A two_dimensional HPLC method was developed for the determination of methotrexat ( MTX ) in human plasma. The samples were treated with trichloroacetate for sedimentation and high speed centrifugation, and the obtained supernatant was taken for analysis. The analytes in sample were separated on the first dimension column (ASTON C8 100 mm × 4. 6 mm, 5μm), and trapped on the middle column (ASTON SCX 20 mm × 4. 6 mm, 5 μm) using valve_switching technique for purification and storage. Finally, the trapped analytes were transferred to the second_dimension column (SAC C8 100 mm × 4. 6 mm, 5μm) for the second separation. The mobile phase used for the first dimension was 10 mmol/L ammonium acetate_acetonitrile(9∶1, V/V, pH=3. 8) with a flow rate of 1 mL/min and the mobile phase used for middle column was 10 mmol/L phosphoric acid ( pH=3 . 0 ) . The mobile phase used in second_dimension was a mixed solution of 50 mmol/L ammonium acetate and acetonitrile (87∶10, V/V, pH=5. 2). UV detection was carried out at 306 nm and completed in 4 min. The calibration curve showed a linearity range from 0. 0879 to 5. 154 μmol/L (r=0. 99998). The LOQ was 0. 005 μmol/L. The intra_and inter_day precisions were lower than 1. 5% and 1. 8%, respectively. The relative recovery and the absolute recovery were 99. 1% - 101. 2% and 85. 67%-86. 35%, respectively. The assay is simple, accurate, reproducible, and suitable for the therapeutic drug monitoring of MTX in the hospital and the study on the pharmacokinetics of MTX.

OBJECTIVE: To investigate whether single nucleotide polymorphisms (SNPs) of rs2298771 and rs3812718 of the sodium channel α-subunit type 1 (SCN1A) gene affect the efficacy of carbamazepine (CBZ) treatment for seizures in Chinese Han epileptic patients. METHODS: SNP rs2298771 and rs3812718 of the SCN1A gene from 628 patients were genotyped. CBZ monotherapy was administered to the subjects with new-onset partial seizures. The efficacy was defined as the decrease in the number of seizures. Four semi-quantitative levels were used to assess the efficacy: seizure-free (SF), >75% seizure decrease (SD), 50%-75% SD, and <50% SD in the number of seizures compared with patients' initial conditions. RESULTS: After the 12 month treatment with CBZ monotherapy, the rate of SF patients with G allele of the SNP rs2298771 was significantly lower than that in patients with the AA genotype (P=0.003). The heterozygote and homozygote of the G allele at SNP rs2298771 predicted the low SF rate (OR=2.101, 95% CI 1.289-3.425). Marginal significance was observed between the dichotomous efficacy of SF and non-SF in 3 partial seizure types (P=0.028). CONCLUSION rs2298771 is significantly associated with the efficacy of CBZ monotherapy in Chinese Han epileptic patients.
Alleles ; Asian Continental Ancestry Group ; Carbamazepine ; therapeutic use ; Epilepsy ; Genotype ; Humans ; NAV1.1 Voltage-Gated Sodium Channel ; genetics ; Polymorphism, Single Nucleotide ; Seizures ; drug therapy ; genetics