[Studies on the pharmacokinetics of C-14 cinnamic-acid derivatives in rats]

Using some 14C-labelled derivatives of cinnamic acid which are of interest as metabolites of chlorogenic acid we studied their pharmacokinetic behaviour in rats. The absorption rate constant from intestinal was 2--10 times greater than the elimination rate constant. After i.v. application the half life of elimination from the blood was between 13 and 37 minutes. When greater amounts (50 mg/kg) were given by i.d. application, absorption and elimation were delayed. The tested compounds were excreted mainly by the kidneys and most of the given dosis could be found in urine within 2 hours. The biliary excretion differed widely among the tested compounds: only up to 3% were excreted in the bile in the case of m-cumaric acid, p-cumaric acid and caffeic acid, whereas up to 30% were found when ferulic acid or trimethoxycinnamic acid were given. From these results a greater ole of caffeic acid in the enterohepatic circulation is not to be expected.