Profiling of levoamphetamine and related substances in dexamphetamine sulfate by capillary electrophoresis

A capillary electrophoresis method for the simultaneous determination of the enantiomeric purity of dexamphetamine as well as the analysis of 1R,2S-(−)-norephedrine and 1S,2S-(+)-norpseudoephedrine as potential impurities has been developed and validated. Heptakis-(2,3-di-O-acetyl-6-O-sulfo)-β-cyclodextrin was chosen as chiral selector upon a screening of neutral and charged cyclodextrin derivatives. Separation of the analytes was achieved in a fused-silica capillary at 20 °C using an applied voltage of 25 kV. The optimized background electrolyte consisted of a 0.1 M sodium phosphate buffer, pH 2.5, containing 10 mg/ml of the cyclodextrin. The assay was linear in the range of 0.06–5.0% of the impurities based on a concentration of 2.0 mg/ml dexamphetamine sulfate in the sample solution. Analysis of commercial dexamphetamine sulfate samples revealed the presence of 3–4% of levoamphetamine while norephedrine or norpseudoephedrine could not be detected, indicating that the compound was prepared by fractionated crystallization of racemic amphetamine. Comparison with polarimetric measurements indicated that dexamphetamine with an enantiomeric excess as low as 80% still passes the pharmacopeial test of specific rotation while an amount of 0.06% of levoamphetamine can be detected by capillary electrophoresis.     

手性药物的质量控制研究

文中结合研发实例重点解读了《手性药物药学研究技术指导原则》中的药学研究思路与质量控制研究及稳定性研究等章节的内容,并归纳总结了在手性药物研发中的关键问题与常见问题。     

RP-HPLC法测定盐酸洛美沙星及其杂质的含量

采用RP－HPLC法测定盐酸洛美沙星及其杂质的含量。色谱柱：YWG－C18（4．6mm×250mm，10μm），流动相：庚磺酸钠-磷酸二氢钾溶液－甲醇－磷酸（49：51：0．7），检测波长：287um。含量测定采用外标法定量，平均回收率为98．6％（RSD=1．06％）。杂质检查用面积归一化法。     

EMS in Viracept—Initial (‘traditional’) assessment of risk to patients based on linear dose response relations

Prior to having performed in depth toxicological, genotoxicological and DMPK studies on ethyl methanesulfonate (EMS) providing solid evidence for a thresholded dose response relationship, we had prepared and shared with regulatory authorities a preliminary risk estimate based on standard linear dose–effect projections. We estimated that maximal lifetime cancer risk was in the order of 10⁻³ (for lifetime ingestion of the maximally contaminated tablets) or 10⁻⁴ for the exposure lasting for 3 months. This estimate was based on a lifetime cancer study with methyl methanesulfonate (MMS; as insufficient data were available for EMS) in rodents and default linear back extrapolation. Analogous estimates were made specifically for breast cancer based on short term tumorigenicity studies with EMS in rats, for the induction of heritable mutations based on specific locus and dominant lethal tests in mice and for the induction of birth defects based on teratogenicity studies in mice. We concluded that even under worst case assumptions of linear dose relations the chance of experiencing these adverse effects would be very small, comprising at most a minute additional burden among the background incidence of the patients.     

Analytical control of genotoxic impurities in the pazopanib hydrochloride manufacturing process

Pharmaceutical regulatory agencies are increasingly concerned with trace-level genotoxic impurities in drug substances, requiring manufacturers to deliver innovative approaches for their analysis and control. The need to control most genotoxic impurities in the low ppm level relative to the active pharmaceutical ingredient (API), combined with the often reactive and labile nature of genotoxic impurities, poses significant analytical challenges. Therefore, sophisticated analytical methodologies are often developed to test and control genotoxic impurities in drug substances. From a quality-by-design perspective, product quality (genotoxic impurity levels in this case) should be built into the manufacturing process. This necessitates a practical analysis and control strategy derived on the premise of in-depth process understanding. General guidance on how to develop strategies for the analysis and control of genotoxic impurities is currently lacking in the pharmaceutical industry. In this work, we demonstrate practical examples for the analytical control of five genotoxic impurities in the manufacturing process of pazopanib hydrochloride, an anticancer drug currently in Phase III clinical development, which may serve as a model for the other products in development. Through detailed process understanding, we implemented an analysis and control strategy that enables the control of the five genotoxic impurities upstream in the manufacturing process at the starting materials or intermediates rather than at the final API. This allows the control limits to be set at percent levels rather than ppm levels, thereby simplifying the analytical testing and the analytical toolkits to be used in quality control laboratories.     

