Isopen-20 Overdosage

Symptoms of intoxication: The primary symptoms of intoxication are headache, a fall in blood pressure with orthostatic hypotension and reflex tachycardia.
High doses may cause methemoglobinemia with cyanosis, dyspnea and tachypnea, due to the formation of the nitrite ions.
Very high doses of Isosorbide-5-mononitrate may lead to increased intracranial pressure with cerebral symptoms.
Therapy of intoxication: Therapeutic measures should aim the normalization of blood pressure, which may be achieved in mild cases by keeping the patient recumbent in the shock position (put the patient in horizontal position with legs up and lower the head).
In the case of severe intoxication, the general guidelines for treatment of poisoning and shock should be followed.
Volume substitution may be necessary in the case of severe hypotension. Sympathomimetic drugs (e.g. norepinephrine, dopamine) may be used in exceptional cases.
Epinephrine is ineffective in reversing the severe hypotensive events associated with Isosorbide-5-mononitrate overdosage and should therefore not be used.
If methemoglobinemia is present, the following antidotes are recommended, depending on the severity of intoxication: Vitamin C, 1 g orally or I.V. as the sodium salt.
Methylene blue (I.V. only): up to 50 mL of a 1% methylene blue solution.
Toluidine blue (I.V. only): initially 2-4 mg/kg body weight, repeated hourly administrations of 2 mg/kg body weight, if necessary.
Oxygen should be administered, if necessary, as well as hemodialysis or exchange transfusion.