Rapid detection of oleander poisoning by Dimension Vista digoxin assay (Flex Reagent Cartridge)

Oleander poisoning can be detected by digoxin immunoassays and for last two decades the fluorescence polarization immunoassay (FPIA) has been used for rapid detection of oleander poisoning in clinical laboratories. Recently, Abbott Laboratories (Abbott Park, IL) discontinued this assay. Therefore, we explored the possibility of using another digoxin assay (Dimension Vista Flex Reagent Cartridge, Tina Quant, EMIT 2000 and old FPIA assay for comparison) for rapid detection of oleander poisoning. When aliquots of drug-free serum pools were supplemented with pure oleandrin or oleander extract, we observed the highest apparent digoxin values using Dimension Vista digoxin assay (Flex Reagent Cartridge). We also observed significant apparent digoxin values in vivo in sera of mice both 1 and 2  hr after feeding with oleander extract. When a serum pool prepared from patients taking digoxin was further supplemented with various amounts of oleander extract, the highest falsely elevated digoxin values were observed with Dimension Vista digoxin assay. Monitoring free digoxin using Dimension Vista digoxin assay (Flex Reagent Cartridge) did not eliminate this interference. Digibind neutralized digoxin-like factors of oleander extract and such effect can be monitored by observing significant reduction in apparent free digoxin levels in the presence of Digibind as measured in the protein-free ultrafiltrate using Dimension Vista digoxin assay (Flex Reagent Cartridge).