Dextrans were first used in clinical practice in 1947. Raw dextran is produced by bacterial conversion of sucrose to a branched chain structure which is heterogeneous in composition. Further refinement is carried out by hydrolysis and fractionation. Clinically useful dextrans form only 1 percent of the total molecular spectrum of raw dextran. The two most frequently used dextrans are Dextran 40 and Dextran 70. These have molecular weights of 40,000 and 70,000 respectively. The use of average molecular weight to describe dextrans is generally unsatisfactory since an infinite variety of dextrans could meet a particular weight specification. Categorization of dextrans will be discussed in detail. Clinical uses include plasma expansion, antithrombogenesis and haemodilution. Major efforts to reduce the antigenically active components of clinically used dextrans have been made and manufacturers have identified the principal factors responsible for allergic responses. However, major allergic responses to dextran still cause clinicians great concern and the problem is by no means resolved.
右旋糖酐于1947年首次应用于临床实践。粗制右旋糖酐是通过细菌将蔗糖转化为组成不均一的支链结构而产生的。通过水解和分级分离进行进一步提纯。临床上有用的右旋糖酐仅占粗制右旋糖酐总分子谱的1%。两种最常用的右旋糖酐是右旋糖酐40和右旋糖酐70。它们的分子量分别为40,000和70,000。由于有无数种右旋糖酐可以满足特定的重量规格，所以用平均分子量来描述右旋糖酐通常并不令人满意。右旋糖酐的分类将详细讨论。临床用途包括扩容、抗血栓形成和血液稀释。人们已经做出了重大努力来减少临床使用的右旋糖酐的抗原活性成分，制造商也已经确定了导致过敏反应的主要因素。然而，对右旋糖酐的严重过敏反应仍然引起临床医生的极大关注，这个问题远未得到解决。
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