Absorption Ratio Method for Simultaneous Estimation of Haloperidol and Trihexyphenidyl in Tablet

A simple, accurate, economical and reproducible procedure for simultaneous estimation of haloperidol (HP) and trihexyphenidyl (THP) in their tablet dosage form is described. The method involves absorbance measurement at 218.8 nm (isobestic point) and 245.0 nm (λ_max of haloperidol), in methanol and 0.1N HCl (90:10). Both the drugs obey Beer Lambert's law in the concentration range of 2.5–12.5 μg/ml (HP) and 1.0–5.0 μg/ml (THP). The results of analysis have been validated statistically and by recovery studies.