Phosphodiesterase (PDE5) inhibition assay for rapid detection of erectile dysfunction drugs and analogs in sexual enhancement products

• Published in: Drug testing and analysis 2018-08, Vol.10 (8), p.1315-1322
• Main Authors: Santillo, Michael F., Mapa, Mapa S.T.
• Format: Article
• Language: English
• Subjects: Adulteration; dietary supplement; Dietary supplements; Drug testing; enzyme sensor; Erectile dysfunction; PDE5; phosphodiesterase
• ISSN: 1942-7603; 1942-7611
• DOI: 10.1002/dta.2375

Products marketed as dietary supplements for sexual enhancement are frequently adulterated with phosphodiesterase‐5 (PDE5) inhibitors, which are erectile dysfunction drugs or their analogs that can cause adverse health effects. Due to widespread adulteration, a rapid screening assay was developed to detect PDE5 inhibitors in adulterated products. The assay employs fluorescence detection and is based on measuring inhibition of PDE5 activity, the pharmacological mechanism shared among the adulterants. Initially, the assay reaction scheme was established and characterized, followed by analysis of 9 representative PDE5 inhibitors (IC50, 0.4–4.0 ng mL–1), demonstrating sensitive detection in matrix‐free solutions. Next, dietary supplements serving as matrix blanks (n = 25) were analyzed to determine matrix interference and establish a threshold value; there were no false positives. Finally, matrix blanks were spiked with 9 individual PDE5 inhibitors, along with several mixtures. All 9 adulterants were successfully detected (≤ 5 % false negative rate; n = 20) at a concentration of 1.00 mg g–1, which is over 5 times lower than concentrations commonly encountered in adulterated products. A major distinction of the PDE5 inhibition assay is the ability to detect adulterants without prior knowledge of their chemical structures, demonstrating a broad‐based detection capability that can address a continuously evolving threat of new adulterants. The PDE5 inhibition assay can analyze over 40 samples simultaneously within 15 minutes and involves a single incubation step and simple data analysis, all of which are advantageous for combating the widespread adulteration of sex‐enhancement products. A screening assay was developed to detect erectile dysfunction drugs and analogs in adulterated sex enhancement products. The method is based upon measuring inhibition of phosphodiesterase‐5 (PDE5) activity, the pharmacological mechanism shared among the adulterants. The method can analyze over 40 samples simultaneously within 15 minutes, and detect adulterants at a level of 1.00 mg/g. A distinction of this method is the ability to detect adulterants without prior knowledge of their chemical structures, demonstrating a broad‐based detection capability.