title: Effect of Chinese medicines Chan Su, Asian ginseng, Siberian ginseng, and American ginseng on a new digoxin immunoassay based on luminescent oxygen channeling technology.
abstract: BACKGROUND
  Chan Su, Asian ginseng, Siberian ginseng, and American ginseng are known to interfere with various digoxin immunoassays. Recently, a homogeneous sequential chemiluminescent assay for digoxin based on the luminescent oxygen channeling technology (LOCI digoxin) for application on the Dimension and Vista platform has been introduced into the market. The effects of interference by Chan Su and various ginsengs on this new immunoassay have not yet been reported.
  
  
  METHODS
  Aliquots of a drug-free serum pool were supplemented with Chan Su, Asian ginseng, Siberian ginseng, and American ginseng representing the expected in vivo concentrations after normal usage and cases of overdose. Serum digoxin concentrations were measured using the LOCI digoxin assay on the Vista 1500 analyzer. We also prepared 3 digoxin pools from patients receiving digoxin. Two digoxin pools were supplemented with these traditional medicines to investigate their effect on serum digoxin measurements. Mice were fed Chan Su extract to determine the potential of in vivo derived interfering factors. The possibility of eliminating interference of Chan Su on serum digoxin measurement was also investigated, by measuring free digoxin concentration after supplementing aliquots of the third digoxin pool with various amounts of Chan Su extract.
  
  
  RESULTS
  A clinically significant interference by Chan Su with serum digoxin measurement was observed using the LOCI digoxin assay. The various ginsengs demonstrated negligible effects. In addition, apparent digoxin concentrations were observed in sera of mice after feeding them with Chan Su; the half-life of digoxin-like immunoreactive components was approximately 1 hour. Moreover, serum digoxin concentrations were significantly elevated in the presence of Chan Su, whereas the various ginsengs exhibited no effect. Monitoring free digoxin can only partly eliminate the interference of Chan Su in serum digoxin measurement.
  
  
  CONCLUSIONS
  Chan Su interferes with serum digoxin measurement using the LOCI Digoxin, whereas the ginsengs demonstrated no measurable interference at clinically relevant concentrations.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Texas Medical School at Houston, 6431 Fannin, MSB 2.292, Houston, TX 77030, USA. amitava.dasgupta@uth.tmc.edu
authors.forename: Amitava
authors.initials: A
authors.lastname: Dasgupta
authors.forename: Erica
authors.initials: E
authors.lastname: Syklawer
authors.forename: Myrtle
authors.initials: M
authors.lastname: Johnson
authors.forename: Shen-An
authors.initials: SA
authors.lastname: Hwang
authors.forename: Sydney A
authors.initials: SA
authors.lastname: Boyd
authors.forename: Jeffrey K
authors.initials: JK
authors.lastname: Actor
mesh_terms: D000818:Animals; D002018:Bufanolides / Q000737:chemistry*; D004077:Digoxin / Q000097:blood*; D004305:Dose-Response Relationship, Drug; D004365:Drugs, Chinese Herbal; D028001:Eleutherococcus / Q000737:chemistry*; D006801:Humans; D007118:Immunoassay / Q000379:methods; D008163:Luminescent Measurements / Q000379:methods; D051379:Mice; D010100:Oxygen / Q000737:chemistry*; D005894:Panax / Q000737:chemistry*; D010936:Plant Extracts / Q000097:blood* / Q000737:chemistry
chemical_list: D002018:Bufanolides; D004365:Drugs, Chinese Herbal; D010936:Plant Extracts; C095591:chan su; D004077:Digoxin; D010100:Oxygen