Cardioactive steroid poisoning: a comparison of plant- and animal-derived compounds.
BACKGROUND
Cardioactive steroids (CASs) are found in plants, animals, and insects. Their affinity for Na+-K+ ATPase is attenuated by the type of lactone at carbon 17 (C17) of the steroid backbone: those with 5-membered lactone rings, or cardenolides, are derived mostly from plants with 6-membered rings or from animals with bufadienolides. A systematic review of CAS poisoning was performed to compare the mortality rate of cardenolides and bufadienolides.


METHODS
MEDLINE was searched for articles using commonly reported names of CASs, and keywords were limited to human cases only. We searched cases from 1982 to 2003, so that supportive care was similar and digoxin-specific Fab was available. Identified reports of CAS poisoning were read to exclude cases involving licensed pharmaceuticals. Inclusion criteria included hyperkalemia, gastrointestinal symptoms, electrocardiographic evidence of CAS toxicity, digoxin serum concentration, or history of exposure to a substance containing a CAS. Clinical data was collected, including information about treatment with digoxin-specific Fab and treatment outcome.


RESULTS
Fifty-nine articles, describing 924 patients, were identified. Eight hundred ninety-seven patients (97%) ingested a CAS with a 5-membered lactone ring, and mortality was 6% (n = 54). Twenty-seven patients (2.9%) ingested a CAS with a 6-membered lactone ring, and mortality was 29.6% (n = 8). The difference in mortality rates was statistically significant (p < 0.001, [X2]). CASs with 6-member rings accounted for the highest percentage of nonsuicidal exposures.


CONCLUSIONS
Although cardenolides accounted for the majority of exposures, bufadienolides were five times more lethal than cardenolides.
Barrueto
Fermin
F
Department of Emergency Medicine, University of Maryland School of Medicine and Department of Medicine, George Washington University, USA. fbarr001@umaryland.edu
Kirrane
Barbara M
BM
Cotter
Brian W
BW
Hoffman
Robert S
RS
Nelson
Lewis S
LS
D000818:Animals; D002018:Bufanolides / Q000737:chemistry / Q000506:poisoning*; D002298:Cardenolides / Q000737:chemistry / Q000506:poisoning*; D002316:Cardiotonic Agents / Q000737:chemistry / Q000506:poisoning*; D015394:Molecular Structure; D009026:Mortality / Q000639:trends; D028321:Plant Preparations / Q000737:chemistry / Q000506:poisoning*; D011041:Poisoning / Q000401:mortality / Q000628:therapy; D012107:Research Design
D002018:Bufanolides; D002298:Cardenolides; D002316:Cardiotonic Agents; D028321:Plant Preparations