PhD, University of Cincinnati, 2017, Arts and Sciences: Chemistry

A considerable number of dietary supplements suspected of containing phosphodiesterase-5 (PDE-5) inhibitors and substituted phenethylamines have been analyzed by the U.S. Food and Drug Administration. Often these samples are found to contain the active pharmaceutical ingredients (API) such as sildenafil or phentermine, and in many cases, products contain multiple PDE-5 inhibitors or substituted phenethylamines. In an analytical setting, it is important to confirm the presence of any API with two or more independent methods, and this requirement can often put undo strain on a laboratory. The development and use of methods that inherently contain two unique identification techniques is preferred, and the creation and validation of three of those methods is outlined here. First, direct deposit Fourier transform infrared detection and mass spectrometric detection (GC/FT-IR/MS) is used to identify PDE-5 inhibitors. Generally, GC/MS is not generally used for this category of drugs due to low volatility; PDE-5 inhibitors often co-elute and can produce non-specific electron ionization fragmentation patterns. In contrast, FT-IR has been proven to be more selective for identifying PDE-5 inhibitors, but is generally not as sensitive as spectrometric techniques. However, it has been shown that each technique can compensate for the other, which allows a wider range of usability. Using this combined technique can save time and resources while still delivering a high level of certainty in identification by providing results from two scientifically uncorrelated techniques. Multiple reference standards were utilized for method validation, including determination of linearity, dynamic range, and limit of detection. Second, a single HPLC-UV method has been developed for the determination of PDE-5 inhibitors and related analogs in pharmaceutical dosage forms and dietary supplement products. Using this protocol, 14 PDE-5 inhibitor compounds can be separated and determined in a single an (open full item for complete abstract)

Committee: Peng Zhang Ph.D. (Committee Chair); Anna Gudmundsdottir Ph.D. (Committee Member); Laura Sagle Ph.D. (Committee Member) Subjects: Chemistry