Differential scanning calorimetry as an analytical tool in the study of drug-cyclodextrin interactions

The interactions of trimethoprim, sulphadiazine and sulphamethoxazole with natural (a- b-, g- ) and amorphous (RAMEB) or crystalline (DIMEB) methylated b-cyclodextrins were investigated both in aqueous solution (using phase-solubility analysis) and in the solid state (using DSC supported by X-ray analysis). In particular, DSC studies enabled determination of the relative degree of crystallinity of each drug in its physical and ground mixtures with the different cyclodextrins on the basis of the variation of its heat of fusion in comparison with that of the pure drug. In all cases, the host cavity size was a prevalent factor for the inclusion complexation in liquid state. On the contrary, it had a negligible effect on solid-state interactions in terms of drug amorphization. DIMEB and RAMEB exhibited similar performances in aqueous solution, showing that the presence of methyl-groups improved the complexing and solubilizing properties of b-cyclodextrin. However, DSC studies revealed that RAMEB was clearly more active in performing solid-state interactions, i.e. drug amorphization, and as stabilizing agent for the amorphous state brought forth. This revised version was published online in July 2006 with corrections to the Cover Date.     

A Raman Spectroscopic Investigation of Sulphadiazine and of Its Dirhodium Tetracarboxylate Adducts

A tentative assignment of the vibrational modes of sulphadiazine is made, based on the infrared and Raman data. In addition, dirhodium tetracarboxylates and their adducts with sulphadiazine are investigated by Raman spectroscopy, with emphasis in the identify the metal-metal and metalligand stretching modes.     

High Performance Liquid Chromatographic Determination of Trimethoprim and Sulphadiazine in Medicated Fish Feedstock

Abstract

A high performance liquid chromatographic (HPLC) method for the determination of sulphadiazine and trimethoprim in medicated fish feedstock is described. It is based on the extraction of the drugs into methanol followed by separation on a μ-Bondapak column using an aqueous acetonitrile mobile phase of pH 3.0. The method was validated by determining intra- and inter-assay precision and the coefficient of variation was found to be less than 8% for both drugs. Callbration curves were linear over the range 160–4000 pg drug per g of feedstock and the method was applied to the determination of a commercial feedstock formulation.     

薄层扫描法测定增效联磺片中磺胺嘧啶的含量

本文采用岛津ＣＳ－９３０型薄层扫描仪，以紫外反射吸收方式灵敏快速地测定了增效联磺片中磺胺嘧啶的含量。λｓ＝２７０ｎｍ，散射参数Ｓｘ＝３，薄层厚度０．３ｍｍ；展开剂为氯仿：乙醇：庚烷（１：１：１），平均回收率为９８．０１％，检出限为０．０５μｇ。