Identification of Sildenafil (Viagra) and Its Metabolite (UK 103,320) in Six Aviation Fatalities

Abstract : During the investigation of aviation accidents, postmortem samples from victims are submitted to the Federal Aviation Administration's Civil Aerospace Medical Institute for toxicological analysis. This report presents a rapid and reliable method for the identification and quantitation of sildenafil (Viagra ) and its active metabolite, UK-103,320. This procedure utilizes sildenafil-d8 as an internal standard for more accurate and reliable quantitation. The method incorporates solid-phase extraction and LC/MS/MS and MS/MS/MS utilizing an atmospheric pressure chemical ionization ion trap mass spectrometer in the positive chemical ionization mode. Solid-phase extraction provided an efficient sample extraction yielding recoveries ranging from 79 - 88%. The limit of detection for sildenafil and UK-103,320 was 0.39 and 0.19 ng/mL, respectively. The linear dynamic range for both compounds was 0.78 - 800 ng/mL. The method was employed for the determination of sildenafil and UK-103,320 in postmortem fluid and tissue specimens collected from 6 fatal aviation accident victims. The current method proved to be simple, accurate, and robust for the identification and quantitation of sildenafil and UK-103,320 in postmortem fluids and tissues.