The new immunosuppressive agent, SDZ-RAD, and its analog rapamycin were examined for intestinal absorption, metabolism, and bioavailability in Wistar rats. Intestinal first-pass metabolism studies from rat jejunum showed that at 0.5 mg of SDZ-RAD/kg rat, 50% of the parent compound was metabolized in the intestinal mucosa, and this decreased to around 30% when SDZ-RAD was increased to 5.0 mg/kg ...