Development and Validation of RP-HPLC Method for Simultaneous Estimation of Haloperidol and Trihexyphenidyl Hydrochloride in Tablet Dosage Form

Haloperidol is a common antipsychotic drug used to treat schizophrenia, and Trihexyphenidyl hydrochloride is an antiparkinsonian medication. The combination formulation is used to treat schizophrenia as well as depression. A simple, accurate, and precise assay as well as a rapid stability-indicating reversed-phase high performance liquid chromatography (RP-HPLC) method for the simultaneous estimation of Haloperidol (HAL) and Trihexyphenidyl hydrochloride (THP) from their combination drug product have been developed and validated. The proposed method is based on reversed-phase separation of the two drugs using a Zorbax Eclipse XDB C18 column (150 mm x 4.6 mm, 5 um) kept at 30°C. The optimal mobile phase was composed of 0.5 mL triethylamine 0.05 M phosphate buffer having pH 3.75: acetonitrile: (65:35 v/v), a flow rate of 1.2 mL.min-1, and PDA detection at 210 nm. The method was validated in accordance with ICH standards. It was found to be precise and reproducible. Linearity was achieved in the concentration ranges of 6-60 ug mL-1 for HAL and 8-80 ug mL-1 for THP, with correlation coefficients of 0.999 and 1.000, respectively. The mean percent recovery of triplicate samples at each level for both drugs was 99.10-100.7% for Haloperidol and 98.7-100.6% for Trihexyphenidyl hydrochloride. The proposed method can be used to successfully test quality control and stability samples from bulk manufacturing and pharmaceutical dosage forms.