THE EVALUATION OF DIGITALIS PURPUREA A Comparison of Colorimetric and Chromatographie methods

Abstract

Three methods for the chemical evaluation of Digitalis have been investigated with particular reference to their relevance in the determination of biological potency of Digitalis. The colorimetric assay for total glycosides is an adequate criterion in quality control procedures but unsuitable for therapeutic aspects of evaluation. However, if the method is related to a biological potency, possibly obtained by simpler and less expensive methods than whole–animal infusion techniques, then such a ,potency ratio' may serve in the evaluation of the drug.

A colorimentric method is reported which enables the digitoxigenin glycosides to be determined. This method is more effective in quality control procedures than the simple total assay, particularly in the identification of chemical races of the species. However,, it offers little over the ,total' assay in assessing biological potency.

Chromatographie methods as instanced by the densitometric procedure of Linley (1973) offer real advantages in the assessment of biological potency, but await more detailed information on oral potency of the gitaloxigenin glycosides.