title: Immunoassay screening of diphenhydramine (Benadryl®) in urine and blood using a newly developed assay.
abstract: Diphenhydramine (DPH) is a common over the counter antihistamine that produces drowsiness and has the potential to cause driving under the influence of drugs-related accidents. To date there are no commercially available immunoassay screening kits for its detection in biological fluids such as urine and/or blood. We describe a newly developed enzyme-linked immunosorbent assay (ELISA) screen and report on its utility in the analysis of authentic specimens taken from volunteers. The assay is specific for detection of DPH and does not detect closely related antihistamines like brompheniramine, chlorpheniramine, and doxylamine. There is a varying amount of cross-reactivity seen with certain tricyclic compounds, due to similarities in side chain structure with DPH. Intra- and interday precision of the assay were determined to be less than 10%. The assay is highly sensitive and has a working range from 1 to 500 ng/mL for urine and 1 to 250 ng/mL for blood. The assay was further validated with authentic urine and blood specimens obtained from volunteers and coroner's laboratories.
authors.affiliation: Immunalysis Corporation, Pomona, CA 91767, USA. wrodrigues@immunalysis.com
authors.forename: Warren C
authors.initials: WC
authors.lastname: Rodrigues
authors.forename: Catherine
authors.initials: C
authors.lastname: Castro
authors.forename: Philip
authors.initials: P
authors.lastname: Catbagan
authors.forename: Christine
authors.initials: C
authors.lastname: Moore
authors.forename: Guohong
authors.initials: G
authors.lastname: Wang
mesh_terms: D001977:Brompheniramine / Q000097:blood; D002744:Chlorpheniramine / Q000097:blood; D004155:Diphenhydramine / Q000097:blood* / Q000652:urine*; D004319:Doxylamine / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006633:Histamine Antagonists; D006801:Humans; D015203:Reproducibility of Results; D013048:Specimen Handling
chemical_list: D006633:Histamine Antagonists; D002744:Chlorpheniramine; D004155:Diphenhydramine; D004319:Doxylamine; D001977:Brompheniramine