preclinical

Preclinical refers to the stage of biomedical development that precedes testing in humans. It encompasses laboratory experiments and animal studies designed to understand a candidate therapy, device, or diagnostic, including its mechanism of action, potential efficacy, pharmacokinetics, toxicology, and dosing strategies. Findings from preclinical work inform whether early human testing is warranted and how to design initial clinical studies.

In vitro methods use cell cultures and biochemical assays to characterize biological activity and potency, while in vivo studies in animals assess pharmacokinetics, pharmacodynamics, safety, and potential adverse effects at estimated human exposures. Researchers often choose multiple models to capture species differences and to identify dose ranges and routes of administration.

Regulatory agencies require robust preclinical data to support an application for clinical trials. In the United States, data support an Investigational New Drug filing; in Europe, a Clinical Trial Authorization is needed for medicines. For medical devices, similar preclinical evidence supports an Investigational Device Exemption or equivalent submissions. Preclinical results are not fully predictive of human outcomes but help assess risk.

The scope of preclinical work extends across pharmaceuticals, biologics, gene therapies, vaccines, and medical devices. It may incorporate additional tools such as computational modeling, in vitro organ systems, and, when appropriate, alternative methods to reduce animal use under the 3Rs framework (replacement, reduction, refinement).

Successful preclinical results enable progression to human trials. Negative or inconclusive findings can lead to redesign, further studies, or termination of development to avoid exposing patients to undue risks.