美国药典24版细菌内毒素检查法文档

美国药典24版细菌内毒素检查法本文是USP24细菌内毒素检查法（BACTERLAL ENDOTOXINS TEST）的译文，但目前执行的标准是USP24版第二增补本（USP—NF19 Second Supplement）的细菌内毒素检查法，读者可对照学习，从中可看出USP24细菌内毒素检查的不足之处。

本文将介绍用鲎试剂检测样品内或样品上存在的细菌内毒素浓度的方法。

鲎试剂（Limulus Amebocyte,LAL）来自鲎的循环细胞，经水提取而行，制备和检验后，用于凝固法。

反应的终点是将供检样品稀释后，与平行稀释的参考内毒素标准进行直接比较得到的。

测得的内毒素含量用规定的内毒素单位表示。

鲎试剂也是用浊度法或显色法来读取数据的，这些试齐只要能满足这些选择方法的要求，就可以使用。

在做试验时，需要先做出一条标准曲线，并用该曲线计算供检样品的内毒素含量，包括样品和对照液加鲎试剂后的培育时间和在分光光度计上读取光密度时使用的波长等操作，都应该事先规定好。

如果是终点浊度法，则到达培育期后，应立刻读取读数。

而动力学检测（凶手浊度法和显色法），光密度的测定是贯穿于整个反应期间，而用于计算结果的百分数就是从这些读数中计算出来的。

在用终点法的显色法检测时，在到达事先规定的反应时间后，添加停止酶反应的试剂使反应停止后，再读取数据。

1、参考内毒素标准与对照内毒素标准参考内毒素标准（Reference standard endotoxin,RSE）是美国药典（USP）的内毒素参考标准，其效价为每瓶10 000个USP内毒素单位（EU）。

每瓶参考内毒素标准加5ml鲎试剂用水（LAL Reagent Watet），用旋转搅拌器间歇搅拌30min使其溶解，制成原液，用这一原液制作合适的系列稀释。

原液应保存于冰箱中，用于以后的稀释，但保存时间不得超过14d。

用前，用旋转搅拌器强力搅拌至少3min，每一步稀释，至少搅拌30s，然后才能用它稀释下一步。

鲎试剂－LAL，中国药典和美国药典的内毒素检测要求鲎试剂是从栖生于海洋的节肢动物“鲎”的兰色血液中提取变形细胞溶解物，经低温冷冻干燥而成的生物试剂，专用于细菌内毒素检测。

鲎试验法是国际上至今为止检测内毒素最好的方法，它简单﹑快速﹑灵敏﹑准确，因而被欧美药典及我国药典定为法定内毒素检查法，并已被世界各国所采用。

目前国际上销售的鲎试剂有两种，一种称美洲鲎试剂（Limulus Amebocyte Lysate），缩写为LAL，由美国生产；另一种称东方鲎鲎试剂（Tachypleus Amebocyte Lysate），缩写为TAL。

实验证明：美洲鲎试剂-LAL比东方鲎试剂LAL更纯洁，检测效果更好。

TAL检查内毒素有很多方法，目前应用最广泛的是凝胶法，此外还有动态浊度法﹑显色基质法,比色法等。

其用途有以下几方面：1. 药检：用于注射药品﹑放射性药物﹑生物制品﹑注射器及生产工艺流程中的内毒素检测；2. 临床：用于检测病人各种体液中的内毒素含量；3. 其他：用于检测水或食品中的内毒素含量。

2005年版中国药典《细菌内毒素检查法-鲎试剂法》(鲎试剂－LAL法)本法系利用鲎试剂来检测或量化由革兰阴性菌产生的细菌内毒素，以判断供试品中细菌内毒素的限量是否符合规定的一种方法。

细菌内毒素检查包括两种方法，即凝胶法和光度测定法，后者包括浊度法和显色基质法。

供试品检测时，可使用其中任何一种方法进行试验。

当测定结果有争议时，除另有规定外，以凝胶法结果为准。

细菌内毒素的量用内毒素单位（EU）表示。

细菌内毒素国家标准品系自大肠杆菌提取精制而成，用于标定、复核、仲裁鲎试剂灵敏度和标定细菌内毒素工作标准品的效价。

细菌内毒素工作标准品系以细菌内毒素国家标准品为基准标定其效价，用于试验中鲎试剂灵敏度复核、干扰试验及设置的各种阳性对照。

凝胶法细菌内毒素检查用水系指内毒素含量小于0.015EU/ml的灭菌注射用水。

定量测定用的细菌内毒素检查用水，其内毒素的含量应小于0.005EU/ml。

BACTERIAL ENDOTOXINS TEST <85> USP35Portions of this general chapter have been harmonized with the corresponding texts ofthe European Pharmacopoeia and/or the Japanese Pharmacopoeia. Those portions that are not harmonized are marked with symbols () to specify this fact.这一章节已经和欧洲药典（EP）与日本药典（JP）统一。

