Drug release from tableted wet granulations comprising cellulosic (HPMC or HPC) and hydrophobic component

The effects of component nature, proportion and processing on the release rate and mechanism were investigated for tablets comprising drug, cellulosic polymer and hydrophobic components. Four drugs differing in solubility (diclofenac sodium, ibuprofen, naproxen and indomethacin), two cellulosic polymers (HPC and HPMC) and hydrophobic Emvelop® were used in two levels of mass fraction and weight ratio of drug:carrier and of cellulosic-hydrophobic component. Compression was applied after granulation or physical mixing. Drug release was evaluated in pH 6.5 phosphate buffer BP and elucidation of the release mechanism was attempted by fitting kinetic models. Statistical significance of the effects of formulation variables on the release rate and mechanism expressed by the coefficient, k, and exponent, n, of the power law kinetic model, respectively, was evaluated by ANOVA. It was found that for the release mechanism most significant is the effect of drug solubility followed by cellulosic polymer type, mixing procedure and drug mass fraction. Significant interaction between drug solubility and type of cellulosic polymer indicated that alteration in the swelling of HPMC and HPC is caused by the drug solubility. Weight ratio of cellulosic-hydrophobic component does not affect the release mechanism, but only the release rate. Similarly, for the release rate most significant was found the effect of drug solubility, followed by cellulosic polymer type, weight ratio of cellulosic-hydrophobic component, mixing method and drug mass fraction. Also significant were the interactions of drug solubility with the type and proportion of the cellulosic polymer and the processing applied. Depending on the drug solubility and type of polymer present, wet granulation can increase or decrease the release rate.