Spectrofluorimetric Method for the Determination of Doxepin Hydrochloride in Commercial Dosage Forms

A novel spectrofluorimetric method has been developed for the determination of doxepin hydrochloride in commercial dosage forms. The method is based on the fluorescent ion pair complex formation of the drug with eosin Y in the presence of sodium acetate-acetic acid buffer solution of pH 4.52 which is extractable in dichloromethane. The extracted complex showed fluorescence intensity at lambda(em) = 567 nm after excitation at 464 nm. The calibration curve was linear over the working range of 0.1-0.8 A mu g ml(-1). Under the optimized experimental conditions, present method is validated as per International Conference on Harmonization guidelines. The limit of detection for the developed method is 2.95 ng ml(-1). The method has been successfully applied to the determination of doxepin hydrochloride in commercial dosage forms. The results are compared with the reference spectrofluorimetric method.