РАЗРАБОТКА МЕТОДИКИ ОПРЕДЕЛЕНИЯ ВОДЫ МЕТОДОМ КУЛОНОМЕТРИЧЕСКОГО ТИТРОВАНИЯ ПО ФИШЕРУ В ФАРМАЦЕВТИЧЕСКИХ СУБСТАНЦИЯХ ГРУППЫ ФТОРХИНОЛОНОВ

Abstract

Abstract. A wide spectrum of antibacterial action of fluoroquinolones of the III generation (levofloxacin) and IV generation (moxifloxacin) determines their active use for the treatment of various infectious diseases. The quality of the pharmaceutical substances included in their composition affects the manifestation of the therapeutic effect of drugs. Decomposition of the active substance and the formation of undesirable impurities can occur if storage conditions are violated (high humidity, temperature, light). All these factors can significantly affect the pharmacological activity, up to the manifestation of a toxic effect. The humidity regime is especially important for hygroscopic substances (moxifloxacin) and substances containing water of crystallization in the chemical structure (levofloxacin). Weathering of crystallization water is possible at low humidity; this may affect the weight of the sample of the medicinal substance, which is important in the technological process in the manufacture of dosage forms. As a result, it may affect the quality of the finished product. Therefore, the determination of the water content during the quality control of pharmaceutical substances is mandatory. Coulometric titration at a constant current strength (galvanostatic coulometry) is a promising method for determining water in substances. Titration is carried out with electrogenerated iodine, which is formed during the anodic oxidation of iodide ions contained in the background electrolyte. Further, iodine, oxidizing sulfur (IV) in a sulfur-containing compound in the presence of water according to the Fischer reaction, is reduced to iodide ions, from which iodine can be generated again. The cyclic nature of the process makes it possible to carry out multiple measurements without changing the background electrolyte. The water content is calculated from the amount of electricity used for titration. The advantages of this method are specificity, no need for preliminary standardization of the titrant, rapidity and simplicity of the experiment. A unified method for the determination of water by coulometric Fischer titration in levofloxacin and moxifloxacin substances has been developed. The validation evaluation of the method for determining water in the substance of levofloxacin showed its validity in terms of specificity, linearity (r=0.9977), correctness and precision (RSD 2%). The methods can be used in the practice of control and analytical laboratories to assess the "Water" parameter in these pharmaceutical substances.