This is what I have found.
Here is the link to the entire article to take to your doc and show him that false negatives are a common problem for detection of oxycodone use which falsely acuses patients of diversion.
This is probaly going to exceed 10,000 characters because I copied 3 different articles that pretty much all said the same thing. Your doc and the lab may not even be aware of the problems involved in proper Oxycodone testing.
Only when this test is done for exclusion of employment or termination of employment would a lab need to do the confirmation with GC-MS to prevent a law suit for wrongful terminination for not doing the confirmation with GC-MS
As long as you haven't diluted your urine beyond 300ng per ml of urine. "300 nanograms per ML" Which wouldn't be hard to do, People have been fooling UA's for years simply by flushing their system and guzzling water. IF the UA doesn't show oxy in your system in a case of patient compliance, then a GS-MS test needs to be preformed to confirm the presumptive UA. I would bet thousands of people have lost their jobs or been denied employment without confirming the presumptive test due to the cost of the GS-MS testing procedure.
Most laboratories use commercially available immunoassays to screen for opiates in urine. They do not normally confirm presumptive positive screening tests. These immunoassays were designed to detect use of the opiates - heroin, codeine and morphine but not other opiates such as hydromorphone, hydrocodone and oxycodone, etc. Clinicians and other users of laboratory services are often unaware that opiate screening methods are unable to reliably detect oxycodone use/abuse. Because of the potent analgesic effects of oxycodone, this drug is often used in pain clinics.
In 2001, medical directors of pain management centers in Canada were concerned about oxycodone diversion, i.e. selling on the street, by some of their patients. Because of these concerns, urine drug screens were ordered in several smaller centers. Since the test results might be "negative" for oxycodone screening., individual patients could be wrongfully identified as diverting their prescription drugs to others. To resolve these concerns, urine specimens must be analyzed specifically for oxycodone by GC/MS or another robust methods in order to obtain an accurate indication of oxycodone use by these patients. Further, clinical and forensic laboratories may be unaware that one cannot adequately screen for oxycodone use by commercially available opiate immunoassays. In areas where oxycodone abuse is known or suspected, laboratories providing blood and/or urine drug screening services should alert their users about the limitations of their ability to screen for oxycodone. Thus, the emergence of oxycodone as a popular drug of abuse highlights the importance of on-going communication between the laboratory and the end users. The laboratory should update the users on the advantages and limitations of blood or urine drug testing.
Oxycodone can be extracted from biological fluids by either liquid/liquid extraction or more recently, solid phase extraction techniques. Solid phase extraction techniques utilize C18, C8, or copolymeric columns. For greater sensitivity and detection, enzymatic hydrolysis with beta-glucuronidase can be used to increase the recovery of oxycodone from biological fluids.
Methods used for the detection of 6-keto-opioids, such as oxycodone, include commercial immunoassays, thin-layer chromatography (TLC), liquid chromatography (LC), automated liquid chromatography (REMEDi), liquid chromatography-mass spectrometry (LC/MS), gas chromatography (GC), and gas chromatography-mass spectrometry (GC/MS). Despite the numerous techniques, only gas or liquid chromatography coupled with mass spectrometry is the acceptable confirmation technique for quantification of opiates - morphine and codeine ( Note - oxycodone is not currently included as one of the SAMHSA analytes ) in urine according to the Department of Health and Human Services (DHHS) guidelines for drug testing of federal employees (12).
In general, immunoassays are not well suited for the detection of 6-keto-opioids, such as oxycodone, due to the low antibody cross-reactivity of the commercial opiate kits. Cone et al. showed that each of the 6-keto-opioid compounds had concentration-dependent cross-reactivities in commercial opiate immunoassays, and each had the potential to produce positive urine screening results (13). Furthermore, Smith et al. compared several commercial immunoassays to GC-MS and demonstrated that oxycodone present in urine was detected by TDx® opiates (TDx; Abbott Laboratories) and the EMIT® d.a.u. opiate assay (EMIT; Syva) for 6-24 hrs. However, the quantitative responses from these assays expressed as ng/ml of morphine equivalents were substantially lower than GC/MS determinations (8). As a result, immunoassays are not well suited for monitoring the therapeutic use, compliance, or abuse of oxycodone. Therefore, it might be advisable to confirm any immunoassay screening tests with increased urine opiate concentrations by using a suitable chromatographic method.
