Animal models used widely in biomedical research to predict toxicity, safety, and efficacy of interventions in humans (including drugs, nutritional components, and bioactive compounds) are complicated by differences in xenobiotic or drug metabolism between animals and humans.
These differences arise from physiological, anatomical, metabolic, life span, and genetic diversity between species. Among the more straightforward is the simple fact that larger animals, such as humans, generally require smaller drug doses than a strict weight basis would predict due to differences in body surface area.
A simple empirical approach called allometric scaling allows a dose to be scaled and normalized based on differences in body surface area to extrapolate doses from animal science to human research, resulting in a correction factor that is unique to the species.
In the open access paper "A simple practice guide for dose conversion between animals and human," authors Anroop B. Nair and Shery Jacob highlight several key points that should be understood about this approach of allometric scaling for calculating human doses from animal research:
The U.S. Food and Drug Administration (FDA) has established guidelines for determining doses for humans – referred to as the human equivalent dose – in clinical trials. The process involves determining the no observed adverse effect level (NOAEL) in a particular animal species and then converting the NOAEL to the human equivalent dose based on body surface area.
For more information about determining human equivalent doses, please see these resources: