A HIGHLY SENSITIVE ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR THE DETERMINATION OF TACROLIMUS IN ATOPIC-DERMATITIS PATIENTS

A highly sensitive enzyme-linked immunosorbent assay method has been d eveloped for the determination of tacrolimus in human blood samples. T he assay is a modification of the previously published assay with impr oved sensitivity. Following extraction of tacrolimus with methanol and sulfosalicylic acid, the samples are incubated for 2 h at room temper ature on a Nunc Maxisorb plate that has been treated for nonspecific b inding by precoating with polyclonal antibody, The analysis of human b lood following the standard addition of tacrolimus (0.02-5.0 ng/ml) de monstrated excellent precision and accuracy over a B-day period. The i nterday and intraday coefficients of variation were 6.0-28.9 and 3.9-1 5.2%, respectively. The limit of quantitation was 0.05 ng/ml. The meth od was used to quantitate blood concentration of tacrolimus in patient s following the administration of tacrolimus ointment.