Box–Behnken Design Used to Optimize the Simultaneous Quantification of Amitriptyline and Propranolol in Tablet Dosages by RP-HPLC-DAD Method and Their Stability Tests

This study’s goal is to use a Box–Behnken design [BBD] methodology to create a new reverse-phase high-performance liquid chromatography diode-array detection [RP-HPLC-DAD] method for the simultaneous quantification of Amitriptyline and Propranolol in tablet dosages. The amitriptyline and propranolol standard drug peaks were obtained using a C-18 column with a dimension of 4.6 × 100 mm and a particle size packing of 2.5 µm at the retention time of 5.328 and 7.48 min, respectively. The mobile phase composition was a 75:25 mixture of methanol and 0.1 percent orthophosphoric acid, flowing at 1.0 mL/min at 26 °C. The peaks were identified at 257 nm after injecting 20 µL of the sample. An assay of the marketed tablets was performed, and the result was 101.33 and 99.4% for amitriptyline and propranolol, respectively, when compared to the standard calibration curve. Forced degradation investigations, such as acid, base, H₂O₂, and neutral condition, were performed. The results for both medications in term of % degradation were as follows: amitriptyline (16.07, 91.92, 26.98, and 0.64) and propranolol (15.84, 11.52, 9.09, and 3.62). According to the ICH criteria, the findings of the validation parameters were within an acceptable range. The new RP-HPLC-DAD method with BBD application is easy, accurate, and time-saving.