Abstract

After suitable fractionation, the digitoxin in samples of Digitalis purpurea tincture has been estimated by a fluorometric procedure. Among five preparations so studied, the estimated digitoxin agreed well with the oral potency in man determined by Dr. Harry Gold. The chemical values varied between 10 and 19 per cent of the intravenous lethal equivalent in cat or pigeon. Because the digitoxin content of powdered digitalis leaf is not constant, the intravenous lethal dose in animals is a poor index of its oral potency in man.