SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists

A33
EVALUATION OF BUPRENORPHINE CEDIA ASSAY USING SAMPLES FROM PATIENTS IN
SUBSTITUTION TREATMENT
Michael Bottcher and Olof Beck*. Arztpraxis f. Medizinische Mikrobiologie, Labordiagnostik & Hygiene,
Dessau, Germany. Department of Medicine, Division of Clinical Pharmacology, Karolinska University
Hospital, Stockholm, Sweden.
Buprenorphine is used as an analgesic drug, and for detoxification and substitution therapy of opioid
dependence. However, in combination with the increased medical use, buprenorphine also occurs on the
black market as an illicit drug and fatalities due to poly-drug use has been reported. In addition, pausing
from buprenorphine intake during opiate relapsing has been observed and can make compliance monitoring
necessary. As a consequence there is a need for analytical service and toxicological monitoring of patients.
However, there has been a lack of an immunoassay suitable for automated high-volume screening. The aim
of this study was to evaluate the prototype buprenorphine CEDIA (Microgenics Inc.) by comparing it with
existing ELISA (Diagnostix Ltd) and GC-MS methods. Urine samples were collected from patients in
heroin substitution treatment with methadone, buprenorphine or dihydrocodeine. In total, 1552 samples
were obtained from approximately 600 patients, consisting of 70% males and having an age range of IS-54
y. The CEDIA test was performed on Hitachi 911 and 912 (Roche Diagnostics, IN) instruments with a
semiquantitative test protocol (five calibrators in the range 0-7S IlglL, sample volume 10 ilL) supplied by
Microgenics Inc. Samples with response >75 Ilg/L were diluted 10- or 100-fold with saline ..
At the levels exceeding the 5 Ilg/L cutoff level, a variability lower than 10% was observed both within- and
between-ctays. The correlation of CEDIA and ELISA was studied in 221 samples. There was a 96.S %
agreement in qualitative results between the methods. In three samples (2.7 % of all positives) CEDIA
produced a false positive response as the GC-MS confirmation was clearly negative. In one sample the
CEDIA result was false negative as the sample contained 26 Ilg/L of buprenorphine according to GC-MS.
The agreement between the CEDIA and GC-MS methods in quantifying buprenorphine was studied in the
range from 0 to 6000 Ilg/L. The samples were obtained from 72 patients receiving buprenorphine doses
between 0.5 - 25 mg/day. The slope was 1.09 with an intercept of -12 on the CEDlA axis. The median ratio
between CEDIA and GC-MS was 0.96 (n=29S). By pooling data for all samples with a buprenorphine
concentration >5 Ilg/L according to GC-MS or ELISA (n=400), the sensitivity for CEDIA of detecting
positive samples at the cutoff level of 5 Ilg/L was calculated to be 99.5%. A total of 1011 samples from
patients who were not receiving prescribed buprenorphine but received other heroin substitution treatments
(mainly methadone) were used to estimate specificity. Thirty samples (3.0 %) were found to be positive by
CEDIA at the cutoff level of 5 Ilg/L. One of these had detectable buprenorphine by GC-MS but at a low
level (0.6 Ilg/L). Fourteen of the 30 samples were from patients prescribed dihydrocodeine and contained
high amounts of this substance and metabolites. A further 20 samples from patients prescribed
dihydrocodeine in daily doses of 14 -SO mg were therefore studied and all were positive in the CEDlA
assay with responses ranging from 5 - 34 IlglL. The 15 false positive samples out of the 1011 (1.5%) all
had a low response «10) and all expect for one were highly positive in the CEDI A test for opiates,
indicating that a cross-reactivity with codeine can be suspected.
In conclusion, the new CEDI A assay for buprenorphine is suitable for use in clinical routine testing at a
cutoff limit at 5 Ilg/L.
Key words: Buprenorphine, Urine, CEDI A
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