Doxylamine

Abstract
A 25-yr-old white woman ingested an unknown quantity of doxylamine succinate and flurazepam. Urine immunoassay screen (EMIT[enzyme multiplied immunoassay technique]-dau) was positive for benzodiazopine and negative for phencyclidine. Subsequent gas chromatographic assay of the urine revealed a markedly positive assay for phencyclidine. Doxylamine was the cause for the false-positive gas chromatographic assay for phencyclidine.