Surelease as granulating liquid in preparation of sustained release matrices of ethylcellulose and theophylline

Abstract

Objectives: Use of Surelease as a granulation liquid in preparation of granules and matrices of theophylline and ethylcellulose was evaluated.

Materials and methods: Physical mixtures (at 1:1 or 1:1.5 drug:polymer) were granulated using water, Surelease or diluted Surelease as granulating liquid. The granule characteristics (shape, size, flow rate, mechanical properties, friability and release profile) were studied. Afterwards, matrices were manufactured and their crushing strengths, friability and release profiles were determined.

Results: Granulation produced agglomerated particles with better flowability than physical mixtures. Change of granulation liquid from water to Surelease or diluted Surelease led to the marginal increase in size of granules at 1:1 drug:polymer, however, the flow rate and Carr’s index were considerably improved. The hardness, elastic modulus, friability and rate of drug release were not affected by granulation liquid. Increase in polymer content resulted in reduction in size of granules, flow rate, elastic modulus and rate of drug release. However hardness of the granules was unaffected. Granulation process and granulation liquid did not affect the hardness, and dissolution rate of matrices at 1:1 drug:polymer, while the use of Surelease or diluted Surelease as a granulating liquid, increased the hardness and decreased drug release rate at 1:1.5 drug:polymer. Matrices prepared from Surelease or diluted Surelease showed similar characteristics.

Conclusions: Surelease is a suitable granulating liquid for preparation of ethylcellulose matrices especially when high amount of polymer is used and could not only improve the flow and compatibility of the granules, but also help in reducing the rate of drug release.

• Ethylcellulose
• matrix
• surelease
• sustained release
• wet granulation

Acknowledgements

The authors acknowledge Colorcon for free supply of Surelease samples.

Declaration of interest

This work is a part of a Pharm. D student thesis that was supported by a grant from Vice Chancellor for Research and Technology (Grant No. 900114), Mashhad University of Medical Sciences.