Effect of drug loading and molecular weight of cellulose acetate propionate on the release characteristics of theophylline microspheres

Microspheres with 40, 50, and 60% drug loading of anhydrous theophylline core material were prepared by the emulsion-solvent evaporation method. Three different molecular weights of cellulose acetate propionate were used as encapsulating polymers. The geometric mean diameter of the microspheres incr...

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Bibliographic Details
Published in:Pharmaceutical research 1991-11, Vol.8 (11), p.1396-1400
Main Authors: SHUKLA, A. J, PRICE, J. C
Format: Article
Language:English
Subjects:
Biological and medical sciences
Capsules
Cellulose - analogs & derivatives
General pharmacology
Medical sciences
Microscopy, Electron, Scanning
Microspheres
Molecular Weight
Particle Size
Pharmaceutical technology. Pharmaceutical industry
Pharmacology. Drug treatments
Theophylline - administration & dosage
Viscosity
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Summary:Microspheres with 40, 50, and 60% drug loading of anhydrous theophylline core material were prepared by the emulsion-solvent evaporation method. Three different molecular weights of cellulose acetate propionate were used as encapsulating polymers. The geometric mean diameter of the microspheres increased with drug loading for all polymers. Dissolution rate for a given particle size fraction also increased with drug loading for all polymers. Higuchi/Baker-Lonsdale spherical matrix dissolution kinetics were followed by narrow particle size fractions of the microspheres. A linear relationship between the T-50% (time required for 50% of the drug to be released) and the square of microsphere diameter was observed with all three molecular weights of the encapsulants. The slowest drug release was obtained with the high molecular weight polymer, which also produced the smoothest microspheres.
ISSN:0724-8741
1573-904X
DOI:10.1023/A:1015801207091