[Cardioactive contaminants and actual active ingredient content of various digitalis preparations]

To establish possible cardioactive impurities which have not been totally separated while isolating the compound from plant material several preparations containing digoxin (NOVODIGAL = beta-acetyldigoxin, LANITOP = beta-methyldigoxin and LANICOR = digoxin) were analyzed by HPLC-chromatography after careful extraction. Impurities were found (digoxigenin, digoxigenin-monodigitoxosid, digoxigenin-bisdigitoxosid) which on the one hand occur as natural lanatosid-derivates in digitalis leaves but on the other hand also are described as possible metabolites of digoxin in human organism. The experiments have shown that the results of studies in metabolization of digoxin without knowledge of purity of the substance applied have to be interpreted with care.