As a result of its higher molecular mobility, the surface of an amorphous drug can grow crystals much more rapidly than the bulk, causing poor stability and slow dissolution of drug products. We show that a nanocoating of chitosan (a pharmaceutically acceptable polymer) can be deposited on the surface of amorphous indomethacin by electrostatic deposition, leading to significant improvement of physical stability, wetting by aqueous media, dissolution rate, powder flow, and tabletability. The coating condition was chosen so that the positively charged polymer deposits on the negatively charged drug. Chitosan coating is superior to gelatin coating with respect to stability against crystallization and agglomeration of coated particles.
Bibliographical noteFunding Information:
We thank the Bill and Melinda Gates Foundation for financial support, R. Teerekapibal for experimental assistance, and Niya Bowers, Phil Goliber, and Ellen Harrington for helpful discussions.
© 2019 American Chemical Society.
Copyright 2019 Elsevier B.V., All rights reserved.
- amorphous drug
- powder flow
- surface coating