Evaluation of amylose used as a drug delivery carrier.

The enzyme-dependent conjugates of indomethacin and amylose (Am-IND) were synthesized at room temperature using N,N'-dicyclohexylcarbodiimide (DCC) as a coupling agent and 4-(N,N'-dimethylamino) pyridine (DMAP) as a catalyst. Their structures were characterized by FTIR and (1)H NMR analyses, and the results indicated that the IND residues were conjugated with amylose backbones through ester bonds. For the conjugate with a lower IND content, the better water absorption property was advantageous for enzymes diffusing into the swollen conjugate, resulting in biodegradation of the conjugates and release of IND. In vitro biodegradation evaluation indicated that the Am-IND conjugates were biodegraded in the simulated media of the intestines. In vitro drug release experiments showed that the Am-IND conjugates exhibited a sustained release behavior in the simulated media of the intestines, while IND was hardly released in the simulated gastric fluid. These features provide a great opportunity to use the conjugates as a prodrug for intestinally targeted and controlled release of IND through oral administration. This study may lead to the development of effective methods for utilizing amylose as a new drug delivery carrier.