Controlled Release Formulation of Indomethacin Prepared With Bee Glue Extracts

Purpose: To prepare and evaluate new sustained release formulations of indomethacin based on extracts of propolis (bee glue). Methods: Standardization of propolis (bee glue) extracts was performed by high performance liquid chromatography (HPLC) and determination of the values of fat and fixed oils. Several indomethacin capsule formulations (F1 - F18) containing varying amounts of chloroform (0.75 - 75 mg) and ethanol extracts (30 - 75 mg) of propolis were prepared. The dissolution rate of the formulations was evaluated by USP dissolution (rotating basket) method I and the release data subjected to various kinetic models. Probable interaction between the drug andpropolis extracts was studied by differential scanning calorimetry (DSC). Results: The results show that, although the release rate of formulations F1 - F7 did not show any significant difference (p 0.05) compared to F18 as blank, the other formulations did. DSC results indicate that incorporation of propolis extract in the formulations lowered indomethacin melting point by between 5 and 30 °C, indicating interaction between the drug and the waxy extract. Kinetic analysis of the in vitro release data of the formulations showed that the best-fit drug release model varied with the drug:propolis extract ratio of the formulations. Conclusion: Formulation F13 (with equal proportion of drug and bee glue extract) came out best from the dissolution test for indomethacin extended-release capsules as it exhibited zero order kinetics. This fpormulation is therefore suitable for further development as a matrix formulation for controlled release.