Murthy K S, Samyn J C
J Pharm Sci. 1977 Sep;66(9):1215-9. doi: 10.1002/jps.2600660903.
The influence of shear mixing on the in vitro dissolution properties of several experimental capsule formulations containing lubricants was investigated. The studies were carried out in 2.8-liter laboratory V-blender equipped with a high-speed intensifier bar, using nitrofurantoin and procainamide hydrochloride as active drugs, powdered lactose and starch as excipients, and magnesium stearate and magnesium lauryl sulfate as lubricants. These studies revealed a pronounced inhibitory effect on drug dissolution due to shear in powder mixtures containing magnesium stearate; even at the maximum lubricant level of only 2%, high mixing markedly altered the in vitro dissolution rate. In systems with magnesium lauryl sulfate, the shear effect was less pronounced (nitrofurantoin blends) or absent (procainamide hydrochloride blends). The poor dissolution characteristics noted with magnesium stearate--shear combinations seem to result from the formation of a hydrophobic film around the powder mass, preventing wetting and deaggregation.
研究了剪切混合对几种含有润滑剂的实验性胶囊制剂体外溶出特性的影响。实验在配备高速强化棒的2.8升实验室V型混合器中进行，使用呋喃妥因和盐酸普鲁卡因胺作为活性药物，乳糖粉和淀粉作为辅料，硬脂酸镁和月桂醇硫酸镁作为润滑剂。这些研究表明，在含有硬脂酸镁的粉末混合物中，剪切力对药物溶出有显著的抑制作用；即使在仅2%的最大润滑剂水平下，高强度混合也会显著改变体外溶出速率。在含有月桂醇硫酸镁的体系中，剪切作用不太明显（呋喃妥因混合物）或不存在（盐酸普鲁卡因胺混合物）。硬脂酸镁与剪切力组合所呈现的较差溶出特性似乎是由于在粉末团块周围形成了疏水膜，从而阻止了润湿和解聚。
