中文摘要：

以烟酸、苯甲酸、对硝基苯甲酸三种临床上有意义的小分子药物为模型药物，通过两步法把这类带有羧基的小分子药物以可降解的酯键连接到聚乙二醇（PEG）上，产物收率达80％～85％。由酯键的降解达到对小分子药物的缓释.对于所合成的大分子前药用IR，^1H-NMR，DSC进行表征，说明小分子药物键合到PEG上；产物可溶于绝大多数有机溶剂；提高了在水中的溶解性能。着重以PEG烟酸酯为例进行详细的讨论。

英文摘要：

In this paper, nicotinic acid, benzoic acid and p-nitrobenzoic applied in clinical were used as the model drugs. Small molecular drugs with carboxyl were PEGylated via degradable ester bonds by two-step process. The yield of products were 80 % --85 %. The small molecular drugs will be released by the degradation of ester bonds. The macromolecular prodrugs were characterized by IR, ^1H- NMR and DSC. The results suggeste that small molecular drugs are conjugated to PEG. Products are dissolvable in most organic solvents such as CH2Cl2, THF, CH3CH2OH, CHCl3, CH3COCH3,DMF, DMSO. The solubility of the products has been improved in aqueous solutions. The example of PEG- （nicotinic acid）2 had been discussed detailedly.