Investigation of a complex plant extract for mild to moderate erectile dysfunction in a randomized, double-blind, placebo-controlled, parallel-arm study

BJU Int. 2010 Oct;106(7):1030-3. doi: 10.1111/j.1464-410X.2010.09213.x. Epub 2010 Feb 22.


Objective: To assess the effects of a complex plant extract (Prelox®, a formulation of pine bark extract and l-arginine aspartate; Horphag Research UK Ltd, London, UK) on erectile dysfunction (ED) in men, as sexual desire typically persists in ageing men, while their erectile and endothelial function gradually declines.

Patients and methods: In this double-blind, placebo-controlled study we assessed the effects of Prelox in 124 patients (aged 30-50 years) with moderate ED over an investigational period of 6 months. The International Index Of Erectile Function (IIEF) was used to quantify changes in sexual function.

Results: The erectile domain of the IIEF (questions 1-5 plus 15) improved with Prelox from a baseline mean (sd) score of 15.2 (6.6) to 25.2 (2.1) after 3 months and 27.1 (2.1) after 6 months of treatment. In the placebo group there was an increase from a baseline score of 15.1 (7.0) to 19.1 (3.0) and 19.0 (3.1) after 3 and 6 months, respectively. The effects with Prelox were statistically significant compared with placebo (P < 0.05). Mean (SD) total plasma testosterone levels increased significantly from 15.9 (2.3) to 18.9 (2.6) nmol/L (P < 0.05) after 6 months with Prelox, compared to an increase from 16.9 (2.4) to 17.3 (2.3) nmol/L in the placebo group.

Conclusion: This study shows that Prelox is effective for improving erectile function, and that this effect persists on continuous therapy for up to 6 months. Moreover, there is some evidence that erectile function continues to improve the longer the therapy is used.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Arginine / therapeutic use*
  • Aspartic Acid / therapeutic use*
  • Drug Combinations
  • Drug Therapy, Combination
  • Epidemiologic Methods
  • Flavonoids / therapeutic use*
  • Humans
  • Impotence, Vasculogenic / drug therapy*
  • Male
  • Middle Aged
  • Phytotherapy*
  • Pinus
  • Plant Extracts / therapeutic use*
  • Treatment Outcome
  • Vasodilator Agents / therapeutic use*


  • Drug Combinations
  • Flavonoids
  • Plant Extracts
  • Vasodilator Agents
  • prelox
  • Aspartic Acid
  • pycnogenols
  • Arginine
  • arginine aspartate