| 特集名 | 薬物・毒物中毒と血液浄化法(症例集) | |
|---|---|---|
| 題名 | [中毒症例]III. 医薬品 (9) フェニトイン(抗てんかん薬) | |
| 発刊年月 | 2002年 07月 | |
| 著者 | 川崎 知世 | 熊本赤十字病院薬剤部(現 慶應義塾大学病院治験管理センター) |
| 著者 | 上木原 宗一 | 熊本赤十字病院腎センター |
| 著者 | 早野 俊一 | 熊本赤十字病院腎センター |
| 著者 | 西 玲子 | 熊本赤十字病院薬剤部 |
| 【 要旨 】 | フェニトインの有効域は10～20micro-g/mlと狭く，中毒域においては眼振や運動失調，傾眠状態などの症状が出現し，死亡例も報告されている．フェニトインの過量服用時には，消化管からの吸収が長時間続くことによる最高血中濃度到達時間(tmax)の延長に加え，肝臓での代謝速度の飽和により高血中濃度が持続して消失半減期(t1/2)が延長する．したがって，これらの体内動態学的特徴と服用時間をもとに，診断ならびに治療法の選択を行っていくことが重要である． 重症例では血液浄化法も考慮するが，フェニトインの蛋白結合率は90％であるため，血液透析法による効果はあまり期待できない．一方，フェニトイン中毒時の血液吸着法による有効性に関しては明確な評価がなされていなかったが，われわれは血液吸着法が奏効を示したフェニトイン中毒症例を経験し，その有用性を明らかにした． |
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| Theme | Intoxication of Drugs and Poisons and Blood Purification Therapy (Case Report) | |
|---|---|---|
| Title | Phenytoin poisoning | |
| 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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