Development and Validation of Stability Indicating RP-HPLC Method for Simultaneous Estimation of Imipramine Hydrochloride and Diazepam in Combined Pharmaceutical Dosage Form

A simple, precise, and stability indicating high performance liquid chromatography (HPLC) method was developed and validated for the simultaneous determination of Imipramine hydrochloride and Diazepam in pharmaceutical dosage form. Materials and Methods: The method involves the use of easily available inexpensive laboratory reagents. The separation was achieved on Phenomenex Prodigy C-18 column (150*4.6 mm, i.d., 5 ?m particle size) with isocratic flow with UV detector. The mobile phase at a flow rate of 1.0 mL/min consisted of methanol and 0.1%v/v ortho phosphoric acid (pH 3) in the ratio of 70:30 v/v. Results: A linear response was observed over the concentration range 5.00-50.00 ?g/mL of diazepam and the concentration range 5.00-50.00 ?g/mL of Imipramine HCl. Limit of detection and limit of quantitation for Imipramine were 2.73 ?g/mL and 1.27 ?g/mL, and for Diazepam were 1.80 ?g/mL and 1.98 ?g/mL, respectively. The method was successfully validated in accordance to ICH guidelines acceptance criteria for linearity, accuracy, precision, specificity, robustness. Conclusion: The analysis concluded that the method was selective for simultaneous estimation of Imipramine HCl and Diazepam can be potentially used for the estimation of these drugs in combined dosage form