Application of response surface methodology to formulation of ionotropically gelled gum cordia/gellan beads

In the present study, metformin-loaded gum cordia/gellan beads were prepared employing ionic-gelation technique. The formulation of sustained release beads was optimized using response surface methodology. Effect of various formulation and process variables on %entrapment and %release was screened employing Plackett-Burman screening design. The results revealed that concentrations of drug and calcium chloride, hardening time and temperature exerted significant effect. Additional batches of beads were prepared utilizing central-composite design for estimating extending effect in a spherical domain. A second-order polynomial equation fitted to the data was used to predict the responses in the optimal region. The optimized formulation provided %entrapment and %release, which were close to the predicted values. The proposed mathematical model is found to be robust and accurate for optimization of controlled release beads of metformin hydrochloride, consistent with the goals of adequate %entrapment and more than 80% release in 24 h.