Development and evaluation of an enzyme-linked immunosorbent assay (ELISA)for the determination of the trypanocidal drug homidium in serum of treated cattle

Two enzyme-linked immunosorbent assays (ELISA) for the determination of hom idium in serum of treated cattle have been developed and evaluated. One is a direct competition (Assay 1) and the other an indirect competition assay (Assay 2). Both assays are highly sensitive with a limit of detection of 0. 1 ng homidium per mt serum. Homidium levels were measurable in serum of cat tle for over 2 months following administration of a single intramuscular (i .m.) dose at 1 mg/kg bodyweight. The level of sensitivity afforded by these assays makes them potentially useful tools in the pharmacokinetic evaluati on of homidium and for invetigating drug resistance or causes of drug failu re, Assay 2 was chosen as being most suitable for further studies.