A Study of Certain Factors Which Influence the Value of Digitalis as Estimated by the Cat Method of Assay of Hatcher and Magnus

Abstract

It is generally believed that the Hatcher's cat method as modified by Magnus for digitalis assay is rrost reliable because of the accuracy and constancy of its results. According. to many authors (1,2,3,4,5), the variation in the suscep tibility of, cats to digitalis was more pronounced than was described by Van Wi jngaarden (6). McFarlane and Masson (3) reported that there were probably two species of cats which differed in their resistance to digitalis. Recently experiments on the bioassay of digitalis by this cat method had been carried out at pharmacological laboratories in certain different districts of Japan, each using the same preparations.The results varied considerably and this study was undertaken to investigate those factors which may produce such discrepan. cies.The,.method devised includes many factors that may influence the results, far example family and species of the cats, sex, weight and the state, of nutri tion.. Many cats obstinately, refused to take food in the cage and this fasting state resulted in an emaciated animal. These animals were used to determine the effects of the state of nutrition on the value obtained by the assay. It , is felt, that the variability and/or the discrepancy of the results may be caused by any one or combination of these factors. MATERIALS AND METHODThe following factors are investigated to determine their influence on the 'results obtained . by the cat method for the biological assay of digitalis as describ ed by Hatcher and Magnus: