To the Editor.—
The contribution by Weddington and Carney1 in the June 26, 1987, issue of JAMA entitled "Alprazolam Abuse and Dependence" demands my comments.In their Letter, the authors state that the usual urine toxicology screens for benzodiazepine metabolites give falsenegative results after alprazolam (Xanax) ingestion because alprazolam and metabolites are excreted in amounts below the detection limits of the assay. The authors did not state what screening method was used.
Pure standards of alprazolam and αOH alprazolam were analyzed, in the Toxicology Laboratory, Victoria General Hospital, by the enzyme-multiplied immunosorbent (EMIT d.a.u.) assay. Both standard solutions gave an equivalent response to the EMIT low calibrator at 0.2 to 0.3 μg/mL.Random urine specimens from 27 inpatients receiving 0.25 to 7.0 mg/d of alprazolam (Xanax) were analyzed by the standard EMIT protocol for benzodiazepine metabolites. In this study, 24 of the specimens were positive (ie, reading greater