The invention relates to a method for high-yield preparation of an
icodextrin bulk drug by a single
enzyme system, which comprises the following steps: gelatinizing
starch at high temperature, adding alpha-thermoamylase for
hydrolysis, carrying out
ultrafiltration separation on primary enzymatic
hydrolysate to obtain high-molecular-weight
dextrin and alpha-thermoamylase, returning the high-molecular-weight
dextrin and the alpha-thermoamylase to a gelatinization tank for secondary enzymolysis, and combining
ultrafiltration permeates of the secondary enzymatic
hydrolysate and the primary enzymatic
hydrolysate, and performing molecular weight screening by
ultrafiltration to obtain
icodextrin of which the weight-average molecular weight and the number-average molecular weight simultaneously meet the requirements of alpha-1, 6 glucosidic bonds. On the basis of a traditional
icodextrin manufacturing process, the working procedures of recovering macromolecular
dextrin and performing secondary enzymolysis are added, and the yield can reach 85-91%. Particularly, new
amylase does not need to be additionally added in the secondary enzymolysis, the original
amylase is continuously used, new equipment is not added, the production cost increase is small, and the preparation efficiency is high.