Application of sorption--desorption moisture transfer modeling to the study of chemical stability of a moisture sensitive drug product in different packaging configurations.

The sorption--desorption moisture transfer (SDMT) model was used to predict the effect of desiccant quantity, tablet quantity and tablet initial moisture content on the relative humidity inside high density polyethylene (HDPE) bottles containing a moisture sensitive drug product, roxifiban tablets. The effect of these variables on the stability of roxifiban tablets in the HDPE bottles was also evaluated. There was a good correlation between the calculated relative humidity values inside the package and stability results. Tablet degradant concentration increased with the increase in the relative humidity calculated by the SDMT model. Desiccant quantity was the most important factor in controlling degradation rate, which decreased as the quantity of desiccant in the bottle was increased. For a given desiccant quantity, degradation rate increased with an increase in the weight of tablets in the bottle. The inclusion of a desiccant in the package significantly reduced the effect of initial tablet moisture content on stability. Nevertheless, the effect of initial moisture content was still discernible. This study demonstrated the practical utility of the SDMT model in understanding the correlation between packaging variables and the stability of a moisture sensitive product.