Using molecular similarity to highlight the challenges of routine immunoassay-based drug of abuse/toxicology screening in emergency medicine

Table 1 Drugs or drug metabolites that can produce false negatives on DOA/Tox screening immunoassays

			Cross-Reactivity to Marketed Immunoassays
Drug	Assay¹	Similarity to assay target compound²	Abbott³	Beckman³	Biosite Triage³	Microgenics³	Roche³	Siemens³
MDMA	AMPH	0.361	1,300	2,500	2,000	1,300	697,000	34,300
Alprazolam	BENZO	0.610	113	300	450	25	219	65
Clonazepam	BENZO	0.656	214	300	350	3,000	307	260
Clonazepam metabolite (7-amino)	BENZO	0.755	2,334	800	7,500	1,000	288	5,700
Clobazam	BENZO	0.796	218	500	700	250	237	260
Buprenorphine	OPIA	0.783			No effect			No effect
Oxycodone	OPIA	0.800	No effect	17,000	20,000	16,000	> 75,000	2,550
Oxymorphone	OPIA	0.847	No effect	No effect	40,000	40,000		> 20,000
Amoxapine	TCA	0.508	No effect		No effect	No effect		No effect

¹ Assay abbreviations: AMPH, amphetamines; BENZO, benzodiazepines; OPIA, opiates; TCA, tricyclic antidepressants.
² Target compounds: AMPH, d-amphetamine; BENZO, diazepam; OPIA, morphine; TCA, desipramine. Similarity calculated using MDL public keys with Tanimoto coefficient.
³ Concentration of compound in ng/mL that produces cross-reactivity equal to 1,000 d-amphetamine (AMPH assay), 200 ng/mL diazepam (BENZO assay), 300 ng/mL morphine (OPIA assay), or 1,000 ng/mL desipramine (TCA assay). Blank cells indicate that no cross-reactivity data is reported. For all assays except TCA, marketed assays are for Abbott Architect, Beckman, Biosite Triage, Microgenics DRI, Roche cobas c, and Siemens Syva EMIT systems. For TCA, marketed assays are Abbott AxSYM, Biosite Triage, Microgenics DRI serum, and Siemens Syva EMIT systems. See Additional file 1 (tab T) for more details.

ISSN: 1471-227X