Simultaneous estimation of naltrexone hydrochloride and zonisamide in synthetic mixture by RP-HPLC method

A simple, rapid, precise, and reproducible RP-HPLC method development and validation done for simultaneous estimation of Naltrexone Hydrochloride and Zonisamide in synthetic mixture. The isocratic method was developed using a Water Symmetry C18 (250 mm × 4.6 mm, 5 μm) column. Mobile phase composition was Phosphate Buffer: Methanol (75:25 %V/V) (Buffer-1.36 g of KH₂PO₄ in 1000 ml adjust pH 3.0 ± 0.05 with OPA.), flow rate 1 ml/min and detection carried out at 230 nm at column temperature 30°C. The injection volume was 10μl with run time of 10 minutes. Parameters such as linearity, precision, accuracy, recovery, specificity and robustness are performed as per ICH guidelines Q2(R1). Retention time of Naltrexone Hydrochloride and Zonisamide were found to be 3.92 min and 8.15 min respectively. The developed method found linear in the range of 1-10 μg/ml for Naltrexone Hydrochloride and 2.84-142 μg/ml for Zonisamide (R² = 0.9999 for both drugs). The % Recovery were found to be 99.39 %-100.70 % and 98.91 %-100.59 % for Naltrexone Hydrochloride and Zonisamide respectively. The RSD for both drug were less than 2 for precision, specificity and robustness.