| Theme | Intoxication of Drugs and Poisons and Blood Purification Therapy (Case Report) | |
|---|---|---|
| Title | Phenytoin poisoning | |
| Publish Date | 2002/07 | |
| Author | Chiyo Kawasaki | Department of Pharmacy, Japanese Red Cross Kumamoto Hospital |
| Author | Souichi Uekihara | Department of Nephrology, Japanese Red Cross Kumamoto Hospital |
| Author | Shunichi Hayano | Department of Nephrology, Japanese Red Cross Kumamoto Hospital |
| Author | Reiko Nishi | Department of Pharmacy, Japanese Red Cross Kumamoto Hospital |
| [ Summary ] | The therapeutic range for phenytoin is narrow, 10 to 20 micro-g/ml. In patients with drug concentration at toxic range, specific features such as nystagmus, ataxia and drowsiness are observed and deaths have been reported. The time to peak plasma concentration (tmax) is prolonged since gastrointestinal absorption of phenytoin continues for a long time in overdosed cases. In addition, the elimination half-life (t1/2) is also prolonged due to saturation of liver metabolism, resulting in a consistantly high plasma concentration. Therefore, it is important to diagnose and select the appropriate clinical intervention based on these pharmacokinetic characteristics of phenytoin and the time of ingestion in overdosed cases. Although initiation of hemopurification has been considered in patients with severe intoxication symptoms, the effectiveness of hemodialysis in removing phenytoin is rather doubtful, due to the fact that the protein binding percentage of the drug is 90%. While there is a lack of consensus on the use of charcoal hemoperfusion in phenytoin overdose, we have successfully treated a phenytoin-overdosed patient with charcoal hemoperfusion. The utility of charcoal hemoperfusion in treating phenytoin overdosed patient has been proven clinically, with supporting data from in vitro experiments. |
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