Inclusion Criteria

• Male patients with organ-confined, non-metastatic prostate cancer (stages cT1c-T2c), planning to undergo Robotic-Assisted Laparoscopic Bilateral Nerve Sparing Radical Prostatectomy (NSRP)
• Prostate-Specific Antigen (PSA) levels less than 15 ng/ml (within the last 12 months), with biopsy-proven prostate cancer, for whom postoperative adjuvant therapy (e.g. radiation or androgen deprivation therapy) is not expected to be needed
• Ages 45-75
• An Abridged International Index of Erectile Function-Erectile Function (IIEF-5) score of greater than or equal to 17 at time of screening
• Has experienced at least 6 months of regular sexual activity and sexual activity during the 12 weeks prior to prostate biopsy or surgery
• Willingness to abstain from treatments for Erectile Dysfunction until 3 months after surgery
• Willingness to participate and able to provide informed consent

Exclusion Criteria

• Planned adjuvant therapy after NSRP based on specimen pathology and stage of prostate cancer (stage T3 or greater), positive lymph nodes or positive surgical margins
• Neo-adjuvant therapy prior to NSRP
• History of recurrent prostate cancer
• History of seizures, multiple sclerosis, stroke or any other diagnosed neurological disorder
• History of non-organ confined or metastatic prostate cancer (clinical Stages T3 or greater)
• History of known hypersensitivity to 4AP
• Patients with history of penile surgery other than circumcision or endoscopic urethral stricture surgery
• Renal impairment based on calculated GFR (GFR<60 mL/min)
• Use of any other aminopyridine medications for any other indication