Aildenafil has been found as an adulterant in a variety of supplements which are sold as "natural" or "herbal" sexual enhancement products. The United States Food and Drug Administration has warned consumers that any sexual enhancement product that claims to work as well as prescription products is likely to contain such a contaminant.
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^Liu, Baoshun. Preparation of pyrazolopyrimidine derivatives for treatment of impotence. WO 2003016313
^Gryniewicz, CM; Reepmeyer, JC; Kauffman, JF; Buhse, LF (2009). "Detection of undeclared erectile dysfunction drugs and analogues in dietary supplements by ion mobility spectrometry". Journal of pharmaceutical and biomedical analysis49 (3): 601–6. doi:10.1016/j.jpba.2008.12.002. PMID19150190.
^Choi, Dong Mi; Park, Sangaeh; Yoon, Tae Hyung; Jeong, Hye Kyoung; Pyo, Jae Sung; Park, Janghyun; Kim, Deukjoon; Kwon, Sung Won (2008). "Determination of analogs of sildenafil and vardenafil in foods by column liquid chromatography with a photodiode array detector, mass spectrometry, and nuclear magnetic resonance spectrometry". Journal of AOAC International91 (3): 580–588. PMID18567304.
^Reepmeyer, John C.; Woodruff, Jeffrey T. (2007). "Use of liquid chromatography-mass spectrometry and a chemical cleavage reaction for the structure elucidation of a new sildenafil analogue detected as an adulterant in an herbal dietary supplement". Journal of Pharmaceutical and Biomedical Analysis44 (4): 887–893. doi:10.1016/j.jpba.2007.04.011. PMID17532168.
^Reepmeyer, John C.; Woodruff, Jeffrey T.; 'Avignon, D. Andre. (2007). "Structure elucidation of a novel analogue of sildenafil detected as an adulterant in an herbal dietary supplement". Journal of Pharmaceutical and Biomedical Analysis43 (5): 1615–1621. doi:10.1016/j.jpba.2006.11.037. PMID17207601.