Final answer:
A drug that differs in strength, quality, or purity from established standards is described as adulterated or misbranded, and is regulated by the FDA to ensure safety and efficacy.
Step-by-step explanation:
If a product's drug strength, quality, or purity of the drug differs from compendia standards, it is described as adulterated or misbranded. The U.S. Food and Drug Administration (FDA) regulates drugs to ensure safety and efficacy. New drugs must go through a rigorous approval process known as a New Drug Application (NDA) before they can be prescribed. Generic drugs are required to have the same therapeutic effect and safety profile as their brand-name counterparts, and any deviation from this can lead to similar legal classifications of adulteration or misbranding.