Development and validation of a stability-indicating LC method for determining palonosetron hydrochloride, its related compounds and degradation products using naphthalethyl stationary phase

A selective and simple reversed phase HPLC method using naphthalethyl stationary phase was developed and validated for the quantitative determination of palonosetron hydrochloride (PALO), its related compounds and degradation products. Chromatographic separation (R(s)>2) was achieved with linear gradient mode of elution at a flow rate of 1 mL/min and with UV detection at 210 nm. The intra and inter-day coefficients of variation were less than 1.0% (RSD). Consistent recoveries were obtained for PALO (99.2-100.5%) and its impurities (90.0-104.8%). All the analytes exhibited excellent linearity with R² value greater than 0.998. Limit of detection (LOD) and limit of quantification (LOQ) were determined to be in the range 0.011-0.013 μg/mL and 0.035-0.046 μg/mL respectively. The test solution was found to be stable up to 5 days. Induced degradation methods were applied to study the degradation behavior of the drug. LC-MS was used to analyze the degraded samples and possible structural identifications were assigned based upon known reactivity of the drug and molecular weights. The m/z values matched with the hydroxylated, keto and N-oxide metabolites of PALO. The stress samples were assayed against a qualified reference standard and the mass balance was found close to 99.9%.