Characterization of polymeric dispersions of dimenhydrinate in ethyl cellulose for controlled release

Granulations of dimenhydrinate (DMH) were prepared using various concentrations of ethyl cellulose (EC) by the solid dispersion technique. Characterization was done using thermal analysis, powder X-ray diffraction, infrared spectroscopy, optical microscopy and dissolution studies. Humidity studies were performed to investigate the effect of moisture on the drug and solid dispersions. It was seen that the crystalline drug was converted into its amorphous form in all the granulations. There was no chemical interaction between the DMH and EC. The thermal decomposition of drug in the granules was not affected. Dissolution studies revealed that the drug release from the granulations was significantly reduced as compared to the pure drug. As the amount of ethyl cellulose increased, the drug release rate decreased and the drug release kinetics showed a better fit to zero-order kinetics. Humidity studies showed that the drug and granulations remained stable in conditions not exceeding 70%RH. At high humidity of 100%RH, there was formation of the hydrate crystal forms of the drug in the pure drug samples and granules with 1:1 DMH-EC content whereas the granules with higher polymer content did not show any significant changes indicating better drug stability in the granules.