Introduction:
A sustained release system for losartan potassium designed to delay its residence
time in the stomach through the preparation of solvent evaporation technique-based floating microspheres.
The influence of the different grades of Ethocel™ such as 4 cps, 10 cps, and 22 cps as well as the drug: polymer
ratio on various properties of microspheres were tested.
Methods:
Thermal and functional analysis revealed no interaction between the encapsulated drug and polymer.
The results indicated that the mean diameter of microspheres increased with a change in grades of ethyl
cellulose relating to viscosity. However, the drug incorporation efficiency within ethyl cellulose microspheres
decreased with increasing viscosity of ethyl cellulose.
Results:
The bulk density of the formulations was proportionally dependent on concentration and the viscosity
of the polymer, which resulted in a decrease in floating capacity from 90.02% to 73.58%. Moreover, the
drug release was indirectly proportional to the viscosity of ethyl cellulose tested. The in vitro release profile
exhibited a burst effect with a biphasic release pattern following Fickian diffusion, indicating a diffusioncontrolled
release mechanism.
Conclusion:
The results demonstrated that the viscosity of ethyl cellulose significantly affects the floating capacity
and drug release pattern from microspheres.