为建立低分子肝素(LMWH)的国际标准,进行了国际性的协作研究。在13个国家的25所实验室中,参照未分级肝素(UFH)的国际标准,采用9种不同测定方法,测定了3种LMWH制剂。结果证实了前已出现的不平行的测定,实验室间的大的变异性和方法间的差异。用一种LMWH作为标准品测定另两种制剂,则测定平行,实验室之间的结果很接近。代号为85/600的安瓿装制剂被选定,因其有可能和大多数LMWH具有最好的一致性。其效价的确定,是用抗-Xa测定的平均值以及凝血酶和APTT测定的平均值,来表示这两类主要活性,此制剂已被WHO确定为LMWH的第一次国际标准。其效价分别为1680iu/安瓿和665iu/安瓿。 To establish an international standard for low molecular weight heparin (LMWH), an international collaborative study was conducted. In 25 laboratories in 13 countries, three LMWH formulations were determined by reference to the international standard for unfractionated heparin (UFH) using nine different assay methods. The results confirm the previously non-parallel determination, the large inter-laboratory variability, and the differences between the methods. Using one of the LMWH as a standard for the other two assays, the assays were parallel and the results were very similar between laboratories. Ampoule formulations, code 85/600, were chosen because of the best possible agreement with most LMWH. The titer is expressed as the mean of both the anti-Xa assay and the average of the thrombin and APTT determinations, both of which have been identified by WHO as the first international standard for LMWH. The titers were 1680iu / ampoule and 665iu / ampoule, respectively.