Model Dependent and Independent Approaches to Compare In vitro Release Profiles from Ethylcellulose and Eudragit L100 Based Matrix Tablets

Abstract

The main objective of the present study was to compare the release profiles of ethylcellulose and
eudragit L100 based matrix tablets of naproxen. Dissolution studies were carried out by using United States
Pharmacopoeia-XXIII type-II dissolution apparatus. The granules were evaluated for angle of repose, bulk density,
compressibility index, total porosity and drug content. The tablets were subjected to thickness, diameter, hardness,
drug content, disintegration test, friability and in vitro release studies. The release rate was quantitatively determined
by a HPLC method. Matrix tablets based on 20% and 25% ethylcellulose and 25% eudragit L100 showed sustained
release up to 8 hours. The release patterns were evaluated using model-dependent approaches (zero order, first order,
Higuchi’s, Korsmeyer’s and Weibull’s model) and model-independent approach (ANOVA and the similarity factor,
f2). Most of the release patterns were fitted to Korsmeyer’s model with n values between 0.663 to 0.816, indicating
the release mechanisms were governed by both diffusion and erosion. From the Weibull equation, the shape
parameter was found to be sigmoid or S-shaped. Among the formulations, ECF-2 and EFU-6 were most similar to
ECF-3 according to f2 value. The MDT values were found to be increased with the increased concentration of
polymers. Ethylcellulose found to be most rate retarding than eudragit L100.