Evaluation of the Triage PPY On-Site Testing Device for the Detection of Dextropropoxyphene in Urine

A new point-of-care colloidal metal immunoassay urine drugs-of-abuse testing device, the BIOSITE TRIAGE® Plus Propoxyphene (TPP), was evaluated for the rapid detection of dextropropoxyphene (PPY) and/or its primary metabolite, norpropoxyphene (NP), in urine at a total PPY/NP concentration of 300 ng/mL or greater. This assay has been added to the Triage device that tests for commonly abused drugs. Adding to drug-free urine PPY and NP established the linearity of the TPP assay at concentrations of 40%, 80%, 120%, and 160% of the cut-off concentration. No significant cross-reactivity was found at 1.0 g/L for 32 drugs commonly encountered in emergency department admissions. Significant cross-reactivity was observed only with diphenhydramine and tricyclic antidepressants. TPP results from 160 urine specimens screened for PPY and/or NP were compared to those obtained by testing with DRI® enzyme immunoassay, Emit II plus immunoassay, Abuscreen® Online immunoassay and gas chromatography-mass spectrometry (GC-MS). There was a 98.8% agreement of positive or negative results between TPP and both the DRI and OnLine assays. The two discordant TPP results were due to concentrations of NP below the TPP minimum cross-reactivity value of 400 ng/mL. These two specimens yielded GC-MS NP concentrations of 262 and 359 ng/mL. These NP concentrations were within ± 20% of the cross-reactivity cut-off value for NP for TPP, DRI, and Online. There was only an 88% agreement of positive or negative results between TPP and the Emit assay. Twenty urine specimens yielding PPY positive results when tested by TPP were negative by Emit testing. The discordant TPP results were due to poor cross-reactivity of Emit to NP. A 98.8% agreement of positive PPY results was observed between TPP and GC-MS. Discordant urines were found to contain PPY concentrations below the cut-off value of the assay. TPP was found to be an accurate device for the detection of PPY and NP in urine.