Topic overview

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Polymorphism is the ability of a solid drug or excipient to exist in multiple crystalline forms with the same chemical composition. Differences in crystal structure can affect properties such as melting point, density, hardness, hygroscopicity, solubility, and dissolution. The relationship between forms and their stability under particular temperature and pressure conditions is described as enantiotropic or monotropic. Changes between forms may alter drug performance, while crystal habit can influence manufacturing operations. The topic also distinguishes polymorphs from amorphous material and covers solvates and hydrates, analytical characterization, and transitions induced by processing or storage. These concepts support early selection and control of suitable solid forms, including attention to batch consistency and regulatory expectations.