海藻酸钙作为缓释片的骨架材料的研究

海藻酸钠(NaAl)与可溶性钙盐同时存在干片剂中服后遇胃液即生成酸不溶性海藻酸钙(CaAl)的凝胶骨架,其中所含药物因缓释而具长效作用。用扫描电镜研究了这种骨架并发现NaAl粉末的细度、钙盐的形式及用量、制片工艺、颗粒大小等因素对释药速度均有明显影响。硝酸异山梨醇(ISDN)、普鲁卡因酰胺(P)、苯妥因(DPH)、茶碱(Th)、氯丙嗪(Ch)均可藉CaAl而获得不同程度的缓释作用。着重研究了ISDN长效片,结合到该药的消除速度常数,从工艺方面研究了释药速度t₃₀=50分钟的处方。

CALCIUM ALGINATE AS MATRIX FOR SUSTAINED RELEASE TABLETS

After administration of a tablet containing both sodium alginate and soluble calcium salts, an acid insoluble calcium alginate gel matrix can be formed immediately upon wetting with gastric fluid (Fig 1). The active ingredient contained therein is released gradually and a prolonged-action of the drug can be produced accordingly.Scanning electron micrographs were taken for better understanding the structure of the matrix (Fig2, Fig3). It was found that all the particle size of the sodium alginate powder, the forms and quantities of calcium salts, the tabletting processes and the sizes of the dried granules to be compressed etc. affected the release rate markedly. Several drugs including isosorbide dinitrate, procainamide, phenytoin, chloropromazine, and theophylline were incorporated into the alginate formulations separately. The dissolution rates obtained revealed that sustained release effects were achieved to some degree by this type of tablets (Fig4).In considering the relative short half-life characterized by isosorbide dinitrate (ISDN), efforts were made to develop a satisfactory formulation with a suitable dissolution rate. A formulation with t₃₀ about 50 min. was obtained by using fine powder of sodium alginate (120 mesh) and medium size granules.