没有统一的部分已经用标记出来。

The Bacterial Endotoxins Test (BET) is a test to detect or quantify endotoxins from Gram-negative bacteria using amoebocyte lysate from the horseshoe crab (Limulus polyphemus or Tachypleus tridentatus).细菌内毒素检查法（BET）是通过鲎的阿米巴细胞溶解产物来检测或定量来自革兰氏阴性菌的内毒素。

There are three techniques for this test: the gel-clot technique, which is based on gel formation; the turbidimetric technique, based on the development of turbidity after cleavage of an endogenous substrate; and the chromogenic technique, based on the development of color after cleavage of a synthetic peptide-chromogen complex. Proceed by any of the three techniques for the test. In the event of doubt or dispute, the final decision is made based upon the gel-clot technique unless otherwise indicated in the monograph for the product being tested. The test is carried out in a manner that avoids endotoxin contamination.细菌内毒素检查法有3种：凝胶法，基于凝胶的形成；浊度法，BACTERIAL ENDOTOXINS TEST USP32Portions of this general chapter have been harmonized with the corresponding texts of the European Pharmacopeia and/or the Japanese Pharmacopeia. Those portions that are notharmonized are marked with symbols () to specify this fact.This chapter provides a test to detect or quantify bacterial endotoxins that may be present in or on the sample of the article(s) to which the test is applied. It uses Limulus Amebocyte Lysate (LAL) obtained from the aqueous extracts of circulating amebocytes of horseshoe crab (Limulus polyphemus or Tachypleus tridentatus) which has been prepared and characterized for use as anLAL Reagent.1There are two types of techniques for this test: the gel-clot techniques, which are based on gel formation, and the photometric techniques. The latter include a turbidimetric method, which is based on the development of turbidity after cleavage of an endogenous substrate, and a chromogenic method, which is based on the development of color after cleavage of a synthetic peptide-chromogen complex. Proceed by any one of these techniques, unless otherwise indicated in the monograph. In case of dispute, the final decision is based on the gel-clot techniques, unless otherwise indicated in the monograph.In the gel-clot techniques, the reaction endpoint is determined from dilutions of the material under test in direct comparison with parallel dilutions of a reference endotoxin, and quantities of endotoxin are expressed in USP Endotoxin Units (USP-EU).[NOTE—One USP-EU is equal to one IU of endotoxin.]Because LAL Reagents have been formulated to be used also for turbidimetric or colorimetric tests, such tests may be used to comply with the requirements. These tests require the establishment of a standard regression curve; the endotoxin content of the test material is determined by interpolation from the curve. The procedures include incubation for a preselected time of reacting endotoxin and control solutions with LAL Reagent and reading of the spectrophotometric light absorbance at suitable wavelengths. In the endpoint turbidimetric procedure the reading is made immediately at the end of the incubation period. In the endpoint colorimetric procedure the reaction is arrested at the end of the preselected time by the addition of an enzyme reaction-terminating agent prior to the readings. In the turbidimetric and colorimetric kinetic assays the absorbance is measured throughout the reaction period and rate values are determined from those readings.APPARATUS AND GLASSWAREDepyrogenate all glassware and other heat-stable materials in a hot-air oven using a validatedprocess.2Commonly used minimum time and temperature settings are 30 minutes at 250. If employing plastic apparatus, such as microplates and pipet tips for automatic pipetters, useonly that which has been shown to be free of detectable endotoxin and not to interfere with the test.