Analytical techniques for methyldopa and metabolites: a comprehensive review

Methyldopa, a centrally acting α2-adrenergic agonist, remains a key antihypertensive drug, particularly prescribed for pregnant and renal-impaired patients. Its clinical significance has led to extensive research aimed at developing reliable analytical methods for its accurate, sensitive, and selective determination in pharmaceutical formulations and biological matrices. Relevant literature was retrieved from Scopus, Web of Science, ScienceDirect, PubMed, and Google Scholar, restricted to English-language publications. This review critically examines the diverse analytical approaches used for Methyldopa quantification, outlining their principles, advantages, limitations, and applicability in both advanced and resource-limited settings. Chromatographic methods, especially high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS/MS), remain the most robust techniques, offering excellent sensitivity (LOD: 10-50 ng/mL for HPLC; as low as 0.7-15 ng/mL for LC-MS/MS) with rapid analysis times. While LC-MS/MS provides superior detection, it is limited by high costs and technical expertise requirements. Electrochemical methods, particularly voltammetry, stand out for their affordability, rapid analysis, and feasibility in decentralized laboratories, achieving LOD values as low as 0.01-0.05 µM. Spectrophotometric approaches, primarily UV-Vis, remain the simplest and most cost-effective options, making them useful for routine quality control, though with reduced selectivity and higher detection limits. Key analytical challenges include Methyldopa's low concentration in biological fluids, chemical instability, and matrix interferences. This review provides a comparative evaluation of chromatographic, spectrophotometric, and electrochemical techniques, emphasizing the need for portable, low-cost platforms to expand accessibility in therapeutic monitoring. Overall, it offers critical insights for advancing Methyldopa analysis and improving clinical management in diverse healthcare settings.