| Summary: | 碩士 === 輔英科技大學 === 醫事技術系碩士班 === 97 === Immunoassays (IAs), sensitive with no sample pretreatment
requirement, are commonly used as the preliminary test method in drug testing. Enzyme-linked immunosorbent assays (ELISA), a conveniently packaged form of IA, for ketamine (the most popular new drug of abuse in Taiwan) and buprenorphine (an agent for treating heroin addiction) from
various sources were studied for their performance characteristics and suitability in pairing with GC-MS for effective application in workplace drug testing programs.
Following studies on the cross-reacting and calibration characteristics of commercially available IAs, those found favorable were applied to the analysis of urine specimens.
ELISA for ketamine from International Diagnostic Systems (IDS) was found to respond significantly to the metabolites of ketamine (norketamine and dehydronorketamine), while the reagent from Neogen responded very specifically to ketamine. Test data derived from the latter reagent exhibited better correlation with the ketamine concentration as determined by GC-MS; thus, it can be more reliably used as the preliminary test method in the 2-step approach, now routinely adapted in workplace drug testing programs. Using 100 ng/mL ketamine as the GC-MS cutoff, the corresponding ELISA cutoff value is approximately 110–120 ng/mL.
All ELISA and one analyzer-based immunoassay for buprenorphine included in this studied exhibited low cross-reactivity toward opioids, such as morphine, codeine, hydrocodone, hydromorphone, and oxycodone. However, they showed dissimilar cross-reactivities toward different
buprenorphine metabolites, resulting in better correlation to the concentrations of different analytes as determined by GC-MS. Responses derived from three ELISA and the analyzer-based IAs were found to correlate to the total concentration of buprenorphine (buprenorphine plus buprenorphine glucuronide), while the response of ELISA from Immunalysis was found to correlate with the concentrations of buprenorphine plus norbuprenorphine. The analyzer-based IA exhibits a wider calibration range and higher sensitivity. This product was studied further and found to generate an apparent concentration of approximately 60 ng/mL for specimens containing 50 ng/mL of buprenorphine.
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