Assay of Dicyclomine Hydrochloride in Pharmaceutical Formulations by Extractive Spectrophotometry

Four simple and sensitive extractive spectrophotometric methods have been described for the assay of dicyclomine hydrochloride either in pure form or in pharmaceutical formulations. The developed methods involve formation of coloured chloroform extractable ion-pair complexes of the drug with tropaeolin oo (TPoo) (Method-A), bromothymol blue (BTB), bromocresol green (BCG) and bromophenol blue (BPB) (Method-B) in acidic medium. The extracted complexes showed absorbance maxima in the range 410-415 nm for all four methods. Beer’s law is obeyed in the concentration ranges 1.25-25, 2.0-25, 2.5-25 and 2.5-25 μg/mL with TPoo, BTB, BCG and BPB, respectively. The effect of concentration of dye, pH, and interference of excipients have been studied and optimized. The limits of detection and quantification have been determined for methods. All the four methods have been validated as per the guidelines of ICH. The methods have been applied to the determination of drug in commercial tablets and results of analysis were validated statistically through recovery studies.