Isoniazid 為一抗結核藥，常與其他抗結核病藥物合併治療。臨床上常見的副作用包括有肝指數上升、周邊神經病變，嚴重副作用可能引起肝損傷、全身性紅斑狼瘡(systemic lupus erythematosus) 等。此外，有文獻報告指出isoniazid 亦可能導致嚴重的癲癇發作。本文探討一位診斷有肺結核的89 歲高齡女性，在開始服用isoniazid後的第40 天因出現急性譫妄及躁動症狀而住院，入院後進行腦波檢查發現雙側額葉有癲癇樣放電，給與levetiracetam 及pyridoxine 治療並暫停isoniazid 後狀況改善。一週後重新服用isoniazid 後癲癇再度發作，在排除低血鈉的疾病因素後，懷疑為isoniazid 引起的癲癇發作。藉由過去文獻回顧，導致癲癇發作原因可能與isoniazid干擾pyridoxine 代謝而使gamma-aminobutyric acid (GABA) 生成減少有關。此屬罕見的藥物不良反應，目前發生率尚未定義，藉此案例提醒醫護人員，病人服用isoniazid 治療期間應密切監測是否有精神狀態改變與癲癇相關的症狀出現。
 

Isoniazid is an antituberculosis drug, usually combined with other antituberculosis drugs for tuberculosis treatment. The common adverse effects of isoniazid are elevation of liver enzymes and peripheral neuropathy; serious adverse effects include liver injury and systemic lupus erythematosus. In addition, isoniazid has been reported to cause serious seizures. We describe a case of an 89-year-old female patient diagnosed with pulmonary tuberculosis who suffered from acute-onset delirium and agitation forty days after commencing isoniazid therapy. After admission, electroencephalography showed bilateral frontal epileptiform discharges; therefore, we administered levetiracetam and pyridoxine and withheld isoniazid for one week. The patient’s symptoms initially resolved, but they recurred after rechallenge with isoniazid. After ruling out hyponatremia, we highly suspected that the patient was experiencing isoniazid-induced seizures. According to the published literature, isoniazid is thought to cause seizures by interfering with the metabolism of pyridoxine, leading to a decrease in the synthesis of gamma-aminobutyric acid (GABA). This is a rare adverse drug reaction of isoniazid and its frequency has not been identified. We would like to remind healthcare workers to closely monitor all patients undergoing isoniazid therapy for signs of altered mental status and seizures.