This paper reviews the application of intrinsically conducting polymers (ICPs) in drug delivery. ICPs are organic polymers with electrical, magnetic and optical properties usually associated with metals, whilst retaining the advantageous mechanical properties and ease of processing usually associated with polymers. Due to the inherent properties of these unique materials, electrical stimulation can be used to alter the redox state of ICPs, which in turn can modify the release rate of drug. The controlled release of drugs from ICPs has been reported in the literature since the 1980s. Following continued development, clinical applications of ICP-based drug delivery systems (DDS) have been reported recently. The next generation of controlled release technologies could utilise the biosensing properties of ICPs combined with their drug delivering abilities to develop an intelligent drug delivery system from a single material where the release rate of drug self adjusts in response to a sensed change in local body environment. This article provides an overview of ICP synthesis and properties relevant to their use as DDS, including biodegradability and biocompatibility, followed by literature on ICP-based DDS examining different methods of drug incorporation and release. The pharmaceutical applications of these systems have also been discussed. It is concluded that ICPs hold great promise in drug delivering implants where the dose can be adjusted through application of external stimulus, thus optimising benefit to side effect ratio while simultaneously ensuring patient adherence.
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