A stability indicating HPLC method for the determination of electrochemically controlled release of risperidone

A rapid stability indicating reversed-phase high-performance liquid chromatography (HPLC) method is developed for the determination of the electrochemically controlled risperidone release from a novel drug delivery system, based on the intrinsically conducting polymer (ICP), polypyrrole. The chromatographic separation was carried out on a C(18) column using acetonitrile-potassium dihydrogen phosphate (45:55, v/v, pH 6.5; 0.05 M) as the mobile phase. The isocratic flow is at 1.0 mL/min, with a runtime of 6 min, and the UV detection is at 237 nm. This provided a calibration curve linear over the range of 1-100 μg/mL. Intra-day and inter-day accuracy range between 98.4% and 102.6%, and the RSD for precision is <1.43%. The limit of detection and quantitation were determined to be 0.001 μg/mL and 0.01 μg/mL, respectively. The analytical method confirmed risperidone is stable for the oxidizing electric potential and the acidic environment involved during the manufacture and operation of the novel drug delivery system. The rate of risperidone release from polypyrrole depended on electrical stimulation applied to the polymer. This HPLC method is significantly faster than previously published methods and is the first to investigate the effect of an oxidizing potential on risperidone stability, which is essential for the evaluation of controlled delivery from an ICP-based system.