Differences between the Measured and Calculated Free Serum Phenytoin Concentrations in Epileptic Patients
Differences between the Measured and Calculated Free Serum Phenytoin Concentrations in Epileptic Patients
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DOI：
10.3349/ymj.2009.50.4.517
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发表时间：
2009-08-31
影响因子：
2.4
通讯作者：
Kim, Won-Joo
中科院分区：
文献类型：
--
作者：
Hong, Ji-Man;Choi, Young-Chul;Kim, Won-Joo
目的：苯妥英的药代动力学因遗传和环境差异而变得复杂。因此，监测接受苯妥英钠治疗的患者的血药浓度非常重要。由于血清中苯妥英钠的大部分是与蛋白质结合的，因此血清白蛋白水平会影响苯妥英钠的游离量。材料和方法：我们用Sheiner-Tozer方程比较了服用苯妥英单药的癫痫患者测得的和计算出的苯妥英水平。本研究共纳入49例患者(男30例，女19例；年龄15-87岁)，分析其低谷血清苯妥英钠和白蛋白浓度。结果：苯妥英钠的游离浓度与总浓度呈中度线性相关(r=0.822，p<；0.001)。游离苯妥英钠的测定值与计算值相差很大(0.65+/-0.88微克/毫升；95%可信区间-1.11~2.41)。将患者按白蛋白浓度分组后，低蛋白血症患者(<3.5g/dL)比正常蛋白血症组(<3.5g/dL)有更大的百分比差异(<2.5g/dL)。结论：在低白蛋白血症患者中，测定游离苯妥英钠浓度是正确评价苯妥英钠浓度的必要手段，而不是由总苯妥英钠浓度计算出来的。
Purpose: The pharmacokinetics of phenytoin is complicated by genetic and environmental differences. It is, therefore, important to monitor the serum concentrations in patients who receive phenytoin. Because most of the phenytoin in serum is bound to proteins, the level of serum albumin influences the amount of free phenytoin. Materials and Methods: We compared the measured and calculated free phenytoin levels in epileptic patients who were taking phenytoin monotherapy, using the Sheiner-Tozer equation. A total of 49 patients (30 men and 19 women; age range, 15 - 87 years) were included in the study and their trough serum phenytoin and albumin concentrations were analyzed. Results: The linear correlation between free and total phenytoin concentrations was moderate (r = 0.822, p < 0.001). The mean difference between measured and calculated free phenytoin was large (0.65 +/- 0.88 mu g/mL; 95% confidence interval (CI), -1.11 to 2.41). After dividing the patients into groups by albumin concentration, hypoalbuminemic patients (< 3.5 g/dL) more often had a greater percent difference (>= 20%) than observed in the normoalbuminemic (>= 3.5 g/dL) group. Conclusion: In hypoalbuminemic patients, the measurement of free phenytoin level is necessary to properly evaluate the phenytoin level than that calculated from total phenytoin level.