Development and validation of a rapid HPLC-UV method for simultaneous quantification of apomorphine and related impurities in drug products

Apomorphine, a potent dopamine agonist, plays a significant role in the management of advanced Parkinson's disease, and requires careful monitoring of the drug and its impurities for safety and efficacy. The USP monograph for Apomorphine Hydrochloride currently uses classical methods—titrimetry for assay and Thin-Layer Chromatography (TLC) for impurity testing—which, although effective, are not comparable in accuracy and speed to newer chromatographic techniques like High-Performance Liquid Chromatography (HPLC). For this, an HPLC method was developed using a C18 column, which possesses hydrophobic interaction capacity, and an isocratic elution mode with a mobile phase of 10 mM phosphate buffer (pH 3.0) and methanol (87.5:12.5) containing 0.075% L-tartaric acid. This combination allowed efficient separation of apomorphine from impurities without compromising stability.The method was thoroughly validated according to International Council for Harmonisation (ICH) guidelines and exhibited very good specificity, precision, accuracy, linearity, and robustness. The validation results demonstrated a good linear correlation (r = 0.999) between the peak area and the apomorphine concentration, excellent precision (repeatability of 0.23% and intermediate precision of 0.56%), and accuracy (recoveries of 99.72–100.08%). Robustness was confirmed by minimal variation in percentage recovery (R = 1.3%), and specificity was confirmed by the absence of interfering peaks caused by excipients or formulation components. The method has been successfully employed in the analysis of apomorphine and impurities in commercial products, proving itself reliable from batch to batch. This HPLC method represents a significant improvement over conventional methods, as it provides a precise and quicker approach for the quality control of apomorphine medicinal products.