Abstract: 22 factorial design statistical model was applied in formulation development and processing conditions for Paracetamol (PCT) effervescent and non effervescent granules. Solid dispersion of PCT with PEG 6000 in the ratio 1:0.5 was prepared to increase the aqueous solubility of the drug and hence the drug release for dispersible effervescent granules. In the formulation of dispersible effervescent granules of PCT, in vitro effervescence time was the dependent variable (maximum up to 2 minutes) and the concentrations of two effervescent agents were the two independent variables chosen at two different levels. In the formulation of non effervescent granules of PCT angle of repose was the dependent variable (with excellent flow) and the concentration of binder and lubricant were the two independent variables chosen at two different levels. Using polynomial equation Y= B0 + B1X1 + B2X2 + B12X1X2, three new formulations were chosen and performed to evaluate experimental and predicted responses. A good correlation was obtained between the experimental and the predicted values for non effervescent granules but the same was not for dispersible effervescent granules because a stoichiometry exists between the effervescent agents for effervescence to occur.

 
Introduction: 1,2,3 In formulation and process development, one of the two basic approaches is adopted which includes randomized approach (or experimentation) and factorial design (optimization). The randomized approach is time consuming, unreliable, costly and often unsuccessful whereas factorial design is a useful tool since various independent variables at different levels are evaluated against dependent variables to obtain maximum information in minimum number of runs and hence it is efficient and economical.
The aim of the present work was to observe the application and practicality of statistical model like 22 factorial design in formulation development and processing conditions at undergraduate level for process and formulation variables. A representative example of process variable was formulated as non-effervescent granules of Paracetamol (PCT) and that of pharmaceutical formulation variable was formulated as dispersible effervescent granules of PCT for paediatric use. Paracetamol (PCT), an analgesic and antipyretic agent with weak anti-inflammatory activity has a paediatric dose of 120 – 250 mg orally. It is slightly soluble water and hence solid dispersion was made to increase the solubility in the effervescent granules to be added to water during administration.