HPLC测定氯唑沙宗片的含量和有关物质

目的 测定氯唑沙宗片的含量和有关物质.方法 采用HPLC法,用DiamonsilTM C18(250 mm×4.6 mm,5 μm)色谱柱;流动相为0.05 mol·L-1枸橼酸缓冲液(三乙胺调pH3.5)-乙腈(60:40);流速1.0 ml·min-1;检测波长280 nm;柱温30℃;进样量20μl.结果 氯唑沙宗与其相邻杂质峰能完全分离;在24.84～496.70 μg·ml-1范围内线性关系良好(r2=0.9998).结论 所建方法简便、准确、专属性好,可用于氯唑沙宗及其制剂的含量测定和有关物质的检查.     

HPLC法同时测定大鼠血浆中氯唑沙宗和咪达唑仑的浓度

目的:建立同时测定大鼠血浆中CYP450探针药物氯唑沙宗(CYP2E1)和咪达唑仑(CYP3A4)浓度的高效液相色谱法.方法:色谱柱为Incrtsil-C18(250 mm×4.6 mm,5μm);流动相为乙腈-20 mmol· L·1乙酸铵-乙酸(45∶55∶0.1,v/v);流速为1mL·min-1;紫外检测波长(λ)为210nm;柱温为40℃.结果:氯唑沙宗和咪达唑仑均在0.05～30 μg· mL-1的范围内线性关系良好,最低检测限均为0.05μg· mL-1,低、中、高三个浓度的回收率分别为96.47％±4.35％、112.56％+4.05％、112.64％±4.28％;85.68％±2.81％、93.53％+3,70％、110.67％+5.54％.结论:本方法操作简便,灵敏度高,快速可靠,可同时用于血浆中CYP450亚型酶的探针药物氯唑沙宗和咪达唑仑的浓度的测定.     

海王生物挑战洋疫苗霸主地位

目的测定氯唑沙宗片中氯唑沙宗含量。方法采用毛细管气相色谱法,色谱柱:OV-1弹性石英毛细管柱30mm×0.25mm×0.1μm,以咖啡因为内标物,汽化室温度:220℃,检测器温度:250℃;检测器:FID检测器;载气;氮气;流速:2.5ml·min-1,尾吹:40ml·min-1,分流比5:1。结果氯唑沙宗15-40μg·ml-1(r=0.9996)范围内呈良好线性关系,平均回收率为100.6%。结论该方法测定氟唑沙宗含量准确、可靠,回收率高。     

毛细管气相色谱法测定氯唑沙宗片含量

目的　测定氯唑沙宗片中氯唑沙宗含量。方法　采用毛细管气相色谱法,色谱柱:OV -I弹性石英毛细管柱(30m×0 . 2 5mm,0 . 1μm),汽化室温度:2 2 0℃,检测器温度:2 5 0℃;检测器:FID检测器;载气:氮气;流速:2 . 5ml·min-1,尾吹:2 0ml·min-1,分流比5∶1。结果　氯唑沙宗15～4 0 μg·ml-1(r =0 9998)范围内呈良好线性关系,平均回收率为10 0 . 2 %。结论　该方法测定氯唑沙宗含量准确、可靠,回收率高。     

Effect of piperine on CYP2E1 enzyme activity of chlorzoxazone in healthy volunteers

1.?The purpose of the present study was to investigate the effect of piperine (PIP) on CYP2E1 enzyme activity and pharmacokinetics of chlorzoxazone (CHZ) in healthy volunteers.

2.?An open-label, two period, sequential study was conducted in 12 healthy volunteers. A single dose of PIP 20?mg was administered daily for 10 days during treatment phase. A single dose of CHZ 250?mg was administered during control and after treatment phases under fasting conditions. The blood samples were collected at predetermined time intervals after CHZ dosing and analyzed by HPLC.

3.?Treatment with PIP significantly enhanced maximum plasma concentration (C_max) (3.14–4.96?μg/mL)_, area under the curve (AUC) (10.46–17.78?μg h/mL), half life (T_1/2) (1.26–1.82?h) and significantly decreased elimination rate constant (K_el) (0.57–0.41?h?^??¹), apparent oral clearance (CL/F) (24.76–13.65?L/h) of CHZ when compared to control. In addition, treatment with PIP significantly decreased C_max (0.22–0.15?μg/mL), AUC (0.94–0.68?μg h/mL), T_1/2 (2.54–1.68?h) and significantly increased K_el (0.32–0.43?h?^??¹) of 6-hydroxychlorzoxazone (6-OHCHZ) as compared to control. Furthermore, treatment with PIP significantly decreased metabolite to parent (6-OHCHZ/CHZ) ratios of C_max, AUC, T_1/2 and significantly increased K_el ratio of 6-OHCHZ/CHZ, which indicate the decreased formation of CHZ to 6-OHCHZ.

