Introduction and objectives: To systematically analyze and review the available evidence about the potential role of chronic administration of phosphodiesterase type 5 (PDE-5) inhibitors for the cure of erectile dysfunction (ED) based on clinical and basic science data.
Methods: Analysis of published full-length papers that were identified with Medline and Cancerlit from January 1993 to September 2005. Abstracts published in the journals European Urology, the Journal of Urology, the International Journal of Impotence Research, and the Journal of Sexual Medicine as official proceedings of internationally known scientific societies held in the same time period were also assessed.
Results: Chronic administration of PDE-5 inhibitors have reportedly been associated with increased persistent vascular and endothelial function--which represents a key factor in maintaining vascular tone and inducing vasodilation--by increasing the level of endothelial cGMP generated by activation of endothelial nitric oxide. Clinical studies have revealed a potential protective role of these compounds on endothelial function in short- and long-term assessments. Several studies based on animal models have provided direct experimental support for the role of PDE-5 inhibitors in improving the structure and function of the cavernosal tissue and have suggested potential molecular mechanisms involved.
Conclusions: Although evidence increasingly supports the potential role of chronic administration of PDE-5 inhibitors for improving erectile function in patients affected by ED, long-term data are lacking. However, data available from animal models support the evidence of potential benefits induced on endothelial function by chronic exposure to PDE-5 inhibitors.