In-vitro and in-vivo evaluation of commercial and microencapsulated sustained release tablets containing diclofenac sodium

ABSTRACT

Diclofenac sodium microcapsules were prepared using the phase separation technique induced by non-solvent addition. Ethl1cellulose and Eudragit RS100 were used as well forming materials in two core wall ratios [1 1 and 1 2]. The prepared microcapsules were compressed into tablets without excipients. The influence of tableting type of wall forming material and the core wall ratio on the release pattern of the drug from microcapsules were determined in Ph 1.2 and pH 6.8. compression of the microcapsules significantly [p < 0.05] decreased the rate of drug release due to the reduction of the surface area. Less than 2.0% of the drug was released in 0.1N HC1 during the first two hours of dissolution from microcapsules before and after tableting. On the other hand, the dissolution results of the tableted ethy1cellulose microcapsules with 11 and 12 core wall ratios showed that 88.6 and 70.6% of the drug were released to the phosphate buffer solution, while only 45.0 and 24.4% of the drug in the tableted eudragit microcapsules was released within 8 h of dissolution. The tableted ethy1cellulose microcapsules with 12 core wall ratio showed almost identical release of the drug as that from commercial tablets therefore, it was chosen for bioavailability study in six beagle dogs. The in-vivo data showed that the tableted microcapsules gave bioavailability of 87.5% relative to that of the commercial voltaren retard tablets. The prepared tablets show that it is possible to use ethy1cellulose microcapsules to prepare tablets that are pharmaceutically and biologically equivalent to those of the commercially available voltaren retard tablets