DREAM-01 is an early phase 1, open label, dose-escalation and variable osmolarity study to compare the safety, pharmacokinetics (PK), pharmacodynamics (PD), and acceptability of 3 formulations of a tenofovir (TFV) enema. The goal of the study is to identify the dose and osmolarity of a TFV enema for human immunodeficiency virus (HIV) pre-exposure prophylaxis (PrEP) which achieves the desired colonic mucosal mononuclear cells (MMC) tenofovir diphosphate (TFV-DP) target concentrations that have previously been shown to confer protection from HIV acquisition in men who have sex with men (MSM).