We report that use of the popular analgesic tramadol can cause false-positive urine buprenorphine results. We examined the extent of tramadol cross-reactivity in three point-of-care urine buprenorphine immunoassays (ACON, QuikStrip, and ABMC) and an instrument-based one (Cedia). We tested 29 urine samples from patients known to be taking tramadol. Ten different samples tested positive for urine buprenorphine by at least one immunoassay. Samples with positive buprenorphine screens by immunoassay were tested for total buprenorphine and total norbuprenorphine content by liquid chromatography-tandem mass spectrometry (LC-MS-MS), which confirmed that seven of the 10 positive samples were false-positives. The remaining three positive immunoassay samples had insufficient quantity for LC-MS-MS testing. No false-positives were detected with the ACON (10 ng/mL calibration cutoff) or the Cedia assay (using a 20 ng/mL calibration cutoff). All four false-positive Cedia results (using a 5 ng/mL cutoff) in this study tested negative using the ACON device. Our data suggest that tramadol use can cause false-positive urine buprenorphine immunoassays, and this effect appears to be assay-dependent. Tramadol interference with the Cedia assay is clinically relevant, especially if the 5 ng/mL calibration cutoff is used.
BACKGROUND:We implemented oral fluid (OF) as an alternative specimen type to urine for detection of cocaine (COC) and opiate abuse in outpatient addiction medicine clinics.
This paper was prepared for the 44th Annual Fall Meeting of the of the Society of Petroleum Engineers of AIME, to be held in Denver, Colo., Sept. 28-Oct. 1, 1969. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal, provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract Single-phase gas flow in two space dimensions in a reservoir is described by a non-linear partial differential equation. In order to solve this equation for meaningful reservoir problems, recourse is generally taken to a digital computer and numerical techniques of solution. The alternating direction implicit procedure (ADIP), combined with iteration procedure (ADIP), combined with iteration because of the non-linearity of the equation, is applicable. This paper describes the implementation of the ADI procedure on a hybrid computer. In this approach the time derivitive in the equation is integrated continuously over finite time steps using the analog portion of the hybrid. Basically, this integration replaces the Thomas or other algorithm required for the solution of the matrix generated in the formation of finite difference equations. By this new method the non-linear coefficients in the equation can be included directly in the analog integration, thus eliminating the necessity of iteration as required in digital algorithms. In this initial implementation of the procedure, the reservoir is assumed procedure, the reservoir is assumed homogeneous and gas properties (viscosity, compressibility factor) are assumed to be constant. However, the technique as described is quite general and can be extended to non-ideal gases and non-constant coefficient equations. Introduction Mathematical description of single-phase gas flow in a reservoir gives rise to a second order non-linear partial differential equation. The solution of this equation provides the engineer with useful information provides the engineer with useful information for analyses of gas field well test, the design of gas field drilling programs, gas storage reservoir design, etc. Since the gas flow equation is non-linear, analytical solutions are not readily available. However, many approximate solutions for the case of one-dimensional radial flow have been presented. Such papers have been especially useful for the design and interpretation of flow tests. For systems of more complicated geometry or heterogeneous systems it has been necessary to resort to numerical techniques, applied using a digital computer. In an early paper Bruce et. al. solved the gas flow equation numerically in one space dimension.
Buprenorphine (BUP), a partial opioid agonist, is used in outpatient settings to treat opioid addiction and manage chronic pain. Patients in these settings are increasingly screened for the presence or absence of BUP in their urine to monitor medication compliance and to detect and deter misuse of this potent drug. We evaluated 3 point-ofcare (POC; ACON, NTB, and ABMC) and 2 automated urine BUP qualitative immunoassays (CEDIA and LZ) for their ability to accurately detect BUP in 52 urine (17 positive/35 negative) samples from patients treated for chronic pain. Sensitivity and specificity of each assay were evaluated in comparison with a liquid chromatographyYtandem mass spectrometry BUP reference method. Overall agreement with liquid chromatographyYtandem mass spectrometry for these 52 samples, many of which contained low levels of BUP and high concentrations of potentially cross-reacting drugs, was 77%, 73%, 65%, 48%, and 85% for ACON, NTB, ABMC, CEDIA, and LZ, respectively. The NTB POC and automated CEDIA assays were able to detect lower BUP levels and had higher sensitivities, 88% and 94%, respectively, compared with the ACON (29%), ABMC (29%), and LZ (53%) assays. However, the NTB POC, CEDIA, and ABMC POC generated a substantial number of false positives, providing considerable lower specificities of 66%, 26%, and 83%, respectively, compared with the ACON POC and automated LZ methods (both 100%). Of the 3 POC assays, ACON demonstrated the best overall performance, allowing reliable detection of BUP above its stated cutoff without interference from other opioid-related compounds.
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