Application of microencapsulation for toxicology studies. III. Bioavailability of microencapsulated cinnamaldehyde.

The bioavailability of microencapsulated cinnamaldehyde (CNMA) was investigated in male F344 rats. Rats were gavaged with CNMA in corn oil using either microencapsulated or the neat chemical at doses of 50, 250, and 500 mg/kg. No differences between the two formulations at any of the doses were found in either CNMA blood concentration profiles or in the rate of urinary hippuric acid excretion. Both formulations showed a low bioavailability (< 20%) at 250 and 500 mg/kg. Regardless of the formulation used, oral gavage of CNMA significantly increased the urinary excretion of hippuric acid. About 75% of the dose of CNMA was metabolized to hippuric acid and recovered in the urine. The total amount of hippuric acid recovered in a 50-hr urinary collection correlated well with the CNMA dose. The data suggest that there was complete release of CNMA from the microcapsules and that microencapsulation of CNMA does not affect its bioavailability or its metabolism. Since CNMA microcapsules are stable in rodent diet, the microencapsulation of CNMA, and perhaps other labile chemicals, will prevent degradation and facilitate the testing of such compounds in toxicology studies.