Development and Validation of Rp-HPLC Method for Atomoxetine Hydrochloride and Sodium Benzoate in Pharmaceutical Dosage Form

A simple, precise, and stability-indicating reversed-phase high-performance liquid chromatographic (RP-HPLC) method was developed and validated for the simultaneous estimation of Atomoxetine Hydrochloride and Sodium Benzoate in pharmaceutical oral liquid dosage form. Chromatographic separation was achieved on an Intersil ODS-3 column (150 x 4.6 mm, 5 um) using a gradient elution programme with Mobile Phase A (phosphate buffer, pH 3.0 +/- 0.05) and Mobile Phase B (buffer: methanol, 20: 80 v/v) at a flow rate of 1.0 mL/minute, with detection at 270 nm and a total run time of 25 minutes. Atomoxetine Hydrochloride and Sodium Benzoate eluted at approximately 12.4 minutes and 5.3 minutes, respectively. The method was validated as per ICH Q2(R1) guidelines for specificity, linearity, accuracy, precision, limit of detection (LOD), limit of quantification (LOQ), and robustness. The method showed excellent linearity over the range of 575-1725 ug/mL for Atomoxetine Hydrochloride (r = 0.999) and 100-300 ug/mL for Sodium Benzoate (r = 0.9999). Percentage recovery for both analytes was within 98.0-102.0%, and the relative standard deviation (%RSD) for precision studies was below 2.0% at every level. As no official pharmacopoeial method currently exists for the simultaneous estimation of Atomoxetine Hydrochloride with Sodium Benzoate preservative, the proposed method is recommended for routine quality control analysis of this combination in pharmaceutical dosage forms.