INTESTINAL-ABSORPTION OF (-)-CARBOVIR IN THE RAT

(-)-Carbovir (CBV) is a carbocyclic nucleoside analogue with in vitro activity against the human immunodeficiency virus. The sites and mecha nism of absorption of (-)-CBV from the rat small intestine were studie d in the anesthetized male Sprague-DawIey rat. (-)-CBV was perfused th rough either duodenal, jejunal, or ileal segments at three concentrati on levels ranging from 1 to 500 mu g/mL. The fraction remaining to be absorbed at steady-state and the absorptive clearance were calculated for each experiment. The effect of solvent drag on the absorptive clea rance was also investigated. Two-way ANOVA for the absorptive clearanc e per unit length was not significant for either (-)-CBV concentration or site of perfusion. The fraction remaining to be absorbed at steady -state was found to be 0.804 +/- 0.091 (n = 30). A strong correlation was found between the absorptive clearance and the net water absorptiv e flux. The mechanism of (-)-CBV absorption across the rat small intes tine apparently consists of both passive diffusion and convection.