A direct competitive ELISA for the simple, sensitive and accurate determination of diethylcarbamazine concentration in serum.

Improved methods for measurement of the anti-filariasis drug diethylcarbamazine in serum would assist in the design of effective therapy. The method evaluated in the present paper is a direct competitive ELISA which is sensitive, specific and accurate. Horseradish peroxidase-labelled diethylcarbamazine conjugate was incubated with diethylcarbamazine and anti-diethylcarbamazine antiserum over a bound second antibody. The enzyme activity of the remaining diethylcarbamazine-horseradish peroxidase conjugate was measured. The intra- and inter-assay coefficient of variation was < 10% in the range of 1.0-30 ng ml-1 and the limit of detection was 0.3 ng ml-1. The cross reactivities of anti-diethylcarbamazine antibodies with diethylcarbamazine metabolites and ivermectin were < 0.09%. Using the ELISA, the serum levels of diethylcarbamazine were successfully determined in mongolian jirds (Meriones unguiculantus) up to 4h following a single dose of 50 mg kg-1 of body weight. The values of pharmacokinetic parameters of diethylcarbamazine in jirds were determined.