Cardioactive steroid poisoning: a comparison of plant- and animal-derived compounds.

INTRODUCTION: 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. CONCLUSION: Although cardenolides accounted for the majority of exposures, bufadienolides were five times more lethal than cardenolides.

Acute pediatric digoxin ingestion.

Although most acute pediatric ingestions of digoxin or other related cardiac glycosides result in minimal or no symptoms, occasionally a child is symptomatic. Gastrointestinal complaints or first-degree AV block are the most common presenting symptoms. Children can generally be given a single dose of activated charcoal, observed, and discharged without any subsequent problems. However, some patients will be toxic and require monitoring, medication, and possibly digoxin-specific antibody fragments. The most important role of the clinician is to recognize the clinical manifestations and institute the appropriate therapy. As in the case presented, the history of an ingestion may not always be obtained initially. Thus, the physician should maintain a high index of suspicion for acute digoxin ingestion and order the appropriate confirmatory tests (eg, a digoxin level, a potassium level, and a 12-lead ECG) when necessary.