ARCHITECT iGentamicin

The ARCHITECT iGentamicin is an automated in vitro chemiluminescent microparticle immunoassay (CMIA) that measures gentamicin antibiotic levels in human serum or plasma. It is used to diagnose and treat gentamicin overdose and to monitor therapeutic drug levels on the ARCHITECT iSystem analyzer with STAT protocol capability.

The subject device is substantially identical to the predicate in intended use, specimen type, measurand, instrument platform, assay technology, measuring interval (0.3–10.0 μg/mL), and reagent packaging. Minor formulation differences exist: microparticle solids reduced from 0.20% to 0.13%, conjugate tracer concentration lowered from 4 ng/mL to 3.4 ng/mL, detergent changed from Triton X-100 to Tergitol 15-S-9, and conjugate tracer solvent changed from dimethylformamide to dimethyl sulfoxide.

Performance studies used Clinical and Laboratory Standards Institute (CLSI) guidance documents: EP05-A3 (precision), EP34 (recovery/extended measuring interval), EP17-A2 (detection limits), EP06 (linearity), EP07 (interference testing), EP37 (interference supplemental tables), EP09-A3 (method comparison), and EP25-A (stability and drift).

The subject device demonstrates substantially equivalent performance through comparative testing showing comparable within-laboratory precision (3.7–6.0% CV), accuracy recovery (104.6% mean), and linear performance across the claimed range. Method comparison to the predicate using three reagent lots yielded correlation coefficients ≥0.99 with slopes and intercepts within clinically acceptable ranges. Stability and on-board drift data support the same 12-month shelf life. Although formulation changes were made, performance remains equivalent, and known cross-reactivity with tobramycin and other aminoglycosides is disclosed in labeling consistent with the predicate.