Synthesis and application of poly(ethylene-co-vinylalcohol-graft- acetylsalicylic acid) in drug delivery domain

摘要

A series of poly(vinylalcohol-co-ethylene-graft-acetylsalicylic acid) hydrogel (H _i) of different acetylsalicylic acid (AcSa) contents were prepared by grafting of AcSa groups to poly(vinylalcohol-co-ethylene) in an esterification reaction and then crosslinking with oxalic acid. The H _i was characterized by the solubility test, DSC, NMR, and SEM analyses. The AcSa released by retroesterification of H _i at 37°C and at different pHs during 92 h. The results revealed that the amount of AcSa released from H _i depended on the initial content of AcSa in H _i and the pH of the media. In general, the results revealed that the PEVA-graft-AcSa (H _2), which contained initially 1.59 mg of AcSa, released at pH 1 a lower amount of AcSa (0.08 ± 0.02 wt of AcSa/h), stable during the longest period (85 h). On the reverse H _3 which contained 2.05 mg of AcSa presented a highly efficient release rate at pH 7. This hydrogel was able to release 0.80 ± 0.05 wt of AcSa/h, stable for about 60 h. From the first view, this finding seemed to be very important in the drug-release domain, because the hydrogel prepared in this work was able to release a greatest amount of aspirin directly into the intestines (neutral pH).