Because of the mutagenic and carcinogenic effects of impurities, controlling and monitoring them has become a very important process in drug development and production. This process, also called quality control, formed the basis of the pharmaceutical industry. FTIR and Raman spectroscopy have a wide range of applications, from the characterization of drug formulations to the explanation of kinetic processes and the determination of adulteration on many foods and food products with different properties. An ability to analyze with low cost and reliable results shows a great promise for using these methods in drug quality control. It is seen that choosing multivariate methods to be applied in the evaluation of FTIR and Raman spectra quickly and accurately in terms of quality and safety of foods increases the performance of identification. In this chapter, impurities in pharmacology are defined, and applications on the quality of drugs and adulteration of foods using FTIR and Raman spectroscopy are explained.
Top1. Impurity In Pharmacology
Pharmacology is a branch of science that examines the structure and effects of drugs, as well as the mechanisms of these effects on living organisms (Hacker, 2009; Berger et al., 2011; Magoma, 2013). Impurity, which is one of the most important concepts in pharmacology, appears in the process of drug raw material synthesis and preparation of drug dosage forms. Impurity is defined by the Guidelines of the International Conference on Harmonization (ICH) as “any component of a drug active ingredient that is not a chemical entity”, on the other hand, it is also defined as the unwanted chemicals that remain with the active pharmaceutical ingredients (API) or that are not included in the drug formulation that are formed during the synthesis of new drugs (Basak et al., 2007; Hussain et al., 2018). Therefore, any foreign material present in the drug substance is considered an impurity even if it is completely inert or has superior pharmacological properties. In this case, the importance of impurities in drugs increases in the quality control process.
There are various reasons for the formation of impurities in drugs. The most common of these reasons are starting materials in API synthesis, byproducts, residues in solvents, decomposers formed during long-term storage, contaminants from packaging components produced in the same facility and other pharmaceutical products, heat on the drug product, the influence of light and oxidants, metal impurities in trace rate, changes in the pH of the formulation (Prabu and Suriyaprakash, 2010; Parajuli et al., 2018). Therefore identification of active pharmaceutical ingredients and impurities in drugs, quantification and control have an important role in drug development and quality control. Impurities in drugs are classified into three main categories: organic impurity, inorganic impurity and residual solvent (Prabu and Suriyaprakash, 2010; Jain and Sharma, 2017; Qiu and Norwood, 2007; Pilaniya et al., 2010).
Organic Impurity
Organic impurity is the type of impurity that may occur during the production process and/or storage of the drug substance (Ayre et al., 2011). This impurity can be caused by starting materials, intermediates, by-products, degradation products, reagents, ligands, catalysts, specified or unspecified, volatile or non-volatile chemicals used in chemical synthesis (Hussain et al., 2018; Ayre et al., 2011).
Inorganic Impurity
Inorganic impurity often occurs during the bulk production of drugs. While pharmaceutical raw materials such as acids, alkalis, alkaline earth compounds, inorganic salts used during synthesis form the basis of inorganic impurities, it has been seen in the literature review that it causes metal residue and heavy metal impurity in water and metal catalysts used during drug production (Roj, 2002).
Solvent Based Impurity
Solvent-based impurities are the impurities that pass from the solvent to the drug structure during processes such as crystallization, precipitation, extraction, separation, chromatographic purification, which are formed by using organic or inorganic liquids during drug synthesis. These solvents do not have any therapeutic benefit and in some cases they must be removed from the drug substance as they are toxic (Ahuja, 2007; Roj, 2002).
When drug impurities are evaluated, it is seen that they originate from starting materials, production stage, drug perishability and production-storage.
2. Quality Control In Pharmacology
Product quality is of vital importance in the pharmaceutical industry. The ability to systematically produce products of the desired quality is an indispensable element of this industry (Mike et al., 2013). Product quality is of vital importance in the pharmaceutical industry by reason of producing high quality and economical products, gaining competitive advantage and protecting customer rights and health. In order to maximize the desired effect of the drug and minimize its side effects in pharmacological production, quality control tests should be carried out at every stage (Turan, 1982).
Separation and identification of structurally similar substances with different physicochemical properties such as API and impurities form the basis of pharmaceutical quality control (QC) (Galea et al., 2017). Impurity researches are done incrementally during drug development to ensure drug safety and to obtain appropriate information needed when the patient is exposed to impurities.