Structural and Kinetic Characterization of Unexpired and Expired Drugs by Proton Nuclear Magnetic Resonance (1H NMR) Relaxometry and Fourier Transform Infrared (FT-IR) Spectroscopy.

The pollution with expired drugs of aquatic environments, in particular rivers and lakes, has lately become a major worldwide problem. Thus, the interest in the exact quantity of pharmaceutical waste as well as the management after the expiration date is very high. For the present study, expired drugs in the form of tablets, capsules, and powders collected from the Romanian population and unexpired medicines as the same tablets, capsules, and powders purchased from the local pharmacy were analyzed. Advanced 1H-NMR (proton nuclear magnetic resonance) combined with Laplace data analysis and Fourier transform infrared (FT-IR) spectroscopy were used for the characterization of the unexpired and expired drugs. In order to assess the dynamics of dissolution of drugs in aqueous environment, various kinetic measurements of NMR relaxometry, electrical conductivity (EC) and visible near-infrared spectroscopy were performed and their performance in the differentiation of unexpired and expired drugs was evaluated. [ABSTRACT FROM AUTHOR]