Phase 2a Topical Sildenafil Proof-of-Concept Study in Men With Mild to Moderate ED

Inclusion Criteria: 1. Patient is a heterosexual male ≥ 18 and ≤ 70 years of age. 2. Patient has had a clinical diagnosis of erectile dysfunction for a minimum of 6 months. 3. Patient has a body mass index (BMI) from 18 to 30 kg/m², inclusive. 5\. Patient is capable of understanding and complying with the protocol and agrees to sign the informed consent document. 6 Patient agrees to use condoms with sexual activity for 7 days immediately following each visit that involves application of SST-6006 or placebo cream (i.e. Visit 2, Visit 4 and Visit 5). 7\. Patient has a testosterone level ≥ 300 ng/dL (either naturally or through androgen replacement therapy; if on androgen replacement therapy, must have been taking for ≥ 6 months). 8\. Patient is willing to undergo plethysmography procedure with VSS during the trial \- Exclusion Criteria: Subject is unfamiliar with or unwilling to watch visual sexual stimulation (VSS). 2\. Subject has any disorder or a history of any disorder that may prevent the successful completion of the study. 3\. Subjects with an abnormal physical exam, that in the opinion of the Investigator, would interfere with study participation. 4\. Subject has a significant cardiovascular, hepatic, renal, respiratory, gastrointestinal, endocrine, immunologic, dermatologic, hematologic, neurologic, genitourinary, or psychiatric disease or other unstable medical condition that would contraindicate administration of study medication, interfere with study evaluation, limit study participation, contraindicate sexual activity, or confound the interpretation of study results. 5\. Subject has an active ulcer or clinically significant bleeding disorder. 6. Subject has a history of myocardial infarction, stroke, or life-threatening arrhythmia within 6 months prior to Visit 1; a history of coronary disease causing angina; or congestive heart failure requiring medical intervention. 7\. Subject has uncontrolled hypertension or untreated hypertension. 8. Subject has a history of orthostatic hypotension or orthostatic hypotension. 9\. Subject is unable to walk up and down two flights of stairs briskly without chest pain. 10\. Subject is using alpha blockers. 11. Subject is using or has possession of nitrate containing medication(s). 12. Subject has retinitis pigmentosa or sickle cell anemia or related anemias, even if the subject feels clinically well at the time of screening. Subjects with retinitis pigmentosa will be identified by specifically asking whether they have the condition, if there are visual signs and symptoms of the condition (including questioning subjects as to whether they have difficulty seeing at night or in low light, and if they have any visual field deficits that indicate a loss of peripheral or central vision), or if there is a family history. 13\. Subject has anatomical deformation of the penis such as angulation, cavernosal fibrosis, or Peyronie¡-s disease, or history of genital surgery. 14\. Subject has a history of prostate surgery. 15. Subject has a history of pelvic radiation. 16. Subject has type 1 or type 2 diabetes. 17. Subject has a history of cancer other than basal cell carcinoma. 18. Subject has any surgical or medical condition that may interfere with the absorption, distribution, metabolism, or excretion of the test article. 19\. Subject has a history of drug abuse within 1 year before Visit 1. 20. Subject has a history of alcoholism within 1 year before Visit 1, admitted alcohol abuse, or has an average consumption of more than 2 standard units of alcohol per day (a standard unit equals 12 ounces of beer, 1¨ö ounces of 80-proof alcohol, or 6 ounces of wine). 21\. Subject has had treatment currently or within 1 month (28 days) of Visit 1 with any of the following: weak, moderate, and strong inhibitors and inducers of CYP3A4 and CYP2C9 enzymes (e.g., CYP3A4: ketoconazole, clarithromycin, verapamil, diltiazem, St. John¡-s Wort / CYP2C9: fluconazole, oxandrolone, fluvastatin, and metronidazole). Any prescription, over-the-counter (OTC) medications, or herbal products taken recently or currently being taken will be screened by study personnel prior to study enrollment to confirm such drugs do not inhibit or induce the two enzymes listed above. If the subject takes any prescription or OTC drugs at the direction of a health care provider that are inhibitors or inducers of CYP3A4 and CYP2C9, that provider should be consulted before medications are stopped for the purposes of study participation. 22\. Subject is unwilling to refrain from using any medication for erectile dysfunction, with the exception of study medication, after Visit 1 and throughout the duration of the study up until the completion of Visit 5. 23\. Subject has positive findings from urine drug screen (e.g., amphetamines, barbiturates, benzodiazepines, cannabinoids, cocaine, methadone, and opiates). 24\. Subjects with a positive alcohol breath test. 25. Subject participated in any clinical research study evaluating another investigational drug or therapy within 30 days before the Visit 1. 26\. Subject is unwilling to refrain from ingesting grapefruit, grapefruit-containing products, Seville oranges, or products containing Seville oranges (e.g., orange marmalade) three days prior to each dosing visit. 27\. Subject has any skin breaks, irritation, dermatoses, or lesions in the penile area to which the study cream will be applied. 28\. Subject has a known hypersensitivity or allergy to any of the ingredients in the IP. 29\. Subject has a significant cardiovascular, hepatic, renal, respiratory, gastrointestinal, endocrine, immunologic, dermatologic, hematologic, neurologic, genitourinary, or other unstable medical condition indicated by the laboratory results that would contraindicate administration of study medication, interfere with study evaluation, limit study participation, contraindicate sexual activity, or confound the interpretation of study results. 30\. Subjects who have abnormal laboratory parameters that, in the opinion of the Investigator, could confound interpretation of the study results. 31\. Subjects who have positive serology findings for a sexually transmitted infection (i.e. syphilis, gonorrhea, chlamydia, HIV antibodies, hepatitis b surface antigen (HBsAg) or hepatitis c (HCV) antibodies. 32\. Subjects with abnormal vital signs and/or ECG results that, in the opinion of the Investigator, would affect the interpretation of study results.