Polymorphism refers to the existence of multiple crystalline forms of a drug. What is the consequence?

• A. Existence of different isotopes
• B. Existence of multiple crystalline forms with distinct solubilities and stabilities
• C. Existence of multiple hydrated forms
• D. Existence of different crystal habits only

Answer: (B)

Polymorphism means a single drug molecule can crystallize in more than one packing arrangement. Each crystal form has a different lattice energy and molecular arrangement, which changes how tightly molecules are held in the solid. That leads to different physical properties, most notably solubility and stability. A form that is more stable tends to be less soluble and more resistant to degradation or transformation, while a less stable (metastable) form can dissolve more quickly but may gradually convert to the stable form, affecting dissolution, bioavailability, and shelf-life. This is why controlling which polymorph is present is crucial in drug development and manufacturing. Hydrated forms and crystal habit are related concepts but do not alone define the main consequence, and isotopes are not relevant to polymorphism.