Question of the Day – Wednesday March 25, 2020

Several herbal medications are reported to interfere with digoxin immunoassays. What herbals have been reported to do this? What is negative interference?

Chan su is derived from the skin and auricular glands of several Chinese toads and contains several cardioactive bufadienolides that cross react with digoxin with some of the various digoxin immunoassays. Siberian ginseng has also been reported to give a false positive digoxin measurement in a single case report. The validity of this single report has been questioned. Dan shen, an extract of Salvia miltiorrhiza (Chinese sage), contains tanshinones structurally similar to digoxin and may result in a false positive digoxin measurement. Depending on the specific assay used the presence and degree of interference varies. Negative interference is a false lowering of the measured concentration of a drug due to the presence of another substance. Dan Shen may cause a false lowering in the measured digoxin concentration in someone using both digoxin and Dan shen.  (Dasgupta A. Endogenous and Exogenous Digoxin-like Immunoreactive Substances Impact on Therapeutic Drug Monitoring of Digoxin. Am J Clin Pathol 2002;118:132-140 Dasgupta A, Sengupta TK, Johnson M. 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. J Clin Lab Anal. 2015;29:263-7)\

Submitted by Michael Hodgman MD on behalf of the Herbal and Dietary Supplements Section