Isradipine overdose
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Minimal empirical data are available on Isradipine overdosage. Three individual suicide attempts with dosages of Isradipine reported to be from 20 mg up to 100 mg resulted in lethargy, sinus tachycardia and, in the case of the person ingesting 100 mg, transient hypotension which responded to fluid therapy. A foreign report of the ingestion of 200 mg of Isradipine with ethanol resulted only in flushing, tachycardia with ST depression on ECG, and hypotension, all of which were reversible. The ingestion of 5 mg of Isradipine by a 22-month old child and the accidental ingestion of 100 mg of Isradipine by a 58-year old female did not result in any sequelae.
Available data suggest that, as with other dihydropyridines, overdosage with Isradipine might result in excessive peripheral vasodilatation with subsequent marked and probably prolonged systemic hypotension, and tachycardia. Emesis, gastric lavage, administration of activated charcoal followed in 30 minutes by a saline cathartic would be reasonable therapy.
Isradipine is highly protein-bound and not removed by hemodialysis. Overdosage characterized by clinically significant hypotension should be treated with active cardiovascular support including monitoring of cardiac and respiratory function, elevation of lower extremities, and attention to circulating fluid volume and urine output. A vasoconstrictor (such as epinephrine, norepinephrine, or levarterenol) may be helpful in restoring a normotensive state, provided that there is no contraindication to its use.
Refractory hypotension or AV conduction disturbances may be treated with intravenous calcium salts, or glucagon. Cimetidine should be withheld in such instances due to the risk of further increasing plasma Isradipine levels.
Significant lethality was observed in mice given oral doses of over 200 mg/kg and rabbits given about 50 mg/kg of Isradipine. Rats tolerated doses of over 2000 mg/kg without effects on survival.
Adapted from the FDA Package Insert.