Two Wavelength Method for Estimation of Risperidone and Trihexyphenidyl HCl in Combined Tablet Dosage Form

No one UV Spectrophotometric method is available for simultaneous estimation of Risperidone (RIS) and Trihexyphenidyl HCL (THP). The objective of present work is to develop a new, simple, accurate and sensitive UVspectrophotometric two wavelength method for simultaneous determination of RIS and THP in combined pharmaceutical dosage form. Two wavelength i,e 238 nm and 271 nm were selected for estimation of RIS where as wavelength 217 nm was selected for estimation of THP using 0.1 N HCL solution as solvent. RIS and THP shows linearity in the concentration range of 0–40 μg/ml and 0–80 μg/ml respectively. The method was validated statistically.