Phenytoin overdosage

Several methods have been proposed to enhance the elimination of phenytoin after overdose, and the effectiveness of hemo-perfusion is debated. A woman with severe iatrogenic phenytoin overdosage, with a peak plasma concentration of 117 mg/1 (29 pmol/l) benefited substantially from three sessions of a 4-hour long combination of activated charcoal hemoperfusion and high-flux hemodialysis these procedures considerably shortened the half-life of phenytoin from 40-100 hours to 7-13 hours [260 ]. 

Phenytoin is an anti-epileptic drug. Patients taking anti-epileptic drugs are advised to take the medicine routinely, as directed, to stabilise and to avoid epileptic attacks as much as possible. Phenytoin has a narrow therapeutic index so it is important to identify side-effects. It may cause blood disorders. Patients are therefore advised to report immediately any symptoms of bruising or unexplained bleeding. Visual symptoms as a result of phenytoin do not commonly occur. Their occurrence may indicate overdosage. 

Acute adverse effects seen after phenytoin administration usually result from overdosage. They are generally characterized by nystagmus, ataxia, vertigo, and diplopia (cerebellovestibular dysfunction). Higher doses lead to altered levels of consciousness and cognitive changes. 

Overdosage toxidty Poisoning with antipsychotics other than thioridazine is not usually fatal. Hypotension often responds to fluid replacement. Neuroleptics lower the convulsive threshold and may cause seizures, which are usually managed with diazepam or phenytoin. Thioridazine overdose, because of cardiotoxicity, is more difficult to treat. 

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