Overdose : מינון יתר

4.9 Overdose

Emergency and lymphatic system disorders:
The possibility of multiple intoxication must always be considered, for example ingestion of more than one drug with suicidal intention.
a) Symptoms of overdose:
Acute intoxication is characterized by nausea, vomiting, hyperexcitability, tremor, ataxia, blurred vision, lethargy, depression, dysarthria, and cerebral seizures; malignant cardiac arrhythmia has been reported in one case.
Acute toxic psychoses in the form of states of confusion with visual hallucinations sometimes including coma and myoclonus have been observed after simultaneous administration of amantadine and other antiparkinsonian drugs.
b) Management of overdose:
There is no known specific drug treatment or antidote. In the event of life-threatening intoxication, intensive care is necessary additionally. Therapeutic measures to be considered include fluid intake and acidification of the urine for more rapid excretion of the substance, possibly sedation, anticonvulsive measures and antiarrhythmics (lidocaine i.v.).
For the treatment of neurotoxic symptoms (such as those described above), intravenous administration of physostigmine can be attempted at a dose of 1-2 mg every 2 hours in adults and 2  0.5 mg at intervals of 5-10 min up to a maximum dose of 2 mg in children.
Because of the low dialyzability of amantadine (approx. 5%), hemodialysis is not an option.
It is advisable to monitor patients particularly closely for possible QT prolongation and for factors that promote the occurrence of Torsades-de-Pointes, e.g. electrolyte imbalances (particularly hypokalemia and hypomagnesemia) and bradycardia.