Abstract

E. Camila Batista dos Santos and Maria Fernanda Gouveia da Silva

The objective of the present study was to estimate the influence of ethyl cellulose (EC) with different viscosity grades on in vitro drug release from EC matrix tablets containing Indomethacin. Four viscosity grades of EC (7, 10, 50 and 100 cp) were studied. The 90 - 125/μm particle size fraction was collected by manual dry sieving and the compression force was varied to produce tablets of equal hardness. The drug release from Indomethacin tablets was determined by dissolution testing as described in the United States Pharmacopoeia (USP). The tablets pore characteristics were studied using helium pycnometry and mercury porosimetry. The release rate constant ranged from 1.25 ± 0.98 for the 7cp viscosity grade tablets to 1.49 ± 1.02 for the 100cp viscosity grade tablets whereas porosity ranged from 5.6% ± 0.3 to 6.8 ± 0.1 when based on gaz pycnometry and from 3.9% ± 0.4 to 5.1 ± 0.2 when based on mercury intrusion. These results indicate that the release rates marginally increased with an increase in viscosity grade. The main explanation for the viscosity grade effect on release rates would be differences in tablet porosity.