Compatibility Studies of Valsartan with Different Pharmaceutical Excipients

Compatibility studies between active drugs and excipients are substantial in the pharmaceutical technology. Thermal analysis has been extensively used to obtain information about drug-excipient interactions and to perform pre-formulation studies of pharmaceutical dosage forms. The objective of the present study was to evaluate the compatibility of the valsartan (VALS) with pharmaceutical excipients of common use including diluents, binders, disintegrants, lubricants and solubilising agents. Thermogravimetry (TG), derivative thermogravimetry (DTG), but especially differential scanning calorimetry (DSC) were used for a first screening to find small variations in peak temperature and/or their associated enthalpy for six drug/excipient mixtures (starch, cross caramelose sodique, microcrystalline cellulose 102, povidone K30, lactose monohydrate and magnesium stearate), which indicate some degree of interaction. Additional methods using Fourier transformed infrared spectroscopy (FT-IR) and X-ray powder diffraction (XRPD) confirmed the incompatibility of VALS with starch, povidone K30, lactose monohydrate and magnesium stearate. Those excipients should be avoided in the development of solid dosage forms.