Development and validation of an analytical method for the stability of duloxetine hydrochloride

The objective of the study was to develop and validate an analytical method for estimating the stability of duloxetine hydrochloride. The drug was subjected to the stress conditions prescribed by the International Conference on Harmonization, including hydrolysis, oxidation, photolysis and dry heat. Five degradation products were formed, which were separated by high-performance liquid chromatography on a Kromasil C18 (150 mm × 4.6 mm, 5 μm) column in a gradient elution programme. The flow rate was 1 ml/min, and the detection wavelength was set to 225 nm. The retention time of the drug was 35.7 min, and analysis was completed within 40 min. The method was validated with respect to linearity, precision, accuracy, robustness and limits of detection and quantification as per the International Conference on Harmonization. The results were linear (r2 = 0.999) over the range 50–400 μg/ml and accurate over the range 99.41–102.98. The method was robust and rugged, as there was insignificant variation in the results of analysis with changes in flow rate and temperature separately.