Study of in-vitro release characteristics of carbamazepine extended release semisolid matrix filled capsules based on Gelucires

Various extended release carbamazepine (CBZ) formulations have been developed previously, in order to reduce the frequency of dosing in chronic therapy and to decrease the variability in drug plasma concentration. In the present study, the suitability of different grades of Gelucires (G, glyceride based excipients) to formulate CBZ extended release capsules by the application of semisolid matrix (SSM) filling capsule technology was investigated. The possible modification of CBZ release kinetics by using Gelucire blends or inclusion of hydrophilic additives in the SSM was studied. The effect of ageing on some selected formulations was also evaluated, using scanning electron microscopy and differential thermal analysis. Twenty-one capsule formulations were prepared and assessed for their release characteristics. The mechanism of drug release from the test formulations was studied. The following results were obtained: a) Release data could not be correlated to the melting point (mp) of Gelucires used, pointing to relative lipophilicity of the base as a more important determinant of drug release. Among Gelucire grades having melting points higher than 37°C, the release rate proved to be highly dependent on the HLB value and matrix composition. b) CBZ release occurred by different mechanisms, including matrix disintegration, diffusion and or erosion depending on the vehicle employed. c) Zero order release profiles of CBZ were obtained from SSM-based on G50/13, G53/10 and their blends in ratios higher than 1:1 and G53/10 containing croscarmellose sodium. d) The ageing study revealed that these latter formulations, except those based on G50/13, also showed high dissolution stability during one year of shelf ageing. e) PVP, as a polymorphic transformation inhibitor, can be used to reduce the storage-induced changes of some grades of Gelucires. From the above data, it can be concluded that different grades of Gelucires and their blends as well as hydrophilic additives could be successfully used to formulate CBZ extended release SSM filled capsules with various release kinetics.     

正电胶—聚合物钻井液的室内研究与现场应用

本文介绍了正电胶-聚合物钻井液的配方组成、室内性能测试结果和现场应用实例。正电胶与聚合物复配使用时有很好的互补性，得到的钻井液抑制能力强，失水造壁性好，动塑比高，卡森极限粘度低，能显著提高泥页岩稳定性，清洁井眼，提高机械钻速，应用于定向井取得了成功。这是一种实用价值很高的钻井液。     

Lumped- Differential Formulations for Drying in Capillary Porous Media

Simultaneous heat and mass transfer, during drying of moist capillary porous media, is modeled through different lumped-differential formulations, obtained from spatial integration of the original set of Luikov's equations for temperature and moisture potential. Besides the classical lumped system analysis, improved formulations are proposed, of same mathematicai simplicity, based on approximate evaluations of both temperature and moisture gradients within the medium. The relative merits of such improved zero-dimensional formulations are established, through critical comparisons against analytical solutions for the full partial diflerential system, over a wide range of the governing parameters.     

天然混合羧酸（盐）复合驱油体系的研究

研究了天然混合羧酸（盐）复合驱油溶液与大庆、胜利原油构成的体系的界面性质，考察了Ｎａ２Ｃｏ３、ＮａＨＣＯ３、ＮａＣｌ、ＨＰＡＭ、助表面活性剂对体系界面性质的影响，提出了复合驱油体系的配方。研究结果表明，天然混合羧酸（盐）可使复合驱油溶液与大庆或胜利原油之间的界面张力降至超低值。     

提高FH-7复合杀菌剂抗冻性研究

ＦＨ－７是１２２７与另外两种主要组分的复配物水溶液，抗冻性能较好，但在冬季当气温过低时仍会结冰而不能正常使用。加入乙二醇、乙醇、无机盐等抗冻剂未能得到抗冻性能合乎要求的杀菌剂，加入少量的一种新的杀菌组分并调整原配方组分比例，得到了抗冻性能良好，杀菌性能优于原配方，生产成本较低或接近原配方的系列杀菌剂ＦＨ－７Ａ－ＨＦ－７Ｅ。     

甲基戊炔醇的合成及缓蚀性能

本文介绍了甲基戊炔醇的合成及缓蚀性能研究结果。甲基戊炔醇的产率达９２％，用正交设计试验法进行配方，以８０℃的１５％盐酸为腐蚀介质，Ｎ８０钢片为腐蚀试件，得到了合理的甲基戊炔醇缓蚀剂配方。以甲基戊炔醇配制的缓蚀剂，其性能优于以两种基他炔醇配制的缓蚀剂。