• The primary objective is to determine the proportion of HIV-positive subjects experiencing relief of diarrhea with crofelemer compared to placebo during the placebo-controlled treatment phase. [ Time Frame: 31 days ] [ Designated as safety issue: No ]
• Primary efficacy outcome is two or less watery bowel movements per week during at least two weeks of the treatment phase. [ Time Frame: 31 days ] [ Designated as safety issue: No ]

This is a randomized, double-blind, parallel-group, placebo-controlled, multi-center study. This study will compare an investigational new drug (crofelemer) to placebo for the control of HIV-associated diarrhea. The first stage of the study will determine the optimal dose of study drug based on safety and response to therapy and the second stage will evaluate further the effectiveness of the optimal dose.

• Drug: Placebo
• Drug: Crofelemer 125 mg
• Drug: Crofelemer 250 mg
• Drug: Crofelemer 500 mg

Inclusion Criteria:

• History of HIV-1 infection confirmed by standard serological tests
• Stable medical regimen for treatment of HIV disease and associated conditions for at least 4 weeks prior to screening
• Patient-reported history of diarrhea, defined as either persistently loose stools despite regular ADM use, or one or more watery bowel movements per day without regular ADM use, of at least 1 month duration
• Colonoscopy within the past 5 years if ≥ 50 years of age.

Exclusion Criteria:

• Pregnancy or breast-feeding
• Current or past gastrointestinal (GI) medical or surgical conditions
• Use of certain opiate pain medication within 2 weeks of screening
• Use of an antibiotic within 2 weeks prior to screening, with the exception of stable antibiotic therapy for prophylactic treatment of infection or an HIV-associated condition
• CD4 counts < 100 cells/mm3
• Previous randomization into this study, or into any other crofelemer study