The effect of water-soluble polymers on aqueous, solubility of drugs

The effect of three water-soluble polymers, i.e., hydroxypropyl methylcellulose and polyvinylpyrrolidone, on the aqueous solubility of drugs was investigated. Addition of a small amount, i.e., 0.10-0.25% (w/v>, of the polymers results in significant enhancement of the aqueous solubility. The solubility studies indicate that a large fraction, e.g., 30-50%, of drug molecules in dilute aqueous polymer solutions is bound to the polymers. This polymer drug binding will affect the physicochemical properties and the availability of drugs in aqueous drug formulations containing water-soluble polymers.