Can an Immunoassay Become a Standard Technique in Detecting Oxycodone and Its Metabolites?

Abstract

Opiate toxicology testing is routinely performed in the hospital setting to identify abusers and/or to determine those patients who are not taking prescribed opiate analgesics such as oxycodone. Commercially available assays for opiate detection in urine have decreased sensitivity for oxycodone, which contributes to a high false-negative rate. Functioning as a beta site, our Veterans Affairs hospital evaluated a new enzyme immunoassay, DRI Oxycodone Assay, for its use in the qualitative and semiquantitative detection of oxycodone in urine. We hypothesize that an immunoassay for oxycodone with superior sensitivity and specificity, when compared to the traditional opiate assays, would reduce the need for more expensive and time-consuming confirmatory testing. We used the new liquid homogenous enzyme immunoassay to determine oxycodone results in a total of 148 urine samples from 4 different sample groups. Gas chromatography-mass spectroscopy was subsequently used to confirm the presence or absence of oxycodone (or its primary metabolite, noroxycodone). We also evaluated within-run, between-run, and linearity studies and conducted a crossover study to establish a cutoff value for oxycodone. In our patient population, we used the new DRI immunoassay to evaluate 17,069 urine samples to estimate oxycodone misuse profiles (patients not taking prescribed oxycodone or taking oxycodone without a prescription) during a 4-month period. The sensitivity and specificity of the new oxycodone immunoassay were 97.7% and 100%, respectively, at the cutoff concentration of 300 ng/mL. The assay linearity was 1,250 ng/mL, and the sensitivity was 10 ng/mL. Within-run precision and between-run coefficient of variation were 2.3% and 1.8%, respectively. None of the 15 compounds that we evaluated for interference had crossover significant enough to produce a positive oxycodone result when using 300 ng/mL as the cutoff value. None of the 17,069 oxycodone immunoassays was followed with a request for confirmation. Among patients with positive results (n = 224), 93 (41.5%) were not prescribed oxycodone. The new DRI Oxycodone Assay is a sensitive and specific screening test for the determination of oxycodone. The improved opiate screening results may lead to better patient and prescription management, to decreased laboratory spending, and to the identification of oxycodone abusers, which could result in decreased oxycodone-related mortality.

Comparison of Response of DRI Oxycodone Semiquantitative Immunoassay With True Oxycodone Values Determined by Liquid Chromatography Combined With Tandem Mass Spectrometry: Sensitivity of the DRI Assay at 100 ng/ml Cut‐Off and Validity of Semiquantitative Value

“…If a test is positive it may be confirmed by a chromatographic technique but no further testing may be offered if the initial screening test is negative. Abadie et al commented that the DRI oxycodone immunoassay could be used as a standard technique in detecting oxycodone and its metabolite as none of the 17,069 oxycodone immunoassays results were followed with request for confirmation using gas chromatography‐mass spectrometry . Backer et al commented that the DRI oxycodone assay at a 100 ng/ml cutoff is a highly reliable method for the detection of oxycodone and oxymorphone in urine specimen .…”

Evaluation of ongoing oxycodone abuse among methadone-maintained patients

“…The laboratory methods used for detecting opioid use in clinical settings often are designed to detect morphine and codeine and may have poor sensitivity for some synthetic and semisynthetic opioids, resulting in the high probability of false-negative results in the presence of oxycodone and other similar drugs (Haller et al, 2006). Assays capable of detecting the presence of oxycodone and other prescription opioids in urine are just beginning to become more widely available (Backer, Monforte & Poklis, 2005;Haller et al, 2006), and at least one recent report has advocated for the use of these newer prescription opioid assays in clinical settings (Abadie et al, 2005). Despite this, most methadone clinics and other drug treatment programs in the United States likely have not yet added a specific oxycodone assay to their urinalysis testing methods and may instead rely on general opiate assays that detect a variety of opiates but often have relatively poor sensitivity for oxycodone in particular.…”

Label-Free Porous Silicon Immunosensor for Broad Detection of Opiates in a Blind Clinical Study and Results Comparison to Commercial Analytical Chemistry Techniques

“…In addition, special attention has been made to evaluate the capability of the PSi opiate biosensor to detect oxycodone. Oxycodone in a time-release preparation as OxyContin is among the most often-prescribed schedule II controlled substances for pain relief, and its widespread availability and high dependency potential have contributed to its “street” sale and frequent abuse. , Oxycodone is a semisynthetic opiate chemically related to morphine and codeine that contains a 6-keto substituent group and a hydroxyl group at carbon 14 . Most commercial opiate immunoassay kits are designed to detect morphine and codeine and have limitations for oxycodone detection. − Thus, oxycodone-specific immunoassays have been developed for use in pain clinics and/or as a secondary opiate screening test in clinical laboratories .…”

“…Oxycodone in a time-release preparation as OxyContin is among the most often-prescribed schedule II controlled substances for pain relief, and its widespread availability and high dependency potential have contributed to its “street” sale and frequent abuse. , Oxycodone is a semisynthetic opiate chemically related to morphine and codeine that contains a 6-keto substituent group and a hydroxyl group at carbon 14 . Most commercial opiate immunoassay kits are designed to detect morphine and codeine and have limitations for oxycodone detection. − Thus, oxycodone-specific immunoassays have been developed for use in pain clinics and/or as a secondary opiate screening test in clinical laboratories . The use of a broad opiate screening assay that includes sensitive detection of oxycodone and its metabolites would be advantageous in a clinical setting, decreasing false negative screening results and decreasing the cost and time associated with secondary more-specific oxycodone screening techniques.…”

“…Oxycodone in a time-release preparation as OxyContin is among the most often-prescribed schedule II controlled substances for pain relief, and its widespread availability and high dependency potential have contributed to its "street" sale and frequent abuse. 27,28 Oxycodone is a semisynthetic opiate chemically related to morphine and codeine that contains a 6-keto substituent group and a hydroxyl group at carbon 14. 24 Most commercial opiate immunoassay kits are designed to detect morphine and codeine and have limitations for oxycodone detection.…”