Abstract: Background　Difenidol hydrochloride is an over-the-counter drug often used to treat dizziness induced by various reasons. There have been recent case reports regarding acute difenidol poisoning due to overdose，but the patients'clinical characteristics according to plasma concentration level have not been summarized. Objective　To report the clinical characteristics and treatment of 9 cases of difenidol poisoning due to overdose with a focus on the value of monitoring plasma concentration in the diagnosis and treatment. Methods　We retrospectively studied a total of 9 patients of acute difenidol poisoning due to overdose admitted by Emergency Department，Peking University Third Hospital from June 2019 to May 2020. We summarized the clinical manifestations，plasma concentration，treatment history and prognosis of the patients. Results　There were 7 female patients and 2 male patients with an average age of（20.7±1.9）years. The average dose was（2 700±1 478）mg. The duration from oral medication to consultation was 3.5（6.5） hours. And the median plasma concentration was 3.15（26.27） mg/L. Severe poisoning was seen in two patients，one of them died，with the maximum plasma concentration of difenidol ≥35 mg/L，and clinical manifestations including coma〔Glasgow Coma Scale score（GCS）equals 3〕，seizure，respiratory failure，persistent hypotension and cardiac arrest. Four patients with maximum plasma concentration ≤2.5 mg/L demonstrated relatively mild clinical manifestations，such as dizziness，nausea，vomiting，fatigue，limb tremor，etc. The first hemoperfusion produced a decrease of about（47.51±22.16）% in difenidol plasma concentration. Eight out of 9 patients were discharged from hospital after recovery. The survival rate was 88.9%. The average hospitalization days were（4.7±3.3）d. Conclusion　Though the relationship of oral dose and maximum plasma concentration was not able to be clarified in patients with overdose difenidol induced poisoning，monitoring the plasma concentration may be beneficial to assessing the severity and prognosis. Caution is suggested against the cardiac arrest risk in patients with coma，respiratory failure and persistent hypotension. Hemoperfusion could effectively reduce the plasma concentration of difenidol hydrochloride.

Key words: Difenidol hydrochloride, Poisoning, Plasma concentration, Renal dialysis, Hemoperfusion

摘要： 背景　盐酸地芬尼多是用于治疗各种原因所致眩晕的非处方药物。近年来因过量服用盐酸地芬尼多急性中毒的个案时有报道，但至今尚无基于急性中毒患者血药浓度的临床特征报道。目的　通过总结9例因过量服用盐酸地芬尼多中毒患者的临床特征及诊疗结果，分析血药浓度检测在因过量服用盐酸地芬尼多急性中毒患者诊治过程中的价值。方法　本文回顾性分析了2019年6月—2020年5月因过量服用盐酸地芬尼多急性中毒就诊于北京大学第三医院急诊科的9例患者的临床表现、血药浓度、治疗经过及预后。结果　9例盐酸地芬尼多急性中毒患者中女7例，男2例；平均年龄（20.7±1.9）岁；平均服药剂量（2 700±1 478）mg；中位服药至就诊间隔时间为3.5（6.5）h；血药浓度为3.15（26.27）mg/L。2例盐酸地芬尼多最高血药浓度≥35 mg/L的患者出现昏迷〔格拉斯哥昏迷量表（GCS）评分为3分〕、抽搐、呼吸衰竭、持续性低血压及心脏骤停的严重中毒表现，其中1例死亡。4例最高血药浓度≤2.5 mg/L的患者中毒表现相对较轻，主要为头晕、恶心呕吐、肢体乏力、肢体震颤等症状。首次血液灌流治疗前后动态监测盐酸地芬尼多血药浓度下降（47.51±22.16）%。出院时8例存活，存活率为88.9%，平均住院天数为（4.7±3.3）d。结论　在盐酸地芬尼多中毒患者的诊治中，服药剂量与最高血药浓度的关系不明确，监测血药浓度可能有利于对疾病严重程度及预后的评估。当患者出现昏迷、持续性低血压和呼吸衰竭时要警惕心脏骤停的风险，血液灌流可有效降低盐酸地芬尼多血药浓度。

关键词: 盐酸地芬尼多, 中毒, 血药浓度, 肾透析, 血液灌流