- Required treatment with calcium channel, beta-blocker medication, nitrates, or anti- epileptic drugs; d) Poorly controlled diabetes mellitus as defined by HgA1c > 8.0 mg% at time of enrollment; e) Change in medication for diabetes or hypertension within 2 months of study enrollment; f) Gonadal failure (testosterone < 200 ng/dl) not treated with hormone replacement; g) History of malignancy except non-melanomatous skin cancers h) A life expectancy of less than 12 months; i) An indwelling urethral catheter; j) A prior penile prosthetic implant l) Received an investigational drug, investigational therapy, or other form of ED therapy, including approved treatments, within the past 30 days; m) Peyronie's disease; n) Any screening laboratory values outside of the normal laboratory range as defined by the central laboratory normal ranges and in the judgment of the investigator is considered clinically significant (hepatic biochemical markers [AST, ALT, GGT, alkaline phosphatase, and bilirubin] > twice the upper limit of the normal reference range may be accepted with written consent of the sponsor). o) Any clinically significant ECG abnormality NOTE: Sinus bradycardia of 50-59 bpm is permissible. Other abnormalities that can be normal variants (and considered clinically insignificant) may be permissible. However, participants with such abnormalities cannot be randomized without review of their medical history and prior written approval of the sponsor (or designee).