Electrically credible polymer gel for controlled release of drugs

NEW controlled drug-delivery systems are being explored to overcome the disadvantages of conventional dosage forms¹. For example, stimulated drug-delivery has been used to overcome the tolerance problems that occur with a constant delivery rate, to mimic the physiological pattern of hormonal concentration and to supply drugs on demand^1,2. Stimuli-sensitive polymers, which are potentially useful for pulsed drug delivery, experience changes in either their structure or their chemical properties in response to changes in environmental conditions². Environmental stimuli include temperature^3,4, pH^5,6, light (ultraviolet⁷ or visible⁸), electric field^9-12 or certain chemicals¹³. Volume changes of stimuli-sensitive gel networks are particularly responsive to external stimuli, but swelling is slow to occur^14,15. As well as being useful in the controlled release of drugs, such systems also provide insight into intermolecular interactions¹⁶. Here we report on a novel polymeric system, which rapidly changes from a solid state to solution in response to small electric currents, by disintegration of the solid polymer complex into two water-soluble polymers. We show that the modulated release of insulin, and by extension other macromolecules, can be achieved with this polymeric system.