Methyldopa hydrate (C₁₀H₁₃NO₄ · H₂O) is a pharmaceutical reference standard and research chemical used as a centrally acting antihypertensive agent. It is a prodrug converted to α-methylnorepinephrine, which stimulates central α₂-adrenergic receptors, reducing sympathetic outflow and blood pressure. Commonly applied in pharmacological studies, hypertension research (including gestational hypertension), and analytical method development. High-purity grades (≥98%) are suitable for laboratory and pharmaceutical R&D use.