hyphenated techniques

The impurities in pharmaceuticals are unwanted chemicals that remain with the active   pharmaceutical ingredients (APIs). Impurities plays a major role in pharmaceuticals therefore profiling of impurity is very important. The pharmaceutical impurities are the unwanted chemicals that remain or are generated during the manufacturing process. These impurities are classified into three main categories such as organic, inorganic and residual solvents. Organic impurities include intermediate, starting material, degradation products, reagents, ligands, catalyst and by products. Whereas inorganic impurities are heavy metals, residual solvent, inorganic salt, filter, aids, charcoal and reagents. Impurity profiling helps in detection, identification and quantification of various types of impurities. It is a best way to characterize quality and stability of bulk drugs and pharmaceutical formulations. Due to rapid development of the analytical methodology it is imperative to review problems related to impurities present in the drug substances and drug products with their solutions. Various regulatory authorities like ICH, USFDA TGA, WHO, ANVISA, Canadian Drug and Health Agency are emphasizing on drug substance and drug product purity requirements and on identification of impurities in active pharmaceutical ingredients as presence of impurities even in small amounts may influence the efficacy and safety of the pharmaceutical products. Thus enlightening the need of impurity profiling of drug substances in pharmaceutical research this review focuses on various classification for identification as well as quantification of impurities present in the pharmaceuticals. The analytical techniques used for impurity profiling of drugs are LC-MS-MS, LC-NMR, LC NMR- MS, GC-MS, and LC-MS, DSC, TGA, ICP-MS, IC, HPLC and GC.

To assure the quality of drugs, impurities must be monitored carefully. It is important to understand what constitutes an impurity and to identify potential sources of such impurities. Selective analytical methods need to be developed to monitor them. It is generally desirable to profile impurities to provide a yardstick for comparative purposes. New impurities may be observed as changes are made in the synthesis, formulation, or production procedures, albeit for improving them. At times it is necessary to isolate and characterize an impurity when hyphenated methods do not yield the structure or when confirmation is necessary with an authentic material. Availability of an authentic material can also allow toxicological studies and provide a standard for routine monitoring of the drug product.