Efficacy Study of RX-10100 to Treat Erectile Dysfunction (ED)

Inclusion Criteria: * Have had ED for at least six months * Stable, heterosexual relationship for at least 3 months * Make at least one attempt of sexual intercourse per week during the untreated, 2-week screening period * At least 50% of attempts of sexual intercourse during the untreated baseline period must be unsuccessful * 'Moderate' or 'mild to moderate' ED, defined as an IIEF-EF domain score between 11 and 21 measured Exclusion Criteria: * Following previous or current medical conditions * Any unstable medical, psychiatric, or substance abuse disorder * Penile anatomical abnormalities * Primary hypoactive sexual desire * Spinal cord injury * Hypogonadism * Surgical prostatectomy * Stable or unstable angina pectoris * Myocardial infarction, stroke, or life-threatening arrhythmia * Uncontrolled atrial fibrillation/flutter at screening * Severe chronic or acute liver disease * Moderate or severe hepatic impairment * Clinically significant chronic hematological disease * Bleeding disorder * Significant active peptic ulcer disease * Resting hypotension or hypertension * Malignancy (cancers) * NYHA Class II to IV heart failures * Positive test for Hepatitis B surface antigen (HBsAg) or Hepatitis C * Symptomatic postural hypotension * Following concomitant medication * Androgens or estrogens * Anti-androgens * Potent inhibitors of cytochrome P450 3A4 * Any other investigational drug within 30 days before Visit 1 * Any treatment for ED within 7 days before Visit 1 or during the study * Antibiotics in the penicillin class * Following abnormal laboratory values * Serum total testosterone level (at least 25% lower) * Serum creatinine (\> 3.0 mg/dl) * Elevation of AST and/or ALT (\> 3 times the upper limit of normal) * Diabetic subjects with an HbAlc (\> 6.5%) * Subjects with known hypersensitivity to amoxicillin * Subjects with a history of unresponsiveness to any PDE5 Inhibitor treatment or a history of significant side effects leading to its treatment discontinuation