Quantitative determination of sildenafil (Viagra) and its metabolite (UK-103,320) in fluid and tissue specimens obtained from six aviation fatalities.

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-d(8) as an internal standard for more accurate and reliable quantitation. The quantitation of sildenafil and UK-103,320 in postmortem fluid and tissue specimens obtained from victims from six separate aviation fatalities is described. The method incorporates solid-phase extraction and liquid chromatography-tandem mass spectrometry (LC-MS-MS) and MS-MS-MS utilizing an atmospheric pressure chemical ionization ion trap MS in the positive chemical ionization mode. Solid-phase extraction provided an efficient sample extraction yielding recoveries ranging from 79 to 88%. The limits of detection for sildenafil and UK-103,320 were 0.39 and 0.19 ng/mL, respectively. The linear dynamic range for both compounds was 0.78-800 ng/mL. 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.