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 .
Recovery of spontaneous erectile function after nerve-sparing radical retropubic prostatectomy with and without early intracavernous injections of alprostadil: results of a prospective, randomized trial.
PURPOSE This study was aim ed at assessing prospect ively the effect of postoperative intracavernous injections of alprostadil on the recovery of spontaneous erectile function after nerve-sparing radical retropubic prostatectomy . MATERIAL S AND METHODS A total of 30 potent patients with clinical ly localized prostate cancer ( clinical stage B1 or B2 , Gleason sum 7 or greater , prostatic specific antigen less than 20 ng./ml . ) underwent nerve-sparing radical retropubic prostatectomy  and was subsequently r and omized to alprostadil injections 3 times per week for 12 weeks ( group 1 , 15 patients ) or  observation without any erectogenic treatment ( group 2 , 15 patients ) . Patients were assessed at the 6-month followup by sexual history , physical examination , color Doppler sonography of the cavernous arteries and polisomnographic recording of nocturnal erections . RESULTS In group 1 , 12 patients ( 80 % ) completed the entire treatment schedule and were evaluated at the long-term followup . Eight patients in this group ( 67 % ) reported the recovery of spontaneous erection sufficient for satisfactory sexual intercourse , compared with 3 patients ( 20 % ) in group 2 . The difference between the 2 groups was statistically significant ( p < 0.01 ) . In group 1 , all but 1 patient reporting normal postoperative erections also showed normal erections at nocturnal testing , whereas color Doppler sonography demonstrated normal penile hemodynamics in all of them . In these patients , failures were the result of cavernous veno-occlusive dysfunction ( 2 cases , 17 % ) and cavernous nerve injury ( 2 cases , 17 % ) . In group 2 , patients with normal erections showed both normal nocturnal testing and penile hemodynamics , whereas failures were the result of cavernous veno-occlusive dysfunction ( 8 cases , 53 % ) , cavernous arterial insufficiency ( 2 cases , 13 % ) or cavernous nerve injury ( 3 cases , 20 % ) . Complications in patients treated with alprostadil injections accounted for 2 cases ( 13 % ) of a penile nodule and 1 further case ( 6 % ) of prolonged penile erection . Complications were not seen in group 2 patients . CONCLUSIONS Early postoperative administration of alprostadil injections significantly increases the recovery rate of spontaneous erections after nerve-sparing radical retropubic prostatectomy . It is our belief that programmed vasoactive injections improve cavernous oxygenation , thereby limiting the development of hypoxia-induced tissue damage . The potential complications related to the use of intracavernous injections must be clearly explained to patients
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 .