Anti-Norfentanyl polyclonal antibody

Fentanyl is a potent synthetic narcotic analgesic administered in the form of a transdermal patch for the management of chronic pain. A 78-year-old woman with a history of cancer was found dead in bed. She was lying on her back. The external examination revealed 10 Durogesic (R) transdermal therapeutic systems (100 mu g/h fentanyl) on the body. Liquid-liquid extraction and liquid chromatography tandem mass spectrometry with electrospray source in positive ionization mode was applied for the quantitation of fentanyl and its major metabolite norfentanyl in the post-mortem samples. Fentanyl-d5 and norfentanyl-d5 were used as internal standards. Multiple reaction monitoring was used for specific detection. Calibration was performed by addition of standard solutions to drug-free matrix (blood, urine and liver) prior to extraction. The method showed good linearity for fentanyl and norfentanyl over a concentration range of 5-150 mu g/L in reconstituted extracts with coefficients of determination equal or greater than 0.998. Percent mean within-day precision and accuracy of 0.9-1.0% and 99.4-101.1% for fentanyl and 2.0-4.5% and 93.1-101.0% for norfentanyl were obtained. Mean extraction recoveries varied between 95.5% and 100.3% for fentanyl and 39.2-57.4% for norfentanyl. The following fentanyl (norfentanyl) concentration in the post-mortem samples were measured; 28.6 mu g/L (3.0 mu g/L) in right and 28.2 mu g/L (3.5 mu g/L) in left subelavian blood, 21.3 mu g/L (< 2 mu g/L) in right and 20.9 mu g/L (< 2 mu g/L) in left femoral blood, 37.6 mu g/L (4.2 mu g/L) in right and 33.9 mu g/L (4.4 mu g/L) in left ventricular blood, 282.9 mu g/L (121.2 mu g/L) in urine, 688.2 mu g/L in stomach contents, 122.5 mu g/L (25.4 mu g/L) in bile, 19.5 mu g/L (< 2 mu g/L) in vitreous humour, 203.0 mu g/kg (26.6 mu g/kg) in liver and 78.6 mu g/kg (46.3 mu g/kg) in kidney. We concluded that the woman's death was caused by acute intoxication with fentanyl. The manner of death was presumed to be suicide due to excessive administered Durogesic (R) transdermal therapeutic systems. (c) 2006 Elsevier Ireland Ltd. All rights reserved.

Norfentanyl has been identified previously as a urinary metabolite of fentanyl. However, at clinically relevant concentrations, norfentanyl concentrations are below the limits of detection. The use of labeled drug in metabolic studies is a standard approach to overcome the limitations imposed by metabolite concentrations that are below detection limits. Unfortunately, the available tritium-labeled fentanyl yields unlabeled norfentanyl following N-dealkylation. Thus, we have developed a technique to monitor the N-dealkylation of fentanyl using the other products of N-dealkylation. The biotransformation of fentanyl was studied in human liver microsomes. After incubation with human liver microsomes for 20 min, almost 50% of a 0.03 mu M concentration of [H-3]fentanyl was metabolized to the [H-3]N-dealkylated metabolite phenylacetaldehyde, which was then converted principally to [H-3]2-phenylethanol and to a smaller extent to [H-3]phenylacetic acid in microsomal incubates. The apparent K-m,K-app and V-max,V-app for norfentanyl formation were 82 +/- 21 mu M and 4.7 +/- 0.4 nmol product formed/min/nmol cytochrome P450, respectively. Thus, this study defined methodology that can be used to evaluate the metabolism of fentanyl, both in vivo and in vitro, at clinically relevant concentrations.