萘甲异喹对大鼠心肌细胞Ca~(2+)内流的影响

目的研究萘甲异喹（NI）对大鼠心肌细胞外Ca(2+)内流的影响。方法：应用钙离子荧光指示剂Fura－2检测。结果：NI（3，10μmol·L(-1)）和维拉帕米（0．3μmol·L(－1)）对静息状态下心肌细胞内Ca(2+)浓度无影响，但可浓度依赖地抑制高钾（60mmol·L(-1)）和异丙肾上腺素（lμmol·L(－1)）引起的心肌细胞内Ca(2+)浓度的升高，抑制率分别为29％±6％、49％±9％和26％±6％、40％±8％；NI对两种激动剂作用的抑制百分率无明显差异，而维拉帕米对高钾作用的抑制大于对异丙肾上腺素作用的抑制。结论：NI对心肌细胞电压依赖性钙通道以及和β受体有关的钙通道有阻断作用，NI可能是非选择性钙通道阻滞剂。     

盐酸环丙沙星纯化中微量有机杂质的分离与结构研究

用液相色谱法检测盐酸环丙沙星原药，发现一杂质峰。该杂质经分离，确证其结构为７－氯－１－环丙基－６－（１－哌嗪基）－１，４－二氢－４－氧代喹啉－３－羧酸盐酸盐（３）。     

萘甲异喹对心肌收缩张力和耗氧量的影响

采用离体猫右心室乳头肌及豚鼠左房肌条,比较了萘甲异喹和维拉帕米对其收缩张力和耗氧量的影响。结果表明:萘甲异喹和维拉帕米对钙离子所致收缩张力和耗氧量的增加均有显著的抑制作用,且依剂量呈线性下降关系,其作用可被提高外钙离子浓度所逆转。提示萘甲异喹和维拉帕米相似与钙离子之间有拮抗作用。     

甜叶菊质量标准

目的： 建立甜叶菊的检查、定性鉴别及含量测定方法,为其质量控制提供科学依据。 方法： 按照中国药典委员会对中药质量标准的技术要求,对甜叶菊进行了性状、显微及薄层色谱鉴别,并对杂质、水分、总灰分、醇浸出物及指标成分（甜菊苷及莱鲍迪苷A）含量进行测定。 结果： 性状、显微鉴别、薄层色谱鉴别及含量测定方法重复性好,专属性强;根据24批甜叶菊分析结果,拟定甜叶菊杂质不得过4%,水分不得过11%,总灰分不得过9%,醇浸出物不得低于41%,甜菊苷含量不得低于2%,莱鲍迪苷A含量不得低于3%。 结论： 建立的检查、定性鉴别及含量测定方法,能有效控制甜叶菊的质量。     

液相色谱-质谱联用技术鉴定奥美沙坦酯有关物质

目的:采用液相色谱-质谱联用技术对奥美沙坦酯中有关物质进行结构鉴定。方法:采用LiChrospher C8(250 mm×4.6 mm,5μm)色谱柱,以甲醇-醋酸铵缓冲液为流动相梯度洗脱,对奥美沙坦酯有关物质进行分离;采用LC-MS/MS电喷雾正离子化测定各有关物质的相对分子质量和二级质谱,并进行结构解析。结果:检测到奥美沙坦酯粗品中11个有关物质,并推测出它们的化学结构均为奥美沙坦母核结构未发生变化的不同取代咪唑和四氮唑联苯衍生物。结论:色谱-质谱联用技术能够有效地用于药物中有关物质的鉴定,奥美沙坦酯有关物质研究可为其质量控制和工艺优化提供参考依据。