Introduction. Regulatory documentation is an important tool for ensuring the safety and efficacy of new drugs. Pharmaceutical articles (PM) must contain validated methods for determining authenticity (identification) indicators. The validation procedure allows for the timely identification of shortcomings in the process of developing new methods and their improvement at early stages.

The aim of study is to develop and validate a method for determining a new biologically active compound 5-methyl-N-phenyl-7-(4-fluorophenyl)-4,7-dihydrotetrazolo [1,5-a]pyrimidine-6-carboxamide by spectrophotometry in the UV region. For the validation assessment of the determination method, the following characteristics were selected: specificity, linearity, correctness, precision under repeatability conditions (convergence).

Material and methods. The following samples and solvents were used in the experiment: substance (colorless crystalline powder); DMF solvent; UV-1800 spectrophotometer, manufactured by Shimadzu, Japan.

Results. To assess the specificity, the absorption spectrum of the substance was obtained in the selected range in the UV region. The spectrum shows an absorption maximum at 285 nm. To establish the specific absorption index, sample solutions were prepared in the concentration range from 0.00060% to 0.0010% and it was equal to 270. The linearity of the method was established based on the study of the dependence of optical density on the content at 5 concentration levels from 80 to 120%. The acceptance criterion is the correlation coefficient, it is 0.9954. The validated method is considered correct if the values accepted as true lie within the confidence intervals of the corresponding average analysis results. The determination was carried out at 3 concentration levels (80%, 100%, 120%) by determining the content of the analyzed compound in model solutions. The acceptance criterion is the average percentage of openness and its average value should be within 100±5%, it is within the range from 97.5% to 102.0%. The repeatability of the analytical method was assessed based on six independent results obtained under the same regulated conditions in one laboratory. The calculated value of the variation coefficient is 1.5%, and the relative error of determination is 0.54% with a confidence probability of p=95%, which indicates the precision of the method under repeatability conditions.

Conclusion. The value of the specific absorption index of a new biologically active compound has been established, which can be used to establish authenticity (identification) and determine the quantitative content when developing a pharmacopoeial article. A validation assessment of the developed method has been carried out.