Phosphodiesterase type 5 inhibitors in postprostatectomy erectile dysfunction: a critical analysis of the basic science rationale and clinical application.
BACKGROUND
Erectile dysfunction (ED) after radical prostatectomy (RP) has a significant negative impact on a patient's health-related quality of life. Phosphodiesterase type 5 inhibitors (PDE5-Is) have recently been utilized not only as a treatment of ED in this population but also as a preventive strategy in penile rehabilitation programs.


OBJECTIVE
To elucidate the pathophysiologic mechanisms of post-RP ED, to assess the need for rehabilitation following surgery, and to analyze the basic scientific evidence and clinical applications of PDE5-Is for the prevention and treatment of ED.


METHODS
A systematic review of the literature using Medline, Cancerlit, and the Cochrane Library was conducted for the period between January 1997 and June 2008 using the keywords erectile dysfunction, radical prostatectomy, and phosphodiesterase inhibitors. Efficacy and safety of PDE5-Is in the randomized, placebo-controlled trials are evaluated in this review, and the limitations of the remaining studies are also discussed.


RESULTS
Post-RP ED has many factors. Cavernosal nerve injury induces pro-apoptotic factors (ie, loss of smooth muscle) and pro-fibrotic factors (ie, an increase in collagen) within the corpora cavernosa. Cavernosal changes may also be attributed to poor oxygenation due to hemodynamic changes. Experimental data support the concept of cavernosal damage and suggest a protective role for daily dosage of a PDE5-I; however, similar data have not yet been replicated in humans. Penile rehabilitation programs are common in clinical practice, but there is no definitive evidence to support their use or the best treatment strategy. PDE5-Is are efficacious and safe in young patients with normal preoperative erectile function who have undergone bilateral nerve-sparing radical prostatectomy. On-demand use of a PDE5-I may be at least as efficacious as daily use. PDE5-I use in penile rehabilitation programs is not supported by rigorous level 1 evidence-based medicine.


CONCLUSIONS
PDE5-Is are an efficacious and safe treatment for post-RP ED in properly selected patients. The experimental results on the protective role of daily dosages of PDE5-Is, while robust, have not been replicated in humans. With current human data, the role of a PDE5-I alone as a rehabilitation strategy is unclear and deserves further investigation.
Hatzimouratidis
Konstantinos
K
2nd Department of Urology, Aristotle University, Thessaloniki, Greece. kchatzim@med.auth.gr
Burnett
Arthur L
AL
Hatzichristou
Dimitrios
D
McCullough
Andrew R
AR
Montorsi
Francesco
F
Mulhall
John P
JP
D007172:Erectile Dysfunction / Q000188:drug therapy* / Q000209:etiology / Q000523:psychology / Q000534:rehabilitation; D006801:Humans; D008297:Male; D058986:Phosphodiesterase 5 Inhibitors; D010726:Phosphodiesterase Inhibitors / Q000627:therapeutic use*; D011183:Postoperative Complications / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology; D011468:Prostatectomy / Q000009:adverse effects*; D011788:Quality of Life; D020127:Recovery of Function; D014665:Vasodilator Agents / Q000627:therapeutic use
D058986:Phosphodiesterase 5 Inhibitors; D010726:Phosphodiesterase Inhibitors; D014665:Vasodilator Agents