Merits of Water-Soluble Polymers

In aqueous media diverse dynamic polymeric networks and assemblies have been developed using the inclusion complex-forming competency of CDs as a noncovalent binding motif. These polymeric systems have been explored for biomedical applications like sustained and targeted release of APIs, medical diagnostics and tissue engineering (biocompatible scaffolds). 

The use of water-soluble polymers in ternary CD complexes has also been utilized for controlling the rate of release of drug from cyclodextrin formulation. It seems that ternary complexes consisting of polymers as ternary component with low viscosity (PVP) tend to dissolve rapidly [25], while polymers with matrix-forming property (HPMC) lead to sustained drug release [26] in comparison to corresponding binary systems. 

The synergistic effect on solubility of complexes and complexation efficiency by the addition of small amounts of water-soluble polymers has been reported by various authors. In the case of complexation of ionizable drugs with cyclodextrins, pH adjustments have to be done [27-29] to increase the intrinsic solubility of drug, which consequently leads to enhanced CD solubilization of drug [30]. Stability constant of such ionized drug-cyclodextrin system can also be increased by addition of water-soluble polymers, which results in enhanced drug solubilization [31]. 

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