[NOTE—In this chapter, the term “tube” includes any other receptacle such as a micro-titer well.]PREPARATION OF THE STANDARD ENDOTOXIN STOCK SOLUTION AND STANDARD SOLUTIONS The USP Endotoxin RS has a defined potency of 10,000 USP Endotoxin Units (EU) per vial. Constitute the entire contents of 1 vial of the RSE with 5 mL of LAL Reagent Water3, mixintermittently for 30 minutes, using a vortex mixer, and use this concentrate for making appropriate serial dilutions. Preserve the concentrate in a refrigerator for making subsequent dilutions for not more than 14 days. Mix vigorously, using a vortex mixer, for not less than 3 minutes before use. Mix each dilution for not less than 30 seconds before proceeding to make the next dilution. Do not store dilutions, because of loss of activity by adsorption, in the absence of supporting data to the contrary.Preparatory TestingUse an LAL Reagent of confirmed label sensitivity.The validity of test results for bacterial endotoxins requires an adequate demonstration that specimens of the article or of solutions, washings, or extracts thereof to which the test is to be applied do not of themselves inhibit or enhance the reaction or otherwise interfere with the test. Validation is accomplished by performing the inhibition or enhancement test described under each of the three techniques indicated. Appropriate negative controls are included. Validation must be repeated if the LAL Reagent source or the method of manufacture or formulation of the article is changed.Preparation of Sample SolutionsPrepare sample solutions by dissolving or diluting drugs or extracting medical devices using LAL Reagent Water. Some substances or preparations may be more appropriately dissolved, diluted, or extracted in other aqueous solutions. If necessary, adjust the pH of the solution (or dilution thereof) to be examined so that the pH of the mixture of the LAL Reagent and sample falls within the pH range specified by the LAL Reagent manufacturer. This usually applies to a product with a pH in the range of 6.0 to 8.0. The pH may be adjusted using an acid, base, or suitable buffer as recommended by the LAL Reagent manufacturer. Acids and bases may be prepared from concentrates or solids with LAL Reagent Water in containers free of detectable endotoxin. Buffers must be validated to be free of detectable endotoxin and interfering factors.DETERMINATION OF MAXIMUM VALID DILUTION (MVD)The Maximum Valid Dilution is the maximum allowable dilution of a specimen at which the endotoxin limit can be determined. It applies to injections or to solutions for parenteral administration in the form constituted or diluted for administration, or, where applicable, to theamount of drug by weight if the volume of the dosage form for administration could be varied. The general equation to determine MVD is:MVD = (Endotoxin limit × Concentration of sample solution)/()where the concentration of sample solution and are as defined below. Where the endotoxin limit concentration is specified in the individual monograph in terms of volume (in EU per mL), divide the limit by, which is the labeled sensitivity (in EU per mL) of the LAL Reagent, to obtainthe MVD factor. Where the endotoxin limit concentration is specified in the individual monograph in terms of weight or Units of active drug (in EU per mg or in EU per Unit), multiply the limit by the concentration (in mg per mL or in Units per mL) of the drug in the solution tested or of the drug constituted according to the label instructions, whichever is applicable, and dividethe product of the multiplication by, to obtain the MVD factor. The MVD factor so obtained is the limit dilution factor for the preparation for the test to be valid.ESTABLISHMENT OF ENDOTOXIN LIMITSThe endotoxin limit for parenteral drugs, defined on the basis of dose, is equal to K/M,4where K is the threshold human pyrogenic dose of endotoxin per kg of body weight, and M isequal to the maximum recommended human dose of product per kg of body weight in a single hour period.The endotoxin limit for parenteral drugs is specified in individual monographs in units such as EU/mL, EU/mg, or EU/Unit of biological activity.GEL-CLOT TECHNIQUESThe gel-clot techniques detect or quantify endotoxins based on clotting of the LAL Reagent in the presence of endotoxin. The concentration of endotoxin required to cause the lysate to clot under standard conditions is the labeled sensitivity of the LAL Reagent. To ensure both the precision and validity of the test, tests for confirming the labeled LAL Reagent sensitivity and for interfering factors are described under Preparatory Testing for the Gel-Clot Techniques.Preparatory Testing for the Gel-Clot TechniquesTest for Confirmation of Labeled LAL Reagent Sensitivity—Confirm the labeled sensitivity using at least 1 vial of the LAL Reagent lot. Prepare a series of two-fold dilutions of the USP EndotoxinRS in LAL Reagent Water to give concentrations of 2,, 0.5, and 0.25, where is as defined above. Perform the test on the four standard concentrations in quadruplicate and。

