This study is looking at 3 different types of enemas used before receptive anal intercourse in men who have sex with men (MSM). We are investigating whether the enemas cause any damage to the lining of the colon, how far up the colon the enemas travel after they are given, and how much study participants like using each of the enemas.

• Drug: Fleets enema
• Drug: tap water enema
• Drug: Normosol-R enema

Inclusion Criteria:

• Male
• ≥ Age of 18
• HIV-1 status antibody negative as documented at screening

• A history of RAI at least twice per month in the prior 3 months*

  • Required to assure that subjects are likely to complete each stage of enema test article use in a reasonable amount of time.
• History of enema use prior to RAI at least some of the time
• Willing to use each study product prior to RAI on 3 separate occasions.
• Willing to refrain from RAI for 48 hours before and after inpatient periods.
• Willing to use condoms for the duration of the study
• Availability to return for all study visits, barring unforeseen circumstances
• Understands and agrees to local STI reporting requirements
• Able and willing to communicate in English
• Able and willing to provide written informed consent to take part in the study
• Able and willing to provide adequate information for locator purposes

Exclusion Criteria:

• Female
• HIV positive at baseline
• History of inflammatory bowel disease
• Active inflammatory condition of the GI tract at baseline
• Active rectal infection at Visit 2 (Infections identified during the screening period must be treated prior to Visit 2)
• Presence of any painful anorectal conditions that would be tender to manipulation. (Participants with hemorrhoids and/or anal warts that are not painful may participate.)
• History of prosthetic cardiac valves, including bioprosthetic and homograft valves, previous bacterial endocarditis, surgically constructed systemic pulmonary shunts or conduits, and complex cyanotic congenital heart disease such as single ventricle states, transposition of the great arteries, tetralogy of Fallot or similar conditions that put the subject at high risk for bacteremia during endoscopy, hence requiring antibiotic prophylaxis.
• Unwillingness to refrain from chronic use of aspirin and NSAIDs.
• Use of warfarin or heparin
• Use of systemic immunomodulatory medications within 72 hours of Visit 2 baseline
• Use of rectally administered medications, including over-the-counter enemas, within 72 hours of Visit 2 baseline
• Use of product containing nonoxyl-9 rectally within 72 hours of Visit 2
• Use of any investigational products within 72 hours of Visit 2 baseline
• Any other clinical condition or prior therapy that, in the opinion of the investigator, would make the patient unsuitable for the study or unable to comply with the study requirements. Such conditions may include, but are not limited to, current or recent history of severe, progressive, or uncontrolled renal, hepatic, hematological, gastrointestinal, endocrine, pulmonary, neurological, cerebral disease, or coagulopathies.