Karaya and ghatti gum as a novel polymer blend in preparation of extended release tablets: optimization by factorial design

The objective of the study was to formulate sustained release matrix tablets of diclofenac sodium using karaya and ghatti gum as the matrix polymers. 32 full factorial design was employed to optimize the drug release profile systematically. Matrix tablets were prepared by the wet granulation technique. The dependent variables selected were, % of drug released in first hour (Y1), % of drug released in 12 h (Y2) , diffusion exponent (n) (Y3) and time taken for the 50 % of the drug release (T50%) (Y4). The independent variables are amount of karaya (X1) and gatti gum (X2). The FTIR and DSC studies confirmed the drug-polymer compatibility and the pre-compression granular properties were assessed indicating a good flow property. The results of evaluation of the tablets were found to be within the standard limits indicating pharmaco-technical characteristics. The response variables studied were found as follows: Y1 ranged between 2.57 to 26.74 %, Y2 was found to be between 61.87 to 101.982 %, Y3 ranged between 0.45 to 1.26 and Y4 ranging between 3.98 to 9.56 h, respectively, for all batches. The release data showed a good fit in zero order, Higuchi & Peppa’s equation with high R2 value. The best fit was Peppa’s model. It was observed that the rate of swelling and erosion was found to compliment the drug release kinetics which was further confirmed by SEM studies. The experimental values were in close agreement with the predicted response, indicating adequate fitting and validation of formula generated by constrained optimization. Results of the stability studies showed no significant changes in drug content, physical appearance or the dissolution profile of the prepared tablets. Thus, the experimental results obtained indicated that the feasibility of the blend of two gums can be used efficiently in order to formulate a sustained release tablet without any lag effect.