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-dem and 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 .
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 .
CONTEXT  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 eluci date 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 .
EVIDENCE SYNTHESIS 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 .
Role of sildenafil citrate in treatment of erectile dysfunction after radical retropubic prostatectomy.
BACKGROUND Sildenafil citrate was introduced as a treatment for  erectile dysfunction  in April 1998 in the United States and has been available since March 1999 in Japan . In this article , we assess the efficacy of sildenafil in the treatment of  erectile dysfunction in Japanese men after radical retropubic prostatectomy for localized prostate cancer . METHODS Of 106 men who underwent radical retropubic prostatectomy between January 1994 and March 2000 , 43 were prescribed sildenafil at their request after radical retropubic prostatectomy .  Medication was initiated at 25 mg , and if this was ineffective , the dose was increased to 50 mg . Of the patients , 18 underwent bilateral and 21 unilateral nerve sparing ( NS ) procedures , while in 4 patients , a non-NS procedure was performed . These patients were interviewed using a question naire about their response to sildenafil and using the 5-item International Index of Erectile Function ( IIEF-5 ) question naire . RESULTS Thirty-three of the 43 patients were eligible for evaluation of the  efficacy of sildenafil and 27 completed the IIEF-5 question naires . Sildenafil at 50 mg had a better effect on sexual function than 25 mg in most Japanese patients . Of the 16 patients who underwent bilateral NS procedures , 10 ( 62.5 % ) had improved ability for intercourse and 3 ( 18.8 % ) had improved erections . Of the 13 patients who underwent unilateral NS procedures , 7 ( 53.8 % ) had improved ability for intercourse and 4 ( 30.8 % ) had improved erections . None of the 4 patients who underwent non-NS procedures had a positive response . Of 24 patients with positive response to sildenafil , 3 ( 12.5 % ) did not have to take sildenafil after receiving it because they did not require it for intercourse . Mean IIEF-5 score increased from 4.3 to 11.4 ( P < 0.0001 ) . Patient age , time since surgery , PSA and pathological stage did not have statistically significant effects on outcome . The most commonly cited adverse effect was headache ( 21 % ) . CONCLUSION Sildenafil is equally effective for erectile dysfunction in Japanese patients who have undergone bilateral and unilateral NS procedures , and aids recovery of natural erectile function after radical retropubic prostatectomy . However , non-NS procedure patients had no response to sildenafil . This study suggested that sildenafil is well tolerated and should be initially used for treatment of Japanese men with erectile dysfunction  after radical retropubic prostatectomy
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-dem and 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 .
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 .
CONTEXT  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 eluci date 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 .
EVIDENCE SYNTHESIS 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 .