Safety and Efficacy of YHD1023 in Erectile Dysfunction

Inclusion Criteria: * Male volunteers of aged 20 years and older with history of organic erectile dysfunction of at least 6 months duration * Anticipate having the same adult female sexual partner, who have no possibility of being pregnant or breast-feeding and take steps to prevent conception during the study * The patient or legally authorized representative must sign a written informed consent, prior to the any procedure, using a form that is approved by the local Institutional Review Board after detail explanation of the purpose, contents, and characteristic of the drug * Have Erectile Function(EF) domain score 25 and under as the result of the International Index of Erectile Function(IIEF) * Agree to make at least 4 sexual intercourse attempts on 4 separate days with the female sexual study party during the 4-week run-in period without medication and at least 50% of attempts during this period had been unsuccessful due to insufficient erection or unable to sustain penile rigidity until ejaculation Exclusion Criteria: * Have history of stroke, myocardial infarction, or Coronary Artery Bypass Graft surgery within the last 6 months * Have history of cardiac failure, unstable angina, or life-threatening arrhythmia within the last 6 months * Shown tachyarrhythmia, heart rate over 100 times/min(e.g. arterial fibrillation, flutter) * Presence of hypotension as evidenced by SBP/DBP \< 90/50mmHg or uncontrollable hypertension as evidenced by SBP/DBP \> 170/100mmHg * Presence of diagnosed diabetes(HbA1C \> 12%) * Have history of symptomatic postural hypotension within the last 6 months * Have history of spinal cord injury, radical prostatectomy, or pelvic surgery * Presence of penile anatomical deformities (e.g. severe penile fibrosis or Peyronie's disease) * Presence of hypogonadism(serum total testosterone under the reference lowest limit) * Presence of hepatic impairment(AST or ALT \> 3 times of normal upper limit) or renal impairment(serum creatinine ≥ 2.5mg/dl) * Have history of severe gastrointestinal hemorrhage within the last 1 year * Have history of hematodyscrasia predisposing to priapism(e.g. sickle cell disease, multiple myeloma, or leukemia) or bleeding disorder * Subject who is judged to be ineligible according to their physical checkup(medical history, physical examination, ECG, laboratory values and etc.) within 56 days prior to the first administration * Concomitant use of one or more of nitrates/nitric oxide(NO) donor(e.g. nitroglycerine, isosorbid, mononitrate, isosorbid dinitrate, amylnitrate/nitrite, sodium nitroprusside), Trazodone, cancer chemotherapy, anticoagulants, androgens, or anti-androgens * Use of any PDE-5 inhibitor(e.g. Viagra, Levitra, Cialis, Yaila, or Zydena), vasodilator self-injection, or other treatments for erectile dysfunction within the last 2 weeks prior to the study * Participated in any other clinical trials within 30 days prior to the first administration * Have history of primary hypoactive sexual desire * Subject who is judged to be ineligible by principal investigator or sub-investigator due to mental disorder or continuous drug abuse