Isordil Overdosage

Symptoms of nitrate overdosage may include the following: a prompt fall in blood pressure, persistent and throbbing headache, vertigo, palpitation, visual disturbances, flushed and perspiring skin (later becoming cold and cyanotic), nausea, and vomiting (possibly with colic and even bloody diarrhea), syncope (especially in the upright position), methemoglobinemia with cyanosis and anoxia, initial hyperpnea, dyspnea and slow breathing, slow pulse (dicrotic and intermittent), heart block, increased intracranial pressure with cerebral symptoms of confusion and moderate fever, paralysis and coma followed by clonic convulsions and possibly death due to circulatory collapse.
It is not known what dose of the drug is associated with symptoms of overdosing or what dose of the drug would be life-threatening. The acute oral LD₅₀ of isosorbide dinitrate in rats was found to be approximately 1100 mg/kg of body weight. These animal experiments indicate that approximately 500 times the usual therapeutic dose would be required to produce such toxic symptoms in humans. It is not known whether the drug is dialyzable.
Suggested treatment of overdosage: Prompt removal of the ingested material by gastric lavage, if ingestion was recent and the patient is conscious. Keep the patient recumbent in a shock position and comfortably warm. Passive movements of the extremities may aid venous return. Administer oxygen and artificial respiration if necessary. If methemoglobinemia is present, administer methylene blue (1% solution), 1 to 2 mg/kg intravenously. Epinephrine is ineffective in reversing the severe hypotensive events associated with overdose. Epinephrine and related compounds are contraindicated in this situation.