The Effect of Formulation Variables on the Release Kinetics of Paracetamol Tablet Formulations.

Aim: The objective of this work was to study the effects of formulation variables on the release kinetics of paracetamol tablet formulation. Materials and Methods: Paracetamol tablets were formulated using wet granulation (WG) and direct compression (DC) using two predetermined pressures. Avicel, dicalcium phosphate (DCP) and pregelatinized starch (PGS) were used as directly compressible excipients for the DC method while corn starch, gelatin and acacia were used as binders for the WG methods. Tensile strength (TS) and the dissolution times of the tablets were determined. The drug release data were fitted into different kinetic models to determine the drug release mechanism(s) for the paracetamol tablets. Noyes-Whitney plots were further used to obtain release processes for formulations having r2 of best fit from kinetic modeling. Results and Discussion: The TS and dissolution times increased with increase in compressional pressure for all tablet formulations. The ranking of TS for tablets was starch > gelatin > acacia > avicel > DCP > PGS. Drug release kinetics indicated that the drug release was best explained by first order model for direct compression formulation. However, first-order and Higuchi equations gave the best fit with the highest correlation coefficient for the formulation prepared through wet granulation. Korsmeyer’s plots indicated an n value ranging from 1.227 to 1.839 which indicates that the drug release mechanism from the formulations was by super case II transport. Generally, r2 values were higher for tablets with lower compression pressures and higher for those with binders than direct compression excipients. Conclusion: The release kinetics of paracetamol tablets were observed to be influenced by the interplay of variables involved like compressional pressure, formulation excipient and method. Wet granulation was also found to produce optimum release than direct compression. Keywords: Paracetamol tablets, Release kinetics, Compression pressure, Formulation methods, Formulation excipients.