Allometric scaling is one of the tools that drug developers use to predict human PK based upon animal data. Prediction methods, like allometric scaling, provide a “sneak peek” at how a drug might behave in humans before any clinical studies are conducted. This is important information for both drug developers and regulators (like the FDA) because it provides a data-driven foundation for establishing a safe starting dose in humans. Allometric scaling comes from two words: ALLOMETRY: The study of size and its consequences SCALING: An engineering term meaning to adjust (or “scale”) dimensions (or other parameters) with size In biology, the basis of allometric scaling lies in the relationship between metabolic rate (defined as the rate of biological life processes and metabolism) and the body size of the animal. The metabolic rate that is used in allometry includes life processes such as number of heart beats or number of breaths in the lifespan of the animal as a function of size. It is critical to understand that as body size increases from one animal species to another, metabolism slows down. To exploit this, allometric scaling uses mathematical models to describe physiological, anatomical, and biochemical changes in animals as their size changes. Of specific interest for drug development, this approach can predict important PK information for humans using experiments conducted in various animal species.