Peterson G M, McLean S, Aldous S, Von Witt R J, Millingen K S
Br J Clin Pharmacol. 1982 Aug;14(2):298-300. doi: 10.1111/j.1365-2125.1982.tb01981.x.
The plasma protein binding of phenytoin was investigated in 100 epileptic patients, using equilibrium dialysis at 37 degrees C. The unbound fractions of phenytoin in plasma formed a skewed distribution, with a range of 9.7 to 24.7% and a median value of 12.3%. Most (80%) patients appeared to form one group with free phenytoin fractions from 9.7 to 14.5%, while the remainder formed a group with elevated free fractions (greater than 14.5%). Total and unbound plasma concentrations of phenytoin were strongly correlated (r=0.95, P less than 0.0001). There was a weak correlation between increasing age and the unbound phenytoin fraction (r=0.28, P less than 0.01). The results indicate that measurement of the total phenytoin concentration in plasma should usually provide a reliable index of anticonvulsant effect. However, determination of the unbound phenytoin fraction would be beneficial in the management of those patients in whom this fraction may be elevated, due to interacting drugs or biochemical abnormalities.
采用37℃平衡透析法,对100例癫痫患者的苯妥英血浆蛋白结合情况进行了研究。苯妥英在血浆中的游离分数呈偏态分布,范围为9.7%至24.7%,中位数为12.3%。大多数(80%)患者似乎形成一组,游离苯妥英分数为9.7%至14.5%,而其余患者形成一组游离分数升高(大于14.5%)的组。苯妥英的总血浆浓度与游离血浆浓度密切相关(r=0.95,P<0.0001)。年龄增长与游离苯妥英分数之间存在弱相关性(r=0.28,P<0.01)。结果表明,测定血浆中苯妥英的总浓度通常应能提供抗惊厥作用的可靠指标。然而,对于那些由于相互作用药物或生化异常而可能导致该分数升高的患者,测定游离苯妥英分数将有助于治疗。