Effect of crystallinity of microcrystalline cellulose on the compactability and dissolution of tablets.

Microcrystalline cellulose (MCC) was pulverized with a vibrational rod mill. The degree of crystallinity of MCC decreased from 65.5 to 12.1% with pulverization time due to mechanochemical effect. Pulverized MCCs were compressed at 155.6 MPa using a compression test apparatus, and the two parameters relating to compactability, the B value and yield pressure, were calculated using a Heckel plot. These values were lowered as the degree of crystallinity of MCC became smaller. These results suggest that the crystal region and the amorphous region in MCC particles may be mainly fractured and deformed plastically during compression, respectively. Then the dissolution test was performed for the acetaminophen-MCC (10:90) tablets. Dissolution profiles showed an interesting phenomenon, namely, the dissolution rate of acetaminophen from MCC tablet decreased when the degree of crystallinity of MCC was in the range from 65.5 to 37.6%, however, it increased markedly when the degree of crystallinity of MCC was in the range from 25.8 to 12.1%. The amount of water absorbed into tablets changed in accord with the dissolution rates of acetaminophen from tablets. The dissolution data indicate that drug release can be modified by changing the degree of crystallinity of MCC.