and sexual history, O’Leary's questionnaire, a specially designed sexual function questionnaire and a sexual activity diary were obtained for each patient. All participants underwent a complete physical examination including an assessment of bulbocavernosus reflex and penile haemodynamics. Plasma and urine nitrite and nitrate (designated NOx ), both stable metabolites of nitric oxide, were determined at the end of the placebo run‐in period, and after 3 and 6 weeks. Results Nine of 29 (31%) patients taking l‐arginine and two of 17 controls reported a significant subjective improvement in sexual function. All objective variables assessed remained unchanged. All nine patients treated with l‐arginine and who had subjectively improved sexual performance had had an initially low urinary NOx , and this level had doubled at the end of the study. Conclusions Oral administration of l‐arginine in high doses seems to cause significant subjective improvement in sexual function in men with organic ED only if they have decreased NOx excretion or production. The haemodynamics of the corpus cavernosum were not affected by oral l‐arginine at the dosage used.

Lifestyle and metabolic approaches to maximizing erectile and vascular health

“…L-Arginine has been disappointing as a supplement for ED or heart disease, probably because it is extensively metabolized in the gut wall and liver. Only a very large dose (5 g per day) has been reported to have some benefit on ED, 65,66 whereas smaller doses such as 1.5 g are ineffective (although commonly promoted). 67 Response to PDE-5 inhibitors NO causes penile muscle relaxation by increasing cyclic GMP.…”

Improvement of erectile function with Prelox: a randomized, double-blind, placebo-controlled, crossover trial

“…Five grams of Larginine per day improved ED in 31% of patients, whereas 1.5 per day had no better effect than placebo. 2,3 In combination with yohimbine, 3.25 g L-arginine produced only marginal additional improvement. 4 So the effect of L-arginine seems to be weak and dose-dependent.…”

The effects on plasma L-arginine levels of combined oral L-citrulline and L-arginine supplementation in healthy males

“…8) However, relatively large doses of Larginine are required to produce these effects in humans. Approximately 40% of oral L-arginine is metabolized by arginase on the first pass, 9,10) and a further 15% of systemic L-arginine is abstracted and metabolized by the liver.…”