Distribution of chlorpromazine in the gastrointestinal tract of the rat and its effect on absorptive function.

The distribution of [14C]chlorpromazine was studied in segments of the gastrointestinal tract of the rat after an oral dose of 20 mg/kg (1-2 muc). The total radioactivity in the gastrointestinal tract was, respectively, 43.2 +/- 3.6, 28.9 +/- 2.2 and 14.1 +/- 1.1 (mean +/- S.E. percent administered dose) at 2, 6 and 24 hours after dosing. The maximum observed total radioactivity in the different segments occurred at different times after dosing. The percentage of total radioactivity present in each tissue as unchanged [14C]chlorpromazine decreased with time in all the tissues. At all time points, this parameter also showed a consistent pattern: % stomach greater than % duodenum greater than % jejunum greater than % ileum. The effect of chronic administration of [14C]chlorpromazine on intestinal absorptive function was studied by the everted sac technique. Mucosal transport of L-[14C]methionine was significantly inhibited (24.4% of control), but no effect on transport of D-[14C]xylose was observed.