Nano-sized flake carboxymethyl cassava starch as excipient for solid dispersions.

Nano-sized excipients were used in solid dispersions (SD) to enhance the dissolution rate of poorly water-soluble drug in this study. Nano-sized flake carboxymethyl cassava starch (CMCS) was firstly synthesized under ultrasonic irradiation. Then acetylsalicylic acid (ASA) was selected as water insoluble drug model to prepare solid dispersions using three different kinds of excipients. SD1 was prepared using native cassava starch as carrier. SD2 and SD3 were prepared using nano-sized CMCS (degree substitution, DS=1.15, 100-400 nm) and micro-sized CMCS (DS=0.36, 8-28 μm), respectively. These solid dispersions were characterized by powder X-ray diffractometry, scanning electron micrographs and dissolution. The results suggested that the SD2 prepared by nano-sized CMCS had much better dispersion capability for the drug than the other two solid dispersions. And the dissolution rate of SD2 was considerably higher than that of pure drug. These results indicated that the nanoscale CMCS was a kind of good carrier for solid dispersion to improve the solubility of poorly water-soluble drugs.