(A) Plasma TFV, (B) colon TFV, and (C) colon TFV-DP concentrations 15 min after enema dosing. Normal saline (NS) and NS diluted 1:1 with water (1/2 NS) were compared as vehicles. TFV prodrugs were formulated at molar equivalents: TFV (1.76 mg/ml), TDF (3.89 mg/ml), TAF (3.28 mg/ml), CMX157 (3.72 mg/ml). * p < 0.05, ** p < 0.01, *** p < 0.001