A METHODOLOGICAL APPROACH TO DESIGNING EXPERIMENTS WHEN DEALING WITH IDENTIFICATION TESTS FOR MEDICINAL PRODUCT COMPONENTS (AS ILLUSTRATED BY ASCORBIC ACID)

Abstract

The need for identification testing of active substances or excipients in multi-component medicinal products, including the use of qualitative tests, calls for research substantiating the choice of tests and test conditions with due regard to interference effects caused by other components of medicinal products and the amount of the sample used. The aim of the study was to develop a methodological approach to designing experiments while selecting qualitative reactions for identification testing of a medicinal product component based on the results of studies investigating the possibility of using known qualitative tests (as illustrated by ascorbic acid in a multi-component product — 0.4 mg of ascorbic acid per 100 mg of the vial contents) with due regard to interference on the part of other medicinal product components and the amount of the sample used. Material and methods: the study focused on a multi-component medicinal product — lyophilisate for solution for intravenous and intramuscular injections containing an antiinflammatory active substance and ascorbic acid as a stabilizing agent (antioxidant). The analysis of literature sources helped to determine qualitative tests that were assessed for potential use for identification testing of ascorbic acid as a component of the analysed medicinal product. The study involved experimental testing of the qualitative reactions based on acidic and reducing properties of ascorbic acid. Results: it was demonstrated that several well-known qualitative tests could be used for identification testing of ascorbic acid as a component of the analysed medicinal product, namely, the reaction of ferrous ascorbate formation and the reaction of silver nitrate reduction to metallic silver after preliminary separation of ascorbic acid from the other medicinal product components, as well as the reaction of Prussian blue formation, iodine test and reaction with a potassium permanganate solution, which do not require additional sample preparation. It is not practicable to use the reaction with a methylene blue solution and the Fehling’s reagent reaction for this particular medicinal product, since their results are feeble. Conclusions: the analysis of the multi-component medicinal product helped to develop a methodological approach to choosing qualitative reactions for identification testing of one of the medicinal product’s components (e.g., ascorbic acid). The suggested algorithm includes the choice of reactions, determination of their sensitivity and applicability for a particular medicinal product, analysis of the other components’ effects on the results of the chemical reaction, and the need for additional sample preparation. The whole complex of the studies performed helped to determine qualitative reactions and optimal conditions for identification testing of the analysed substance.

Keywords

• methodological approach
• qualitative reactions
• test conditions
• ascorbic acid
• antioxidant
• parenterals