Study on Mixed Solvency Concept in Formulation Development of Aqueous Injection of Poorly Water Soluble Drug

In the present investigation, mixed-solvency approach has been applied for the enhancement of aqueous solubility of a poorly water- soluble drug, zaltoprofen (selected as a model drug), by making blends (keeping total concentrations 40% w/v, constant) of selected water-soluble substances from among the hydrotropes (urea, sodium benzoate, sodium citrate, nicotinamide); water-soluble solids (PEG-4000, PEG-6000); and co-solvents (propylene glycol, glycerine, PEG-200, PEG-400, PEG-600). Aqueous solubility of drug in case of selected blends (12 blends) ranged from 9.091 ± 0.011 mg/ml–43.055 ± 0.14 mg/ml (as compared to the solubility in distilled water 0.072 ± 0.012 mg/ml). The enhancement in the solubility of drug in a mixed solvent containing 10% sodium citrate, 5% sodium benzoate and 25 % S cosolvent (25% S cosolvent contains PEG200, PEG 400, PEG600, Glycerine and Propylene glycol) was more than 600 fold. This proved a synergistic enhancement in solubility of a poorly water-soluble drug due to mixed cosolvent effect. Each solubilized product was characterized by ultraviolet and infrared techniques. Various properties of solution such as pH, viscosity, specific gravity and surface tension were studied. The developed formulation was studied for physical and chemical stability. This mixed solvency shall prove definitely a boon for pharmaceutical industries for the development of dosage form of poorly water soluble drugs.