Overdose : מינון יתר

4.9   Overdose

Symptoms
Cases of accidental and deliberate overdosage with oral therapy have been reported. At plasma concentrations of up to 5 to 6 times the maximum therapeutic levels, there are unlikely to be any symptoms other than nausea, vomiting and dizziness. Sign of acute massive overdose, i.e. plasma concentration 10 to 20 times the maximum therapeutic levels usually include CNS depression or coma with muscular hypotonia, hyporeflexia, miosis, impaired respiratory function, metabolic acidosis, hypotension and circulatory collapse/shock. A favourable outcome is usual.
However some deaths have occurred following massive overdose.

Symptoms may however be variable and seizures have been reported in the presence of very high plasma levels (see section 5.2). Cases of intracranial hypertension related to cerebral oedema have been reported.

The presence of sodium content in the Sodium Valproate Wockhardt formulations may lead to hypernatraemia when taken in overdose.

Management
Hospital management of overdose should be symptomatic, including cardio- respiratory- gastric monitoring. Gastric lavage may be useful up to 10-12 hours following ingestion. In case of valproate overdose resulting in hyperammonaemia, carnitine can be given through IV route to attempt to normalize ammonia levels. Naloxone has been successfully used in a few isolated cases, sometimes in association with activated charcoal given orally.

In case of massive overdose, Haemodialysis and haemoperfusion have been used successfully.