Pandya N, Pandya M, Bhaskar V H
Department of Pharmaceutics, M.P. Patel College of Pharmacy, Jeevanshilp Campus, Kapadwanj, Gujarat - 387 620, India.
J Young Pharm. 2011 Apr;3(2):97-104. doi: 10.4103/0975-1483.80292.
Floating microspheres have been utilized to obtain prolonged and uniform release of drug in the stomach for development of once-daily formulations. A controlled-release system designed to increase residence time in the stomach without contact with the mucosa was achieved through the preparation of floating microspheres by the emulsion solvent diffusion technique, using (i) calcium silicate (CS) as porous carrier; (ii) glipizide, an oral hypoglycemic agent; and (iii) Eudragit(®) S as polymer. The effects of various formulations and process variables on the internal and external particle morphology, micromeritic properties, in vitro floating behavior, drug loading, and in vitro drug release were studied. The microspheres were found to be regular in shape and highly porous. The prepared microspheres exhibited prolonged drug release (~8 h) and remained buoyant for >10 h. The mean particle size increased and the drug release rate decreased at higher polymer concentrations. No significant effect of the stirring rate during preparation on drug release was observed. In vitro studies demonstrated diffusion-controlled drug release from the microspheres. Microsphere formulation CS4, containing 200 mg calcium silicate, showed the best floating ability (88% buoyancy) in simulated gastric fluid. The release pattern of glipizide in simulated gastric fluid from all floating microspheres followed the Higuchi matrix model and the Peppas-Korsmeyer model.
漂浮微球已被用于实现药物在胃中的长效均匀释放，以开发每日一次的制剂。通过乳液溶剂扩散技术制备漂浮微球，使用（i）硅酸钙（CS）作为多孔载体；（ii）口服降糖药格列吡嗪；以及（iii）Eudragit（®）S作为聚合物，实现了一种无需与粘膜接触即可增加在胃中停留时间的控释系统。研究了各种制剂和工艺变量对颗粒内外形态、粉体学性质、体外漂浮行为、载药量和体外药物释放的影响。发现微球形状规则且孔隙率高。制备的微球显示出长效药物释放（约8小时），并在超过10小时内保持漂浮。在较高聚合物浓度下，平均粒径增大，药物释放速率降低。未观察到制备过程中的搅拌速率对药物释放有显著影响。体外研究表明药物从微球中以扩散控制方式释放。含有200mg硅酸钙的微球制剂CS4在模拟胃液中显示出最佳的漂浮能力（88%浮力）。所有漂浮微球中格列吡嗪在模拟胃液中的释放模式均符合Higuchi基质模型和Peppas-Korsmeyer模型。
