Formulation Effects on the Thermomechanical Properties and Permeability of Free Films and Coating Films: Characterization of Cellulose Acetate Films - Pharmaceutical Technology

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Formulation Effects on the Thermomechanical Properties and Permeability of Free Films and Coating Films: Characterization of Cellulose Acetate Films
The authors investigate the effects of a polyethylene glycol plasticizer and water on cellulose acetate film properties.

Pharmaceutical Technology
Volume 33, Issue 3, pp. 88-100


Understanding formulation factor effects on free-film and coating-film properties would provide guidelines for selecting a formulation in the early design stage of developing semipermeable membranes. The results from this study demonstrated that formulation factors such as plasticizer and water level, signifantly affect free-film properties and coating performance. With increasing plasticizer level, the mechanical strength of the free films decreased and the permeability of the films increased. With the interaction of plasticizer and water, the effects on the properties of free films were even greater. Although there were no significant differences in free film properties between CA-398-10NF-EP and CA-398-10TG, the permeability of coating films increased with decreasing acetyl content in CA polymers. The acetyl content over a range of about 1.0% affected permeability of coating films at some degree and the effects were largely dependent on the formulation. With higher plasticizer level and water level in the formulation, the acetyl content only slightly affected the permeability of the coating film. This study demonstrates that it is important to design a robust formulation to reduce the variability of a finished product. It should be realized that besides formulation factors, processing conditions are key controls in ensuring product quality and keeping the release profile of a product in a desirable range.

Jinghua Yuan* is a principal technical service representative, Doug Dunn is a senior lab technician, Nancy M. Clipse is a research analyst, and Ray J. Newton, Jr. is a senior research associate, all at Formulation Products Lab, Pharmaceutical Formulations Group, Eastman Chemical Company, Kingsport, TN 37662, tel. 423.229.8627, fax 423.224.0414,

*To whom all correspondence should be addressed.

Submitted: May 6, 2008. Accepted: Oct. 1, 2008.

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