List of Animal Models Used in Nonclinical Studies

Nonclinical animal studies using defined animal models are a critical step in new drug development. Different species show differing propensities to develop specific diseases, and feasibility factors—such as ease of handling and husbandry—also influence species selection. In addition, animal studies must be conducted under applicable regulations.

This overview outlines the importance of animal studies, the criteria for species selection, and the regulations and ethics that govern experimental environments and the use of live animals.

Importance of Animal Studies and Species Selection

In studies that support new drug development, appropriate use of nonclinical models and species is fundamental to generating data that can predict responses in humans. This is especially important for biologics. Consequently, science-driven strategies are used to select the most predictive test systems and species.

Species Selection Criteria

Species are selected based on similarities to humans in pharmacodynamics (PD), pharmacokinetics (PK), physiology, and pathophysiology. Rodent and non-rodent species are commonly used as disease models in which data from nonclinical studies support initial dose calculations and projections of therapeutic dose ranges for subsequent clinical development.

Feasibility is also an important consideration. Availability of animals and ease of handling in a standard laboratory environment are evaluated so that studies are conducted efficiently and ethically.

Regulations and Ethics of Animal Research

Animal research is an important means of advancing human health and welfare; at the same time, animal welfare must be respected. In Japan, strict standards for the care and use of laboratory animals have been established under the Act on Welfare and Management of Animals.

The 3Rs (Replacement, Reduction, Refinement)

When conducting animal studies, adherence to the 3Rs is required:

• Replacement: Whenever possible, use non-animal methods (e.g., cell-based studies).
• Reduction: When animals are used, minimize the number used to achieve scientific objectives.
• Refinement: Use the most refined techniques available to minimize pain and distress.

Researchers must carefully consider the necessity and ethical appropriateness of any animal study. Protocols are generally reviewed by an ethics committee, and study designs and procedures undergo rigorous review. This process helps ensure that scientifically useful data are obtained while maximizing consideration for animal welfare.