sodium-dodecyl-sulfate and Epilepsy

Phenytoin is a widely used anti-seizure agent, and a good correlation is observed between its concentration in plasma and the clinical effect. We developed a selective CE with UV detection at 200 nm for analysis of free and total levels of phenytoin in human plasma based on MEKC. A sample pretreatment by liquid-liquid extraction with ethyl acetate for determination of total level of phenytoin and serum ultrafiltrate was prepared by ultrafiltration technique (ultrafiltration membrane 30 kDa; 2000 g, 10 min) for determination of free level of phenytoin and subsequent quantification by MEKC was used. MEKC was performed in Tris buffer (25 mM; pH 10.5) containing SDS (180 mM) and EG (13%) as BGE. Hydrodynamic injection for phenytoin determination (0.5 psi 5 s for total level, 2 psi 5 s for free level) was used to introduce samples. The separation voltage was set at 20 kV. Data obtained by MEKC were compared with the results by a validated HPLC method. The MEKC assay of phenytoin exhibited a very good correlation with respect to HPLC by Bland-Altman method. The equations for the Passing-Bablok regression line were as follows: for total level: MEKC=1.0143 x HPLC+0.0976, r(2)=1; for free level: MEKC=1.0013 x HPLC-0.0016, r(2)=1. The proposed method was applied successfully to monitor free and total levels of phentoin in 20 patients with seizures.

Topics: Adult; Calibration; Chromatography, High Pressure Liquid; Chromatography, Micellar Electrokinetic Capillary; Electrophoresis, Capillary; Epilepsy; Humans; Hydrogen-Ion Concentration; Linear Models; Phenytoin; Reproducibility of Results; Sensitivity and Specificity; Sodium Dodecyl Sulfate; Tromethamine; Young Adult

To develop a rapid and feasible method based on micellar electrokinetic capillary chromatography (MECC) for the simultaneous determination of antiepileptic drugs (AEDs)--phenytoin (PHT), phenobarbital (PB), carbamazepine (CBZ), primidone (PRM) and clonazepam (CZP) in human plasma.. Several factors that impact the separation of AEDs with MECC were investigated, such as concentration of sodium dodecyl sulfate (SDS), buffer compositions, pH, organic modifier, internal diameter and temperature, and an optimized MECC running condition was obtained the running buffer consisted of 8 mmol x L(-1) phosphate, 3 mmol x L(-1) sodium tetraborate, and 50 mmol x L(-1) sodium dodecylsulfate (SDS) (pH 8.0), containing acetonitrile (ACN) (18%) as organic modifier. Detection at 210 nm, run at 25 kV at 30 degrees C in a untreated fused silica capillary (50/45.5 cm length, 50 microm ID).. The reproducibility of both migration time and relative peak area with MECC analysis were appropriate for the intra- and inter-assay coefficients. The evaluated drugs concentration intervals of PRM 1.0-40.0 microg x mL(-1), PB 1.0-60.0 microg x mL(-1), PHT 1.0-40.0 microg x mL(-1), CBZ 1.0-40.0 microg x mL(-1), CZP 0.2-8.0 microg x mL(-1) were linear with correlation coefficients higher than 0.999 1, and coefficients of the variation of the points of the calibration curve lower than 10%. The recoveries of AEDs varied from 80.0% to 100.0%, depending on the drug, with coefficients of the variation lower than 10.0%.. The MECC technique is showed to be rapid, simple, efficient and low cost when applied to monitoring therapeutic drugs in patient treated with a combination of PHT and other AEDs such as hepatic enzyme-inducing agents.

Topics: Anticonvulsants; Buffers; Carbamazepine; Chromatography, Micellar Electrokinetic Capillary; Clonazepam; Epilepsy; Humans; Hydrogen-Ion Concentration; Phenobarbital; Phenytoin; Primidone; Sensitivity and Specificity; Sodium Dodecyl Sulfate