Kofuji K, Ito T, Murata Y, Kawashima S
Faculty of Pharmaceutical Sciences, Hokuriku University, Kanazawa, Japan.
Chem Pharm Bull (Tokyo). 2000 Apr;48(4):579-81. doi: 10.1248/cpb.48.579.
Chitosan (CS) forms a gel in solutions with a pH above 12, and the gelation occurs at pH of about 9 in 10% amino acid solutions. In this paper, we investigated the enzymatic degradation and the drug release profile of this novel CS gel beads. The degradability of the CS gel beads was affected by the CS properties, e.g. the degree of deacetylation. The release of prednisolone (PS), as a model drug, from the CS gel beads was sustained significantly compared with the gel prepared with NaOH only. However, the release was not able to be sustained by the increment of NaOH concentration in the solution employed for the preparation of CS gel beads. We also investigated the control of drug release from CS gel beads by application of a complex formed between chondroitin sulfate (Cho) and CS. The release of PS from the CS gel beads treated with Cho was prolonged, and the release pattern was not affected by the treatment time. The time to 50% drug release was about 5 min with PS powder, about 200 min in CS gel beads with 10% glycine (Gly) (pH 9.0), and about 330 min in the CS gel beads with 10% Gly (pH 9.0) treated with Cho. Thus CS gel beads appear promising as a vehicle for sustained drug delivery, and the degradation of CS gel beads may be controlled by the degree of deacetylation of CS.
壳聚糖（CS）在pH值高于12的溶液中形成凝胶，在10%氨基酸溶液中，凝胶化发生在pH约为9时。在本文中，我们研究了这种新型CS凝胶珠的酶促降解和药物释放特性。CS凝胶珠的降解性受CS特性的影响，例如脱乙酰度。作为模型药物的泼尼松龙（PS）从CS凝胶珠中的释放与仅用NaOH制备的凝胶相比显著持续。然而，在用于制备CS凝胶珠的溶液中，NaOH浓度的增加并不能维持释放。我们还研究了通过应用硫酸软骨素（Cho）和CS形成的复合物来控制CS凝胶珠中药物的释放。用Cho处理的CS凝胶珠中PS的释放延长，且释放模式不受处理时间的影响。PS粉末50%药物释放时间约为5分钟，含10%甘氨酸（Gly）（pH 9.0）的CS凝胶珠中约为200分钟，用Cho处理的含10% Gly（pH 9.0）的CS凝胶珠中约为330分钟。因此，CS凝胶珠作为持续药物递送的载体似乎很有前景，并且CS凝胶珠的降解可能受CS脱乙酰度的控制。
