Effect of Chinese Medicine Danshen and Indian Ayurvedic Medicine Bark of Arjuna Tree on a Relatively New LOCI Digoxin Assay for Application on the Vista 1500 Analyzer.

Background: Danshen is a traditional Chinese medicine and bark of Arjuna tree is an Ayurvedic medicine both indicated as heart tonic. Interference of Danshen in serum digoxin immunoassays has been reported but potential interference of extract of bark of Arjuna tree has not been reported. We studied potential interferences of Danshen and bark of Arjuna tree on a relatively new LOCI digoxin assay for application on the Vista 1500 analyzer (Siemens Diagnostics).

Methods: Aliquots of drug-free serum were supplemented with ethyl acetate extract of Danshen (two different brands studied) or aqueous or ethyl alcohol extract of bark of Arjuna tree and apparent digoxin concentrations were measured by the LOCI digoxin assay. In another experiment, aliquots of serum pool containing digoxin were further supplemented with Danshen or bark of Arjuna tree extract and digoxin concentrations were measured again using LOCI digoxin assay.

Results: Little apparent digoxin concentration was observed when aliquots of drug-free serum pools were supplemented with Danshen or bark of Arjuna tree extract. When aliquots of serum digoxin pool were further supplemented with these extract, we observed statistically significant negative interference but such differences may not be clinically significant.

Conclusion: We conclude that LOCI digoxin assay is virtually free from interferences of Danshen and extract of bark of Arjuna tree.