Surface characterizations of spin-coated films of ethylcellulose and hydroxypropyl methylcellulose blends.

Films of pure ethylcellulose (EC) and hydroxypropyl methylcellulose (HPMC) polymers and EC/HPMC blends were prepared from solutions by spin coating where isopropyl alcohol (IPA), water, and IPA/water cosolvent were used as solvents. Surface structures of the films were investigated using optical microscopy, atomic force microscopy (AFM), and Raman mapping and spectroscopy. For the films prepared from EC/HPMC blend solutions using the IPA/water cosolvent, different domain structures such as islands or pits and phase separation between EC and HPMC were observed by optical microscopy and AFM.

Particle size limits to meet USP content uniformity criteria for tablets and capsules.

Content uniformity (CU) of pharmaceutical dosage units can be affected by active pharmaceutical ingredient (API) particle size and size distribution. Previous authors have estimated this impact but use of different particle size descriptors led to confusion and difficulty in applying the theoretical models developed. We show that when the same descriptors for particle size and distribution are used (i.