4.?The results suggest that altered pharmacokinetics of CHZ might be attributed to PIP mediated inhibition of CYP2E1 enzyme, which indicate significant pharmacokinetic interaction present between PIP and CHZ. The inhibition of CYP2E1 by PIP may represent a novel therapeutic benefit for minimizing ethanol induced CYP2E1 enzyme activity and results in reduced hepatotoxicity of ethanol.     

反相高效液相法测定氯唑沙宗片含量及溶出度

目的建立氯唑沙宗片含量和溶出度测定方法。方法采用C18(4.6mm×15cm)色谱柱,流动相为甲醇-水(60:40),检测波长为280nm,柱温40℃,流速为1.0mL/min,进样量为20μL。结果在2～40μg/mL范围内氯唑沙宗浓度与峰面积之间有良好的线性关系,平均回收率为100.2%。结论该方法简便准确,重现性好,在此色谱条件下,应用反相高效液相色谱法对氯唑沙宗进行测定无干扰,因此,此方法可用于测定氯唑沙宗片的含量和溶出度。     

氯唑沙宗对离体大鼠胸主动脉的抗收缩作用

目的研究氯唑沙宗(Chlorzoxazone,CZ)对离体大鼠胸主动脉的抗收缩作用。方法采用大鼠离体胸主动脉环灌流法,测定血管环张力的变化。实验观察:1)动脉环在KH液中稳定1h后,向浴槽内加入25mMKCl预收缩血管,5min后给予300μM氯唑沙宗,观察其对血管的作用,对内皮去除的血管重复上述步骤。2)动脉环处于平衡状态时先加入不同浓度氯唑沙宗(100,300,500μM),5分钟后给予25mMKCl,观察血管的收缩情况。3)无钙液反复冲洗动脉环,待血管稳定后,给予200μM氯唑沙宗或2μM维拉帕米,10分钟后加入含CaCl2(0.1~2mM)的高钾液,观察血管的张力变化。结果1)对KCl预收缩的内皮完整或去内皮的大鼠胸主动脉,氯唑沙宗均有舒张作用。2)氯唑沙宗剂量依赖性地对抗KCl诱导的收缩作用(P<0.05)。3)在无钙高钾液中,氯唑沙宗明显降低CaCl2所引起的胸主动脉环的收缩。结论氯唑沙宗非内皮依赖性的舒张大鼠离体胸主动脉。     

Variability in the disposition of chlorzoxazone

Chlorzoxazone is 6-hydroxylated by cytochrome P450 2E1 (CYP 2E1), which bioactivates many toxic and carcinogenic molecules. Seventeen volunteers of varying age, ethnicity, and gender received a 250 mg tablet of chlorzoxazone and their blood and urine were sampled frequently for 8 h. V/F = 42 ± 21 L and CL/F = 412 ± 120 mL min^?1. Comparison of these values with a study by other investigators using a suspension dosage form suggested that relative F_tablet ± 0.7. The fraction excreted in the urine as 6-hydroxychlorzoxazone (f_2,6-OH) was 0.39 ± 0.20 and that portion of the total CL accounted for by CYP 2E1-mediated metabolism (CL_6-OH) was 163 ± 95 mL min^?1. Thus, while V/F and CL/F varied by factors of less than five, f_e,6-OH varied 16-fold and CL_6-OH varied 28-fold. These results suggested that there was considerable inter-individual variability in the metabolism of chlorzoxazone to 6-hydroxychlorzoxazone. This variability will significantly affect the construction of physiologically based pharmacokinetic models that use the 6-hydroxylation of chlorzoxazone as a marker for an individual's CYP 2E1 phenotype.     

Comparison of chlorzoxazone one-sample methods to estimate CYP2E1 activity in humans

Objective Comparison of a one-sample with a multi-sample method (the metabolic fractional clearance) to estimate CYP2E1 activity in humans.Methods Healthy, male Caucasians (n=19) were included. The multi-sample fractional clearance (Cl_fe) of chlorzoxazone was compared with one-time-point clearance estimation (Cl_est) at 3, 4, 5 and 6 h. Furthermore, the metabolite/drug ratios (MRs) estimated from one-time-point samples at 1, 2, 3, 4, 5 and 6 h were compared with Cl_fe.Results The concordance between Cl_est and Cl_fe was highest at 6 h. The minimal mean prediction error (MPE) of Cl_est as a percentage of actual mean Cl_fe was –4.2% at 6 h. Furthermore, regarding Cl_fe, there was a negligible difference (P=0.56) of bias between Cl_est at 3 h (MPE=–8.9%) and 6 h (MPE=–4.2%). The best concordance between MR and Cl_fe was found at 3 h (r=0.74; P<0.001).Conclusion All three single-dose-sample estimates, Cl_est at 3 h or 6 h, and MR at 3 h, can serve as reliable markers of CYP2E1 activity. The one-sample clearance method is an accurate, renal function-independent measure of the intrinsic activity; it is simple to use and easily applicable to humans.