Analytical strategies for complex injectables: the expanding role of LC-MS technologies.

Complex injectable therapeutics, including lipid nanoparticles, antibody-drug conjugates, biotherapeutics, and long-acting delivery systems, present analytical challenges that frequently exceed the capabilities of conventional pharmaceutical testing approaches. Liquid chromatography-mass spectrometry (LC-MS) has emerged as a key analytical platform for addressing these challenges through sensitive quantification, structural characterization, and quality assessment of complex drug products. This review critically examines the evolving role of LC-MS in the development, characterization, quality evaluation, and regulatory assessment of complex injectable formulations, with emphasis on the analytical considerations that influence method selection and performance. Particular attention is given to the capabilities and limitations of contemporary LC-MS approaches for increasingly heterogeneous and structurally complex formulations. Despite significant advances, challenges associated with matrix complexity, data interpretation, and analytical harmonization continue to limit broader implementation. Future progress will depend on standardized analytical workflows, improved reference materials, and greater integration of advanced mass spectrometry technologies into pharmaceutical development and quality systems. Overall, LC-MS has evolved into an indispensable platform for ensuring the quality, safety, and performance of next-generation complex injectable therapeutics.