LZI Fentanyl III Enzyme Immunoassay

The LZI Fentanyl III Enzyme Immunoassay is a homogeneous enzyme immunoassay kit for qualitative detection of fentanyl in human urine at a 1 ng/mL cutoff. It uses glucose-6-phosphate dehydrogenase (G6PDH) labeled with fentanyl and a monoclonal anti-fentanyl antibody to produce measurable absorbance changes. The assay is designed for prescription use with automated clinical chemistry analyzers and provides preliminary results requiring LC/MS confirmation.

The subject device differs from the predicate (LZI Fentanyl II) in target analyte (fentanyl vs. norfentanyl), cutoff concentration (1 ng/mL vs. 5 ng/mL), calibrator and control levels, and application volumes (R1: 65 µL vs. 120 µL; R2: 25 µL vs. 45 µL). Both use identical detection principles (spectrophotometry at 340 nm), two-reagent liquid systems with sodium azide preservative, and require automated analyzers. Matrix, storage, user environment, and confirmation requirements are the same.

Not stated in this summary. The document references a modified NCCLS-EP5 protocol for precision testing and LC/MS as a confirmation method, but does not cite specific consensus standards (ISO, IEC, ASTM).

Substantial equivalence is demonstrated through method comparison with 150 clinical samples showing 100% negative/positive accuracy agreement away from the cutoff region; discrepant samples (32 of 150) contained norfentanyl that cross-reacted with the assay, expected for an anti-fentanyl antibody. Precision studies across 88 replicates showed consistent positive/negative calls. Extensive cross-reactivity testing of 40+ fentanyl analogues and 100+ unrelated compounds identified minimal clinically significant interference (dextromethorphan at 20,000 ng/mL and boric acid at 1% w/v). The device uses identical assay principle, reagent chemistry, and platform as the predicate, with only parameter changes proportional to the new 1 ng/mL cutoff versus the predicate's 5 ng/mL cutoff.