A BIO-ASSAY TECHNIQUE FOR DETERMINATION OF TRYPANOCYDAL DRUG LEVELS, AND ITS APPLICATION IN ESTIMATING THE DURATION OF ACTIVITY OF BERENIL IN TREATED CATTLE

Publisher Summary This chapter discusses a bioassay technique for the determination of trypanocydal drug levels and its application in estimating the duration of activity of Berenil in treated cattle. By comparing the infectivity of trypanosomes after in vitro exposure to serum obtained from a cow before, and at intervals after, treatment with Berenil with the infectivity of trypanosomes exposed to serum containing known concentrations of Berenil, estimates can be made of drug levels in the cow serum subsequent to treatment. These results support the findings from other studies that Berenil is quickly excreted from treated animals. Information obtained from field observations, however, indicated that Berenil might persist at trypanocydal levels for much longer periods in treated cattle and led to devise methods to increase the sensitivity of the technique. The results show that sensitivity can be increased by in vitro exposure for longer periods, at higher temperatures. The exposure of organisms for periods in excess of 4 h, or at temperatures higher than 27°C, caused loss of infectivity in the control sample.