Simultaneous spectrophotometric estimation of haloperidol and trihexyphenidyl in tablets

The combination of haloperidol and trihexyphenidyl is a dosage form to be used as antidyskinetic agent. Literature revealed that there is no single method for the simultaneous estimation of these drugs in tablet dosage form, which prompted us to develop a simple, rapid, accurate, economical and sensitive spectrophotometric method. The simultaneous estimation method is based on the principle of additivity of absorbance, for the determination of haloperidol and trihexyphenidyl in tablet formulation. The absorption maxima of the drugs were found to be at 245.0 nm and 206.0 nm respectively for haloperidol and trihexyphenidyl in methanol and 0.1N HCl (90:10). The obeyance of Beer Lambert's law was observed in the concentration range of 2.5-12.5 µg/ml for haloperidol and 1.0-5.0 µg/ml for trihexyphenidyl. The accuracy and reproducibility of the proposed method was statistically validated by recovery studies.