Hair Analysis to Demonstrate Administration of Sildenafil to a Woman in a Case of Drug-Facilitated Sexual Assault

Abstract

The drug sildenafil (Viagra, Pfizer) and, more recently, tadalafil (Cialis, Lilly-Icos) and vardenafil (Levitra, Bayer), has drawn public attention to aphrodisiacs. The search for such substances dates back millennia. Adverse effects associated with these drugs include hypotension, tachycardia, headache, flushing, blurred vision, dyspepsia, and musculoskeletal pain. Although sildenafil has been marketed for erection of the penis, recent attention has been paid to its application for women, including enhancement of success of in vitro fertilization but also better sexual responses (increased desire, satisfaction, and orgasm) in cases of sexual disorders. Today, there is a debate on internet forums about the potential properties of sildenafil to enhance women's sexual pleasure. This laboratory was asked to analyze a 12-cm length of light brown hair submitted by a British police force following an allegation that a young female had been subjected to sexual assaults over a two-year period. The female was 15-17 years of age at the time. The alleged perpetrator was her stepfather, and there was some suspicion that drugs may have been administered to facilitate the attacks. After decontamination and segmentation (6 x 2-cm section), the specimen was analyzed by liquid chromatography coupled with tandem mass spectrometry after alkaline (pH 9.5) extraction using dichloromethane/ isopropanol/n-heptane (25:10:65, v/v/v). The limit of quantitation was 5 pg/mg. The proximal segment tested positive for sildenafil at 38 pg/mg, and all others proved negative. This was in accord with the victim's claim. In the absence of any controlled studies, it was impossible to put any quantitative interpretation on the measured concentration.