海藻酸钙凝胶微丸作为口服缓释给药载体的研究

将海藻酸钠溶液滴入胶凝剂氯化钙溶液中制备了海藻酸钙凝胶微丸。以胶凝过程中凝胶微丸重量变化 (失水量 )研究了胶凝速率及不同浓度海藻酸钠溶液 ( 1 %～ 4 % )与氯化钙溶液 ( 0 0 5～0 2 0mol/L)对胶凝速率的影响 ,结果是 6h前胶凝速率快 ,随后减慢 ,约 70h胶凝完全 ,氯化钙溶液的浓度≥ 0 1mol/L对胶凝速率无明显影响。干燥的凝胶微丸在不同水性介质中溶胀试验结果表明 :在温度约 37℃时 ,微丸在蒸馏水和 0 1mol/L盐酸 ( pH1 0 )中几乎不溶胀 ,而在磷酸盐缓冲溶液( pH6 8)中1h溶胀 ,溶胀后的微丸直径是干燥前湿微丸直径的 1 80 %。海藻酸钙凝胶微丸这种溶胀的 pH敏感性 ,使它能成为口服药物缓释制剂的载体。以硝苯地平为模型药物制备的海藻酸钙凝胶微丸 ,其体外释放试验结果 ,2h累积释放量为 2 0 %～ 30 % ,6h为 6 0 %～ 80 % ,1 2h时大于85 %。药物从微丸中的释放是以扩散和骨架溶蚀相结合的方式。由此可见 ,硝苯地平的海藻酸钙凝胶微丸具有缓释作用

Study on calcium alginate gel beads as oral drugs administration carriers

Ca alginate gel beads were prepared by dropping Na alginate solution into CaCl 2 solution.The gelation rate of the beads were measured in terms of weight changes.The effect of Na alginate concentration (1%～4%) and CaCl 2 solution concentration( 0 05 ～ 0 20 mol/L ) on the gelation rate were studied.The result indicated a rapid initial decrease and a subsequnent slow stage and the higher CaCl 2 solution concentration( ≥0 1 mol/L ) was not obvious.The swelling property of the dried beads from fully cured hydrogels was studied.It should be noted here that no swelling was observed in the distilled water and 0 1 mol/L HCl(pH 1 0) solution,while in phosphate buffer (pH 6 8) the dried beads swelled to the diameter 180% as long as its original diameter before being dried.Such a pH sensitive swelling property could be advantageous to orally administered drug vehicles.Nifedipine (NP) sustained release beads were prepared with calcium alginate as a carrier.The release amount of NP from the beads in vitro was 20%～30% at 2 h ,60%～80% at 6 h ,greater than 85% at 12 h .The NP release from the gel beads followed the mechanism of diffusion and erosion.