Determination of the bioavailability of intranasal elcatonin in humans: Development of a sandwich transfer enzyme immunoassay for elcatonin

摘要

A sandwich transfer enzyme immunoassay for elcatonin (ECT) and its usability for the pharmacokinetic study are described. The anti‐salmon calcitonin (SCT) antibody was used for the present assay. The assay procedure consisted of the reaction of ECT with 2,4‐dinitrophenylbiotinyl anti‐SCT IgG and anti‐SCT Fab′‐β‐ ‐galactosidase conjugate, trapping onto (anti‐2,4‐dinitrophenyl bovine serum albumin) IgG‐coated polystyrene balls, eluting with ϵ ‐2,4‐dinitrophenyl‐L‐lysine and transferring to streptavidin‐coated polystyrene balls and fluorometric detection of β‐ ‐galactosidase activity. The practical detection limit of ECT was 0.15 pg (44 amol)/50 μl of sample and 3 pg/ml as the concentration. The application of this method has enabled us to directly estimate the bioavailability of ECT dosed intranasaly at a therapeutic level (100 IU, 17 μg) for its anti‐osteoporotic effect as compared to an intramuscular dose (40 IU, 6.7 μg). The pharmacokinetic parameters of the intranasalECT (n = 6) thus estimated were as follows: the area under the serum concentration‐time curve (AUC) = 2,570 ± 1,650 (SD) pg × min/ml, and the maximal concentration (Cmax)= 60 ± 25 (SD) pg/ml with the maximaltime (Tmax) = 17.5 ± 6.9 (SD) min, when the AUC for the intramuscular ECT (n = 9) = 9,460 ± 5,870 (SD) pg × min/ml and the Cmax = 165 ± 79 (SD) pg/ml with the Tmax = 16.1 ± 4.2 (SD) min. J. Clin. Lab. Anal. 12:356–362, 1998. © 1998 Wiley‐Liss, Inc.