Запорожский государственный медицинский университет, Запорожье, Украина Development and Validation of UV Spectrometric Method for Estimation of Aminexil (Kopexil) in Bulk Разработка и валидация УФ-спектрофотометрического метода определения аминексила (копексила) в субстанции ______________________ Abstract __________________________________________________________________________ Background. <...> Lately Aminexil (Kopexil) is widely added in the hair products to thicken the roots, but there is no reported simple, fast and accurate method to determine quantity of Aminexil just by UV-vis spectrometer. <...> Objective: to develop method of Aminexil determination by UV spectroscopy and validate it for linearity, range, accuracy, precision, ruggedness and robustness. <...> The conditions and concentration of Aminexil were optimized according to the linear correlation with maximum UV absorbencies. <...> A simple, precise, accurate, reproducible and low cost UV-spectrophotometric method has been developed and validated for the quantification of Aminexil in bulk. <...> The linearity was found for UV absorption maximum at the 284 nm in the concentration ranges of 1.0–1.8 mg/100mL in 0.1 M HCl solution with r2 =0.9987. <...> Conclusion: The proposed ready-to-use technique can be successfully used for determination of Aminexil in bulk and for future studies in pharmaceutical formulations. <...> Экспериментально были подобраны условия определения и концентрация растворов аминексила в 0,1 М HCl в соответствии с корреляцией между концентрацией и значениями максимальной оптической плотности при 284 нм. <...> Surprisingly, there are still reported only few researches, aimed at new therapies to prevent hair loss and enhance hair growth [3–5]. <...> Among recently used hair enhancers is known Kopexil (trade name Aminexil) – the 4-pyrrolidine-2, 6-diaminopyrimidine-1-oxide or 6-amino2-iminopyrimidin-1(2H)-ol (its tautomeric form), which is an altered form of widely used Minoxidil (Fig. 1) [6, 7]. <...> The search for quantity estimation studies exposes, that there are no simple Aminexil determination just by UV absorption, because it is the most commonly used simple method for laboratories in Ukraine. <...> Among found ones is a report of the simultaneous determination of Minoxidil and Aminexil by RP-HPLC method in 0.1% orthophosphoric acid and methanol solution in the ratio of 60:40 v/v at a flow rate of 1 mL/min6 with mentioned absorbance maximum at the 250 <...>