b第二章杂质检查.ppt

第二章 杂质检查Chapter 2 Limit Test 药物的纯度是指药物纯净的程度。它是判定药品质量优劣的一个重要指标。 The level of purity which can be attained in the manufacture of pharmaceutical products depends partly on the cost-effectiveness of the process and the purification methods available and partly on the stability of the product. Section 2. The sources of impurities 1. The manufacturing process The majority of modern pharmaceutical chemicals are prepared by organic synthesis from starting materials which are, themselves, either synthetic organic chemicals or natural products isolated from biological sources. The process itself may, therefore, introduce impurities into the final products. The starting material and its impurities Intermediates Reagents, solvents and catalysts used in the process Reaction vessels Pharmaceutical chemicals may be either isolated from biological sources or prepared by synthesis from chemical starting materials. Biological sources include plant, animal tissues and microbiological fermentation.Whatever the process, the identity of the source material should be verified and its quality established. Additionally, the presence of any related or non-related substance present in the starting material which might be carried through the process to contaminate the final product should be identified. 3. Chemical and physical instability Impurity can arise during storage as a result of chemical instability. A number of pharmaceutically important substances are known to undergo chemical decomposition when stored under non-ideal conditions。The nature of the decomposition, which is often catalysed by light, traces of acid or alkali, air oxidation, water vapour, carbon dioxide and traces of metallic ions, can frequently be predicted from a knowledge of the chemical properties of the substance. 3. Classification Resource: general impurities and specific impurities 一般杂质，如酸、碱、