Design and Characterization of Valsartan Co-Crystals to Improve its Aqueous Solubility and Dissolution Behavior

The aim of the work was to prepare co-crystals of valsartan, a BCS Class II drug to enhance its aqueous solubility and bioavailability. The solvent evaporation method was used to prepare co-crystals by using different co-formers and varying the drug to co-former molar ratios. Succinic acid was found to be suitable co-former to prepare co-crystals with good physico-chemical properties. The solid state characterization of co-crystals were studied by FTIR, DSC and XRD. The co-crystals were evaluated for the saturation solubility and dissolution studies. Solubility study in distilled water indicated low solubility of valsartan (198.5 μg/ml), there was 2.6 fold increase in the solubility of co-crystals prepared using succinic acid, with 1:5 drug to co-former ratio (520.6 μg/ml). Solid state characterizations indicated there was no change in the chemical nature of the co-crystals compared to pure drug. Presence of crystalline co-former induced crystallinity to the developed co-crystals. Thus developed co-crystals were found to be suitable alternative to increase the solubility and dissolution rate of valsartan.