Determination of pKa(s) of nilutamide through UV-visible spectroscopy

Abstract The knowledge of a drug's physicochemical properties, namely the ionization constants, are of extreme importance in the development of new drug delivery approaches, including the ones based on nanostructures. For the first time, it was experimentally determined the pK a values of the antiandrogen nilutamide, an important drug clinically used to prevent tumor development. The approach exploited UV–Visible spectrophotometry, a method recognized to furnish pK a values with accuracy and reproducibility. In the pharmaceutical research area, the ionization constant (pK a ) is a physicochemical parameter very important since it influences the dissolution capacity of active ingredients and the route for pharmaceutical administration (formulation design of the drug molecules). Two different methods for pK a determination of nilutamide based on the UV–Visible spectra were applied, and the associated standard deviations were calculated. This work revealed two pK a values for nilutamide, approximately, 10.0 and 14.0. Additionally, a validation of the obtained results was performed by repeating the determinations through a different laboratory operator.