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DISSOLUTION OF TAMOXIFEN IN BIORELEVANT MEDIA. A TWO PHASE RELEASE MODEL

ION MIRCIOIU¹, VALENTINA ANUTA^2*, NAGWA IBRAHIM², CONSTANTIN MIRCIOIU²

1 University of Medicine and Pharmacy Targu Mures , Romania
2 UMF Carol Davila, Faculty of Pharmacy, 6 Traian Vuia Str., Bucharest, Romania

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The present paper evaluates the release kinetics of tamoxifen from tablets, in biorelevant media as a prediction of the in vivo behavior. Four biorelevant media have been chosen to model the composition of the gastric and intestinal contents before and after meal intake. Results indicated that the effects of bile secretion are greater than that of food-induced pH variations. As a consequence, the effect of the changes in the gastrointestinal content associated with food ingestion was predicted to be an increase in the bioavailability. A special characteristic of all dissolution curves was that a part more or less significant of tamoxifen was released immediately. After this initial phase the rate of the process looked rather like a diffusion controlled release. Analysis of data using Higuchi, Peppas and Weibull models indicated the best fitting was obtained in the case of Higuchi square root law. Weibull model was not applicable for the entire domain of concentrations a two phase regression analysis being the single applicable model.