OBJECTIVE To fabricate curcumin-loaded enteric nanofibers, investigate their release behavior in vitro and pharmacokinetics in rats.

METHODS A series of curcumin-loaded Eudragit nanofibers were prepared by electrospinning using Eudragit L100-55 as the polymer matrix, with the addition of a certain amount of curcumin and with/without a small amount of adjuvant piperine and surfactant TPGS. The morphology and thermal stability of the drug-loaded fibers were characterized, and the physical status of drugs in fibers was determined. The contents of curcumin and piperine were determined by HPLC, and the drug loading and entrapment efficiency of the fibers were calculated. The in vitro drug release of the fibers was investigated by the paddle method using a dissolution tester. The plasma drug concentration was determined by HPLC after oral administration of the drug-loaded fibers in rats, and the pharmacokinetic parameters were processed and analyzed by DAS 2.0 software.

RESULTS The drug-loaded fibers had uniform structures, good thermal stability, controllable drug loading, and high entrapment efficiency. Drugs were dispersed in fibers in amorphous state. Small amount of curcumin were released from these fibers in the simulated gastric fluid of pH 1.2, while in the simulated intestinal fluid of pH 6.8 most of the drug were released. The peak time T_max of the free curcumin group was 30 min, while T_max of the drug-loaded fiber groups were 180 min. The peak concentration C_max of the drug-loaded fiber groups S-2 (loaded with curcumin), S-3 (loaded with curcumin and a small amount of TPGS) and S-4 (loaded with curcumin as well as a small amount of piperine and TPGS) were 3.8, 8.8 and 10.5 times higher than that of the free curcumin group, respectively. The relative bioavailability of curcumin for S-2, S-3 and S-4 were 1 152%, 2 859% and 3 772%, respectively.

CONCLUSION The curcumin-loaded Eudragit nanofibers can be used as enteric formulations to achieve intestinal-targeted delivery and release of curcumin. The fibers can increase the oral absorption and significantly improve the oral bioavailability of curcumin. The addition of a small amount of piperine and TPGS to the curcumin-loaded nanofibers can further improve the bioavailability by a big margin.