DETERMINATION OF THE ACTIVE INGREDIENT (5-ETHYL-2'-DEOXYURIDINE) OF THE OINTMENT 'REVIDUR' BY UV AND NIR SPECTROSCOPY

Abstract

UV spectrophotometric and NIR spectroscopic methods were developed for determining the active ingredient (5-ethyl-2'-deoxy-uridine) in the antiviral ointment (Revidur). UV spectrophotometric measurements were carried out at 263 nm with solution of the ointment in absolute ethanol prepared by ultrasonication. Calibration solutions contained the matrix. The standard error of the method was 0.016%, the correlation coefficient of the calibration curve was 0.999 in the range 0.25 to 2.5% drug content. Two NIR methods are described in the present work. In one of the methods, NIR reflectance spectra were taken of solutions and concentration determinations were carried out based on the second derivative of the spectra at 1166 nm. The correlation coefficient was equal to that calculated for the UV method, and the standard calibration error was slightly higher, 0.05%. The advantage of the method is its quickness if calibration data are available. The simpler method developed seems to be suitable for the determination of the drug directly in the ointment without any pretreatment. In the is method, the second derivative of the NIR reflectance spectra measured at 2466 and 1528 nm are used. How- ever, due to inhomogeneity problems with the calibration samples resulting in a standard calibration error one order of magnitude higher than that for the solution technique, we consider our results with the direct method to by only preliminary onesand intend to continue our studies.