Inclusion Criteria:  Otherwise healthy male subjects with ED as determined from an IIEF-5 score of <16, with a body mass index of 18 to 35 kg/m2 (inclusive), of any ethnic origin.  Subject must have had at least one intent to have sexual intercourse during the last 3 months prior to Screening.  Exclusion Criteria:  Any significant CNS, cardiac, pulmonary, metabolic, renal, hepatic (including Gilbert's syndrome), gastrointestinal (GI) or psychiatric conditions, or history of fainting or syncope or such condition that, in the opinion of the Investigator, may place the subject at an unacceptable risk as a participant in the study, may interfere with the interpretation of safety or tolerability data obtained in this study, or may interfere with the absorption, distribution, metabolism or excretion of drugs, or with the completion of treatment according to this Protocol.  Clinically significant history of abnormal physical or mental health interfering with the study as determined by medical history and physical examinations obtained during Screening or Day -7 as judged by the Investigator (including [but not limited to], neurological, psychiatric, endocrine, cardiovascular, respiratory, GI, hepatic, or renal disorder).  Clinically significant abnormal laboratory results (including hepatic and renal panels, complete blood count, chemistry panel and urinalysis), 12-lead ECG and vital signs, or physical findings at Screening. In case of uncertain or questionable results, tests performed during the Screening visit may be repeated to confirm eligibility or judged to be clinically irrelevant for otherwise healthy subjects with ED.