Controlled release of ranitidine from conductive polypyrrole films

Sa？etak Incorporation and controlled release of active substances from the conductive polypyrrole films by electric stimulation were investigated. Change of the redox state of the conductive polymer was induced by this stimulation, which allowed the incorporation and release of the drug at different rates. Polymerization of pyrrol on a stainless steel substrate was performed by cycling the potential 40 times in predetermined potential window, after which uniform polymeric film was formed and used as a medium for incorporation and release of the active substance. Stability of obtained films, as well as the electrochemical behaviour of ranitidine hydrochloride was investigated by cycling the potential of the film electrode in 0.9 % NaCl in the same potential window used for the polymerization. Uptake and release of the active substance was performed at constant potential and monitored by chronoamperometry. Although incorporation of the ranitidine hydrochloride was not obvious from the measured infrared spectra, incorporation and release was confirmed and quantified by monitoring the concentration of the active substance in the electrolyte. It was determined that maximum reversible uptake was 351 μg cm-2. However, successive potential stimuli did not result in the equal released quantity, as expected for the ideal controlled-release system based on conducting polymers