title: Cross-reactivity of selected compounds in the Abbott TDx cannabinoid assay.
abstract: Immunoassay procedures, both enzyme immunoassay and radioimmunoassay, continue to be widely used to screen samples for recent marijuana use by analyzing the urine samples for 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (11-nor-delta 9-THC-9-COOH) (the major urinary metabolite of delta 9-tetrahydrocannabinol [delta 9-THC]). Using commercially available immunoassay reagents, the cross-reactivity of the antiserum utilized in Abbott's TDx cannabinoid assay (a fluorescence polarization immunoassay) was evaluated. This cross-reactivity was evaluated against a group of cannabinoids and noncannabinoid phenolic constituents of Cannabis, some cannabinoid metabolites, and other agents that appear in normal urine samples. In general, the antiserum was equally reactive toward 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid, its glucuronide, and the corresponding delta 8-isomer, which was the acid moiety utilized in standards and controls of the assay prior to January, 1990. Reduced binding to the antiserum was observed with hydroxylated derivatives of delta 9- and delta 8-THC, and the other cannabinoids, in general, exhibited limited binding potentials toward the antibody. For the noncannabinoid constituents, no binding was observed at the highest concentrations evaluated (40 mg/L).
authors.affiliation: Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, University 38677.
authors.forename: M A
authors.initials: MA
authors.lastname: ElSohly
authors.forename: A B
authors.initials: AB
authors.lastname: Jones
authors.forename: H N
authors.initials: HN
authors.lastname: ElSohly
mesh_terms: D000918:Antibody Specificity; D002186:Cannabinoids / Q000652:urine*; D002188:Cannabis / Q000032:analysis; D003429:Cross Reactions; D013759:Dronabinol / Q000031:analogs & derivatives / Q000652:urine; D005069:Evaluation Studies as Topic; D005454:Fluorescence Polarization; D006801:Humans; D015813:Substance Abuse Detection
chemical_list: D002186:Cannabinoids; C016780:11-nor-delta(9)-tetrahydrocannabinol-9-carboxylic acid; D013759:Dronabinol