A dry-reagent strip for quantifying carbamazepine evaluated.

We examined a new colorimetric homogeneous immunoassay for carbamazepine based on the apoenzyme reactivation immunoassay system (ARIS) principle. The test, in dry-reagent strip format, is to be used with the Ames Seralyzer reflectance photometer. Within-run CVs (n = 20) were 3.0%, 2.7%, and 2.8% at 3.0, 6.1, and 12.1 mg/L; between-run CVs (n = 15, in 15 days) were 4.1%, 2.7%, and 1.9% at 6.0, 9.1, and 12.1 mg/L. Mean analytical recovery was 99.9 (SD 2.3)%. Results by this test (y) for clinical plasma specimens (n = 96) compared very well with those obtained by fluorescence polarization immunoassay (y = 1.01 x - 0.02, r = 0.995) and by liquid chromatography (y = 0.99 x + 0.14, r = 0.990). Bilirubin (45 mg/L), uric acid (145 mg/L), and various anticoagulants at about fourfold the usual concentrations did not interfere. High concentrations of cholesterol (4.9 g/L), triglycerides (3.8 g/L), and hemoglobin (4 g/L) caused slight positive interference. Carbamazepine-10,11-epoxide cross reacted only at greater than or equal to 5 mg/L. The two-point calibration line was validly stored for at least three weeks. Free carbamazepine also can be measured. The test is convenient and rapid (test time 80 s), and thus is particularly useful in all clinical settings where prompt testing is needed.