1143 细菌内毒素检查法本法系利用鲎试剂来检测或量化由革兰阴性菌产生的细菌内毒素，以判断供试品中细菌内毒素的限量是否符合规定的一种方法。

细菌内毒素检查包括两种方法，即凝胶法和光度测定法，后者包括浊度法和显色基质法。

供试品检测时，可使用其中任何一种方法进行试验。

当测定结果有争议时，除另有规定外，以凝胶限度试验结果为准。

本试验操作过程应防止内毒素的污染。

细菌内毒素的量用内毒素单位（EU）表示，1EU与1个内毒素国际单位（IU）相当。

细菌内毒素国家标准品系自大肠埃希菌提取精制而成，用于标定、复核、仲裁鲎试剂灵敏度、标定细菌内毒素工作标准品的效价，干扰试验及检查法中编号B和C溶液的制备、凝胶法中鲎试剂灵敏度复核试验、光度测定法中标准曲线可靠性试验。

细菌内毒素工作标准品系以细菌内毒素国家标准品为基准标定其效价，用于干扰试验及检查法中编号B和C溶液的制备、凝胶法中鲎试剂灵敏度复核试验、光度测定法中标准曲线可靠性试验。

细菌内毒素检查用水应符合灭菌注射用水标准，其内毒素含量小于0.015EU/ml（用于凝胶法）或0.005EU/ml（用于光度测定法），且对内毒素试验无干扰作用。

试验所用的器皿需经处理，以去除可能存在的外源性内毒素。

耐热器皿常用干热灭菌法（250℃、30分钟以上）去除，也可采用其他确证不干扰细菌内毒素检查的适宜方法。

若使用塑料器皿，如微孔板和与微量加样器配套的吸头等，应选用标明无内毒素并且对试验无干扰的器具。

供试品溶液的制备某些供试品需进行复溶、稀释或在水性溶液中浸提制成供试品溶液。

必要时，可调节被测溶液（或其稀释液）的pH值，一般供试品溶液和鲎试剂混合后溶液的pH值在6.0～8.0的范围内为宜，可使用适宜的酸、碱溶液或缓冲溶液调节pH值。

酸或碱溶液须用细菌内毒素检查用水在已去除内毒素的容器中配制。

缓冲液必须经过验证不含内毒素和干扰因子。

内毒素限值的确定药品、生物制品的细菌内毒素限值（L）一般按以下公式确定：L=K/M式中 L为供试品的细菌内毒素限值，一般以EU/ml、EU/mg或EU/U （活性单位）表示；K为人每千克体重每小时最大可接受的内毒素剂量，以EU/（kg·h）表示，注射剂K=5 EU/（kg·h），放射性药品注射剂K=2.5 EU/（kg·h），鞘内用注射剂K=0.2 EU/（kg·h）；M为人用每千克体重每小时的最大供试品剂量，以ml/（kg·h）、mg/（k g·h）或U/（kg·h）表示，人均体重按60kg计算，人体表面积按1.62㎡计算。

（85）细菌内毒素检查法✹本章内容已与《欧洲药典》和/或《日本药局方》相应的内容统一，不一致的部分用符号（✹✹）标记。

✹细菌内毒素检查法（BET）系利用鲎试剂（美洲鲎或中国益）检测或量化革兰阴性菌产生的细菌内毒素。

可采用三种技术进行细菌内毒素检查：基于凝胶形成的凝胶法；基于内源性底物裂解后浊度变化的比浊法；基于合成胁显色基质复合物裂解后发生颜色变化的显色法。

可采用上述任意一种方法进行检测。

当对测定结果有怀疑或争议时，除另有规定外，以凝胶法测定结果为准。

本法操作过程中应防止内毒素的污染。

器具应按照经过验证的程序将所有玻璃器皿和其他热稳定材料置于干热烤箱中去除热原。

✹①✹通常使用的最低温度和最短时间为250℃加热30分钟。

如果使用多孔板和微量加样器吸头等塑料器具时，只有证明其不含有可检出的内毒素并对试验无干扰方可使用。

（注：本章中的“管”包括微孔板中的孔等所有反应容器。

）试剂和试液试剂是由鲎（美洲鲎或中国鲎）的阿米巴细胞（白细胞）溶解产物制得的冻干品。

这种试剂必须是按照权威机构认定的规程生产的产品。

（注：除内毒素外，鲎试剂也与P葡聚糖反应。

通过消除G因子或抑制G因子反应系统，能够制得不与葡聚糖反应的鲎试剂，此种鲎试剂可用于葡聚糖存在情况下的内毒素检查。

）内毒素检查（BET）用水在检测限内不与鲎试剂产生凝集反应的注射用水或用其他方法制备的水。

鲎测试液将鲎试剂溶解于内毒素检查用水或鲎试剂生产企业推荐的缓冲液中，轻轻混匀。

复溶的鲎试剂须按照生产企业的规定冷藏或冷冻保存。

溶液的制备内毒素标准品贮备液使用经现行WHO国际内毒素标准品标定过的美国药典内毒素标准品配制内毒素标准品贮备液。

按照包装说明书和标签上的规定制备、贮存贮备液。

内毒素的单位用EU表示。

[注：1个美国药典内毒素单位（EU）等于1个国际内毒素单位（IU）]内毒素标准品溶液将内毒素标准品贮备液充分混匀后，用内毒素检查用水进行连续稀释。

为避免因内毒素的吸附而导致失活，配制后的稀释液应尽快使用。