Overdose : מינון יתר

4.9   Overdose

Symptoms
An overdose with vincristine leads to the occurrence of the above mentioned undesirable effects, in an intensified manner. In children younger than 13 years of age, overdose of 10 times the recommended dose has had fatal results. In this patient group, severe symptoms can occur with doses of 3-4 mg/m2. Adults can expect severe symptoms after the administration of single doses of 3 mg/m2 or more.
The main clinical symptoms of overdose are abdominal pain, neurotoxic effects such as areflexia, sensory and motor disturbances, somnolence, thrombocytopenia, leukopenia, and paralytic ileus.

Management
There is no known antidote to vincristine sulfate. Treatment is symptomatic and supportive. On appearance of an overdose, careful monitoring of the patient is required. The following measures should be considered.
• The serum electrolyte concentrations and fluid balance should be carefully monitored and when signs of inappropriate ADH secretion occur, fluid restriction must be initiated • Administration of an anti-convulsive agent for at least 1 week after overdose • Monitoring of the cardiovascular system
• Monitoring of the blood, after which action should be based on the observed bone marrow depression
• Use of enemas to prevent ileus
• Folinate may be used. A proposed schedule is 100 mg intravenously every 3 hours for 24 hours followed by every 6 hours for at least 48 hours.
Because only very small quantities of the medicinal product end up in dialysis, haemodialysis in case of overdose is probably not effective.