High Sensitive Detection and Quantification of Thirty-Two Synthetic PDE-5 Inhibitors and Analogues Adulterated in Health Supplements Using LC/MS/MS

In recent years, synthetic phosphodiesterase type 5 enzyme (PDE-5) inhibitors like sildenafil (active component of VIAGRA) were found as adulterant in some health supplements described as plant or herbal products. Only seven synthetic PDE-5 inhibitors, namely, sildenafil, tadalafil, vardenafil, avanafil, udenafil, mirodenafil and lodenafil carbonate are approved officially to be used for the treatment of erectile dysfunction (ED) in men. The adulteration is illegal and may be also dangerous for consumers, because not only the above PDE-5 inhibitors, many newly appeared analogues that are synthesized with minor modification of the parent structures are also found used as adulterants. Analytical techniques like HPLC and LC/MS/MS have been applied for screening and quantitation of PDE-5 inhibitors and their analogues. We describe here a high sensitivity LC/MS/MS method for detection and quantification of thirtytwo synthetic PDE-5 inhibitors and analogues spiked in health products.