At the time the testing presented in the McIntyre et al. paper (1) was ... Christine Moore and Michael Vincent ... I.M. McIntyre, J.L. Sherrard, and C.L. Nelson.
Journal of Analytical Toxicology, Vol. 34, March 2010
Letter to the Editor
Improved Oxymorphone Detection in Postmortem Specimens* To the Editor: In the November/December 2009 issue of the Journal of Analytical Toxicology, McIntyre et al. (1) discussed the determination of oxymorphone in postmortem blood specimens following ELISA screening. The authors discuss the low crossreactivity of the general opiates assay with oxymorphone (20% at 125 ng/mL oxycodone equivalents), which caused the blood screening results in these cases to be negative. Oxymorphone is now widely available as a prescribed medication (Opana®) as well as being the primary metabolite of oxycodone. In response to the increased availability of oxymorphone, and the need for an improved detection rate for oxymorphone screening assays, an enzyme immunosorbent assay (ELISA) was developed towards oxycodone, with a crossreactivity for oxymorphone of 88% (at 25 ng/mL oxycodone equivalents), and 90% (at 50 ng/mL oxycodone equivalents). The assay has extremely low cross-reactivity to other opioids (< 10%) such as noroxycodone, morphine, codeine, dihydrocodone, hydrocodone, hydromorphone, normorphine, norcodeine, meperidine, naloxone, nalbuphine, tramadol, and trazodone. In addition, the sensitivity of oxycodone detection was improved, so a cutoff concentration of 10 ng/mL is easily achievable using a 10-μL aliquot of a blood sample diluted 1:10. Because ELISAs can be used with virtually any matrix, postmortem specimens, including urine, can be analyzed using the kit as long as appropriate dilutions are made. At the time the testing presented in the McIntyre et al. paper (1) was performed, the assay was not available, and it has only recently been introduced as an additional tool for toxicologists in the analysis of oxymorphone. Neogen also manufactures an Oxycodone/Oxymorphone ELISA kit (Catalog # 130719) that claims 88% cross-reactivity with oxymorphone and cross-reactivities of 27% and 21% for hydrocodone and hydromorphone, respectively. Other opioids were less than 10%.
Christine Moore and Michael Vincent Immunalysis Corporation Pomona, California
References 1. I.M. McIntyre, J.L. Sherrard, and C.L. Nelson. Oxymorphone-involved fatalities: a report of two cases. J. Anal. Toxicol. 33: 615–619 (2009). 2. ELISA kit-221B. Oxycodone/Oxymorphone Direct ELISA Blood Package Insert. August 2009. Immunalysis Corporation, Pomona, CA.
* Conflict of interest statement: Both authors are employed by Immunalysis Corporation, manufacturer of the ELISA kit described.
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