Melia C D, Hansraj B R, Khan K A, Wilding I R
Department of Pharmaceutical Sciences, School of Pharmacy, University of Nottingham, UK.
Pharm Res. 1991 Jul;8(7):899-902. doi: 10.1023/a:1015859713992.
A colorimetric ion-pair complexation method has been developed which provides a simple and rapid way of quantifying Eudragit RS100 and RL100 in pharmaceutical dosage forms. The quaternary ammonium groupings in these polymers appear to form an ion-pair complex with the dye tropaeolin OOO. When extracted into an organic phase, the optical density at 484 nm is linearly related to polymer concentration. Control of pH is important, and it should be maintained within the range 4.5 to 9.0. A wide range of pharmaceutical excipients commonly used in tablet, pellet, and film-coating formulations did not interfere with formation of the complex, but certain drugs were found to significantly enhance or decrease the assay response. Good reproducibility, precision, and accuracy were demonstrated when the method was applied to a film-coated pellet formulation containing an interfering drug (promethazine hydrochloride). However, removal of interfering substances must be optimized. The method was sufficiently sensitive for the determination of polymer on a single dose unit of encapsulated beads.
已开发出一种比色离子对络合方法，该方法为定量药物剂型中的Eudragit RS100和RL100提供了一种简单快速的方式。这些聚合物中的季铵基团似乎与染料金莲橙OOO形成离子对络合物。当萃取到有机相中时，484 nm处的光密度与聚合物浓度呈线性关系。pH的控制很重要，应保持在4.5至9.0范围内。片剂、微丸和薄膜包衣制剂中常用的多种药用辅料不会干扰络合物的形成，但发现某些药物会显著增强或降低测定响应。当该方法应用于含有干扰药物（盐酸异丙嗪）的薄膜包衣微丸制剂时，显示出良好的重现性、精密度和准确度。然而，必须优化干扰物质的去除。该方法对测定包衣微丸单剂量单位中的聚合物具有足够的灵敏度。
