Overdose : מינון יתר

4.9 Overdose

Animal experience:
In rats and mice, significant lethality at oral doses of 1965 mg/kg and 2581 mg/kg, respectively, was observed.
Human experience:

Symptoms:

−   Fall of blood pressure ≤ 90 mmHg
−   Paleness
−   Sweating
−   Weak pulse
−   Tachycardia
−   Light-headedness on standing
−   Headache
−   Weakness
−   Dizziness
−   Nausea
−   Vomiting
−   Diarrhoea
Methaemoglobinaemia has been reported in patients receiving other organic nitrates.

During isosorbide mononitrate biotransformation nitrite ions are released, which may induce methaemoglobinaemia and cyanosis with subsequent tachypnoea, anxiety, loss of consciousness and cardiac arrest. It cannot be excluded that an overdose of isosorbide mononitrate may cause this adverse reaction.

In very high doses the intracranial pressure may be increased. This might lead to cerebral symptoms.

General procedure:
•   Stop intake of the drug
•   General procedures in the event of nitrate-related hypotension o Patients should be kept horizontal with the head lowered and legs raised o Supply oxygen o Expand plasma volume (i.v. fluids) o Specific treatment for shock (admit patient to intensive care unit) 
Special procedure:

•   Raising the blood pressure if the blood pressure is very low.
•   Treatment of methaemoglobinaemia o Reduction therapy of choice with vitamin C, methylene-blue or toluidine-blue o Administer oxygen (if necessary) o Initiate artificial ventilation o Hemodialysis (if necessary)
•   Resuscitation measures

In case of signs of respiratory and circulatory arrest, initiate resuscitation measures immediately.