Formulation Development and Evaluation of Sustained Release Matrix Tablets of Guaiphenesin

Abstract

In this study we sought to formulate and evaluate sustained release matrix tablet of guaiphenesin by melt granulation technology. The sustained release tablets were prepared by melt granulation technique using rice bran wax as a drug retardant and dibasic calcium phosphate (DCP) as a channelling agent. Guaiphenesin is an expectorant and has a short plasma half-life of one hour. Because of high frequency of administration and short biological half-life, guaiphenesin was considered as model drug. Sustained release formulation that would maintain plasma levels for 12 hours is sufficient for twice daily dosing of guaiphenesin. The compatibility of drug and wax was examined by differential scanning calorimetry (DSC). The effect of waxes at different (drug: wax) concentrations on the release profile of drug from matrix formulation were studied. Drug release was studied at pH 1.2 for 2 hour and pH 6.8 for 10 hours. A significant retardation in the drug release was observed by increasing the wax concentration. The drug release study revealed that wax concentration of 30% to be optimum. Dissolution study showed 99% drug release within 12 hrs. Kinetic modelling of in vitro dissolution profiles revealed the drug release mechanism ranges from diffusion controlled or Fickian transport to anomalous type or non-Fickian transport. These results suggest that the rice bran wax has good release retardant property for highly water-soluble drug such as guaiphenesin.