Development and Validation of High Performance Liquid Chromatographic Method for Simultaneous Estimation of Risperidone and Trihexyphenidyl in Combined Dosage form

A simple, rapid, accurate, precise and reproducible reverse phase high performance liquid chromatographic method has been developed for the estimation of Risperidone and Trihexyphenidyl hydrochloride was determined using reversed-phase liquid chromatography method using ODS Hypersil C18 column (250 mm × 4.6 mm id, 5μm as a stationary Phase and Methanol : Acetonitrile : Acetate Buffer (pH 4.0) (70 : 20 : 10, v/v/v) as a mobile phase pumped at a flow rate of 1.0 ml/min. Quantification was achieved with ultraviolet detection at 214 nm over concentration ranges of 2-20 μg/ml for Risperidone and 1-10 μg/ml for Trihexyphenidyl hydrochloride with mean accuracy 101.02 ± 0.19 and 101.3 ± 0.38 %, for Risperidone & Trihexyphenidyl hydrochloride respectively. The method was successively applied to tablet dosage forms as no chromatographic interferences from the tablet excipients were observed. The method retained its accuracy and precision when the standard addition technique was applied.