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 .
Early combination therapy: intracavernosal injections and sildenafil following radical prostatectomy increases sexual activity and the return of natural erections
Early pharmacological prophylaxis has been reported to increase the return of spontaneous erections following radical prostatectomy ( RP ) . In this study , we evaluated the role of intracavernosal alprostadil ( PGE1 ) combined with sildenafil in stimulating early recovery of spontaneous erections following RP . In this prospect i ve study , we included 22 patients who underwent bilateral nerve-sparing RP after October 2004 .  Sildenafil dose of 50 mg/day was started at the time of hospital discharge . Of 22 patients , 18 started on PGE1–4 μg ( 1–8 ) and four started on low-dose Trimix ( 20 U ) 2–3 times/week . These patients are followed up at regular intervals ( 3 , 6 , 9 and 12 months ) with abridged version of the International Index for Erectile Function-5 question naire . Patient compliance , return of sexual activity and return of natural erection , adverse effects and reasons for discontinuation were recorded . Penile doppler studies were performed during followup visits to assess the vascular status . After a mean followup of 6 months ( 3–8 months ) , 11/22 ( 50 % ) patients had return of spontaneous partial erections . Of the 18 PGE1 users , six continued 4 μg PGE1 , four increased the dose to 8 μg , six decreased the dose to 2 μg and two patients further reduced the dose to 1 μg . Of four low-dose Trimix users , three increased the dose to 30 U and one reduced the dose to 15 U. Of 22 patients , 21 were sexually active : 12/21 ( 57 % ) with the injections alone and 9/21 ( 42.9 % ) with combination therapy ( injections ( PGE1 ) and sildenafil ) . Penile doppler studies revealed arterial insufficiency in 77 % ( 17/22 ) patients and venous insufficiency in one patient . Early intracavernosal injections following RP facilitated early sexual intercourse , patient satisfaction and potentially earlier return of natural erections . Early combination therapy with sildenafil allowed a lower dose of intracavernous injections , minimizing the penile discomfort
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 .