Co-Crystals of Valsartan: Preparation and Characterization

Author(s): Raju Thenge*, Rakesh Patel, Nandu Kayande and Nilesh Mahajan

Abstract: Valsartan is an angiotensin II receptor antagonist effectively used in the management of hypertension. Valsartan has poor solubility and dissolution rate which leads to the poor a bioavailability (about 23%). Thus an attempt was made to prepare Co-crystals of Valsartan with different coformer to improve the solubility and dissolution rate. The valsartan Co-crystals using coformer such as succinic acid, fumaric acid and oxalic acid was prepared by Solvent evaporation method. The prepared Valsartan Co-crystals were evaluated for saturation solubility, dissolution rate and micromeritic studies. The Valsartan Co-crystals were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), X-Ray Diffraction (X-RD) and Scanning Electron Microscopy (SEM). The solubility and dissolution rate of Valsartan Co-crystals was significantly improved compare with the pure valsartan. The melting point of Valsartan cocrystals was shifted to lower temperature supports the solubility enhancement. The Valsartan cocrystals showed improvement in the flow properties which was helpful during the compression of cocrystals into the tablet. The FT-IR data showed the slight shifting of the peaks in the co-crystals spectra which supports the formation of new solid phase. The DSC spectra indicate the slight decrease in the melting point of Valsartan cocrystals compare to pure valsartan. The crystallinity of the cocrystas was decrease in the Co-crystals due to lattice arrangement between Valsartan and Coformer. The SEM photomicrograph showed difference in the habit of Valsartan co-crystals and the pure valsartan. Thus Cocrystals techniques was successfully employed in the solubility and dissolution rate enhancement of Valsartan.

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