A Novel Stability Indicating Method Development and Validation for Simultaneous Estimation of Oxcarbazepine and Olanzapine by RP-HPLC in Pharmaceutical Dosage Form

A novel stability-indicating RP-HPLC method was developed and validated for the simultaneous estimation of Oxcarbazepine and Olanzapine in pharmaceutical dosage forms. The method utilized a Waters X-Terra RP-18 column with a mobile phase composition of acetonitrile and 0.1% triethylamine (30:70), pH adjusted to 2.5 using orthophosphoric acid. The flow rate was maintained at 1 mL/min, and detection was carried out at 272 nm. The method demonstrated excellent linearity for Oxcarbazepine (37.50–225.00 µg/mL, R² = 0.99989) and Olanzapine (5.00–30.00 µg/mL, R² = 0.99973), along with high precision and accuracy (%RSD < 1.0). Robustness was confirmed under varied conditions, and forced degradation studies validated the method's specificity, with no significant interference from degradants. The proposed method is reliable, reproducible, and suitable for routine analysis of Oxcarbazepine and Olanzapine in combined dosage forms.