EVALUATION OF SOME ADDITIVES AS RELEASE RETARDANTS IN SUSTAINED RELEASE THEOPHYLLINE TABLETS

Document Type : Original Article

Authors

Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Suez Canal University, Ismailia, Egypt.

Abstract

Sustained release matrix tablets involve mixing the active ingredient(s) with proper release retarding agent(s). In this study, theophylline anhydrous (THF) matrix tablets were prepared using different concentrations of magnesium stearate or ethylcellulose as release retarding materials. At certain concentrations, both substances were capable of retarding the drug release. However, high concentrations of magnesium stearate has led to poor physical properties such as low hardness and increased friability. On the contrary, increasing the concentration of ethylcellulose has improved both hardness and friability which may be regarded due to its binding properties. The optimum formulation was chosen on the basis of tablet mechanical properties and in vitro drug release. The selected tablet formulations had optimum hardness, low friability and acceptable dissolution pattern regarding to USP XXX dissolution regulations. Through applying kinetic equation models, the release mechanism of the drug from the selected formulations was found to follow Higuchi's kinetic model. This indicates that the drug release from the selected formulated tablets was mainly due to diffusion rather than matrix erosion.

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