Measurement of cyclosporine in plasma of cardiac allograft recipients by fluorescence polarization immunoassay.
The Abbott TDx fluorescence polarization immunoassay (FPIA) procedure for measuring cyclosporine A (CsA) was evaluated and compared with the Sandoz polyclonal radioimmunoassay (CsA RIA kit) method. This drug assay was evaluated for precision, calibration, stability, and accuracy. Within-run precision studies utilizing 25 replicate analyses of the three control preparations (containing CsA in the 60-800 ng/ml range) resulted in coefficients of variation (CV) ranging from 1.0 to 9.1%. The CVs of between-run precision determined by assaying the same control drug levels for five consecutive working days ranged from 3.9 to 4.6%. Calibration curve stability was assessed by examining the drift in control values over a 2-week period. Maximum plasma ranged from 82.6 to 108.2%. Four hundred plasma samples were obtained from 30 heart-transplant patients during the first 6 months of CsA therapy and each sample was analyzed simultaneously by TDx and RIA. Linear regression analysis of the results obtained for each patient (x = RIA, y = FPIA) revealed the following mean values: r = 0.87, (CV = 13.7%), slope = 1.47 (CV = 39.2%). Moreover, the concentration of CsA was determined in 35 patient samples both by TDx and high-performance liquid chromatography (HPLC). FPIA results up to 12 times higher than HPLC results have been noted.
Rondanelli
R
R
Department of Pharmacology, IRCCS, Policlinico S. Matteo, Pavia, Italy.
Regazzi
M B
MB
Gastaldi
L
L
Legnazzi
P
P
Abelli
P
P
D002851:Chromatography, High Pressure Liquid; D003524:Cyclosporins / Q000097:blood*; D005454:Fluorescence Polarization; D005455:Fluorescent Antibody Technique; D016027:Heart Transplantation; D006801:Humans; D008875:Middle Aged; D011863:Radioimmunoassay
D003524:Cyclosporins