Toxi-Lab ATM thin-layer chromatography (TLC) drug detection system can also be used for the detection of oxycodone in urine specimens. However, therapeutic dosages of oxycodone might be below the detection limit of this system at 1.0 mg/L in 5ml aliquots. However, Gobar et al. demonstrated that oxycodone in urine samples of pain management patients was detected by TLC and then confirmed by GC/MS with cutoff limits of 300 ng/ml for both assays (15). Furthermore, the sensitivity and specificity for both assays were 72.7 and 84.2%, respectively.
Oxycodone can also be detected and/or quantitated in biological fluids by gas chromatography with FID or NPD detection. Confirmation by GC/MS in the full scan mode shows principle peaks at m/z 315, 230, 70, 258, and 140. GC/MS utilizing selective ion monitoring (SIM) of principle ions will increase assay sensitivity so that detection limits of 10 ng/ml can be achieved. At these detection limits, therapeutic use, compliance, and oxycodone abuse can be monitored.
In GC/MS, the choice of derivatization agents is one of the most important factors in the accuracy and precision of the method. Many derivatizing agents can be used including acetic anhydride (16), bis-trimethylsilytrifluoroacetamide/trimethylsilyl (BSTFA/1% TMS) (17), heptafluorobutyric anhydride (HFBA) (17), pentafluoropropionic anhydride (PFPA) (17), and MBTFA (18). Problems encountered with some GC/MS methods include instability of derivatives, poor chromatography, unsuitable ions and abundances, incomplete derivatization, derivatization side reactions, inadequate recovery, loss during hydrolysis, extended run times, and interference or coelution of other opiates (19).
Recently, an improved GC/MS method for the simultaneous identification and quantification of opiates in urine was reported (20). In this method, methoxyamine was used after enzymatic hydrolysis to form methoxime derivatives of the keto-opiates, which were extracted using solid-phase columns and derivatized with propionic anhydride/pyridine. This method demonstrated acceptable precision, the lack of cross-interference from other opioids, short analysis time of about 6.5 min, and a small sample volume of 2.0 ml urine.
Finally, LC/MS has been used to determine the concentration of oxycodone in plasma (21). This method was selective and rapid with a analysis time of 2 min. A small sample volume of 1 ml plasma was alkalinized and extracted with 2% isoamyl alcohol in n-butyl chloride. After evaporation and reconstitution in 15% methanol-85% water containing 0.1% acetic acid, the sample was analyzed by LC/MS. The limit of quantification was 1 ng/mL., and the limit of detection, 33 pg/ml. In addition, this method was linear from 1 to 100 ng/mL. In comparison, an automated LC - REMEDi is capable of screening with a sensitivity of 150 ng/mL. However, the major problem is that oxycodone is eliminated quickly from the blood as a result of its short half-life.
Overall, the analysis and quantification of oxycodone is increasingly important as its use and abuse becomes more widespread. In addition, pharmacogenetic typing of individuals taking oxycodone may be recommended, because oxycodone is metabolized to oxymorphone by cytochrome (CYP) 450 2D6. This enzyme is polymorphic with a prevalence of three mutations *3, *4, and *5 in about 10% of the general population (22). In fact, 95% of individuals classified as poor drug metabolizers have one or more of these mutations. They are more likely to experience severe toxicity or therapeutic failure. Thus, pharmacogenomics, in the near future, might become an integral part of pain management to individualize oxycodone and other drug therapy with minimized adverse reactions.
1. Baselt, R.C., Disposition of Toxic Drugs and Chemicals in Man, Fifth Edition, Chemical Toxicology Institute, Foster City, CA, 2000, pp. 644-645.
Continued on next post, Shore
PS. If you have to take a test be able to ask what version your having done and will it be confirmed with GC-MS whch I highly doubt your insurance is going to pay for forensic testing of urine via GC-MS to simply detect abuse or diversion.