EFFECT OF POROUS SILICA ON THE RHEOLOGY OF OINTMENTS OF FLURBIPROFEN AND ITS RELEASE

The physicochemical properties of flurbiprofen in its physical and gro und mixtures with porous silica were studied by differential scanning calorimetry, powder X-ray diffraction and infrared spectroscopy. Grind ing of the mixtures of porous silica and flurbiprofen resulted in its transformation to the amorphous ionic state. The pure drug and its phy sical and ground mixtures with Florite were incorporated into differen t ointment bases. The release of the drug was found to be dependent on the type of ointment base. Use of the ground mixtures resulted in enh anced drug release from an oleaginous base but decreased the drug rele ase from emulsion bases. Rheological studies were carried out on vario us ointment bases. A good correlation was found between the release of the drug and the effect of Florite on the viscosity of the different ointment bases.