Micro high-performance liquid chromatographic determination of cardiac glycosides in beta-methyldigoxin and digoxin...

A micro high-performance liquid chromatographic (micro-HPLC) method has been developed for the assay of beta-methyldigoxin and digoxin tablets. Quantitation of cardiac glycosides in tablets was carried out by the incorporation of dexamethasone as an internal standard. The procedure consisted of disintegration of tablets, extraction with acetone-ethanol (9:1) and injection for micro-HPLC on an ODS micro column, using acetonitrile-water (28:72) for beta-methyldigoxin tablets and methanol-water (1:1) for digoxin tablets; the effluent was monitored by UV detection at 220 nm. The average values of the contents in beta-methyldigoxin and digoxin tablets were 99.6 and 100.2% of the labelled amounts, respectively. The proposed method is sufficiently precise and sensitive to examine the content uniformity of tablets.