Acta Pharmaceutica, Vol. 56 No. 3, 2006.
Original scientific paper
Effect of the molecular size of carboxymethylcellulose and some polymers on the sustained release of theophylline from a hydrophilic matrix
MARTINS O. EMEJE
OLOBAYO O. KUNLE
SABINUS I. OFOEFULE
Abstract
The objective of this study was to investigate the influence of the molecular size of carboxymethylcellulose (cmc) and some hydrophobic polymer additives on the release properties of theophylline from the tablet matrices. The cmc matrices were prepared by the conventional wet granulation method. The granules were evaluated for angles of repose, bulk density, compressibility index, and porosity, while the tablets were subjected to hardness, friability and compression characteristics. All the tablet formulations showed acceptable pharmacotechnical properties. Low molecular size cmc (cmc-L) had the fastest drug release t50% values of 27 min, for medium size cmc (cmc-M) 55 min and high molecular size cmc (cmc-H) 200 min. Overall, results showed that drug release rate decreases with increase in molecular size of cmc. All the polymer additives ethylcellulose (ETC), cellulose acetate phthalate (CAP) and Eudragit l-100 (EUD) retarded theophylline release from cmc-L and cmc-H, with ethylcellulose having the most pronounced effect on cmc-L. Kinetic studies using Hixson-Crowell and Peppas-Ritger equations showed that different drug release mechanisms were involved in controlling drug dissolution from the tablets. Drug release mechanism was influenced by both the molecular size of cmc and the presence of polymer additives.
Keywords
carboxymethylcellulose; hydrophobic polymers; theophylline; sustained-release; release mechanism
Hrčak ID:
4543
URI
Publication date:
1.9.2006.
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