Characterization of forced degradation products of Netarsudil: Optimization and validation of stability-indicating RP-HPLC method for simultaneous quantification of process related impurities of Netarsudil

INTRODUCTION: This study reports the resolution, identification and characterization of forced degradation products of netarsudil by liquid chromatography-tandem mass spectrometry by validating a simple and sensitive HPLC method for resolution, identification and quantification of two process related impurities in netarsudil
METHODS: The chromatographic separation was accomplished on an ZORBAX Eclipse XDB C18 (250×4.6 mm; 5 µ id) column at room temperature as stationary phase and 257 nm as detector wavelength with the mobile phase consisting of acetonitrile, methanol and pH 4.6 phosphate buffer in 45: 35: 20 (v/v) at 1.0 mL/min flow rate in isocratic elution.
RESULTS: The method reports very sensitive detection limit of 0.008 µg/mL for impurity 1 and 0.003 µg/mL for impurity 1. The method produces calibration curve linear in the concentration level of 25 -200 for netarsudil and 0.025 - 0.2 µg/mL for impurities. The proposed method gives acceptable results for other validation parameters such as accuracy, precision, ruggedness and robustness. The drug was subjected to various stress conditions such as acid, base, peroxide, thermal and UV light to investigate the stabilityindicating ability of the method. Considerable degradation was observed in stress studies and the degradation products were well resolved from its process related impurities. The characterization of degradation products was performed based on collision induced dissociation mass spectral data and the possible structures of the six degradation compounds of netarsudil were proposed.
DISCUSSION AND CONCLUSION: The outcomes of other validation studies were likewise satisfactory and proven adequate for regular analysis of netarsudil and its process related impurities in bulk drug and pharmaceutical dosage forms and can also applicable for evaluation of stress degradation mechanism of netarsudil