What is the primary source of data for a Phase I new drug study in humans?

In a Phase I new drug study, the primary source of data is preclinical data. This stage of clinical research is critical as it involves the first administration of a new drug to humans to assess safety, tolerability, pharmacokinetics, and pharmacodynamics. Prior to any human trials, extensive preclinical studies are conducted, often using animal models and cell cultures, to gather essential data on the drug's potential effectiveness, safety profile, and appropriate dosing.

The information gathered during preclinical research informs not only the design of the Phase I trial but also helps regulatory authorities assess the drug's potential risk versus its potential benefit when deciding whether to approve the initiation of the clinical trials in humans. This foundation is crucial because it lays the groundwork for understanding how the drug behaves in living organisms, which is exceptionally important when first testing it in humans, who may respond very differently than animal models.

In contrast, the other options represent different components of drug development or maintenance phases. Clinical trials encompass all trial phases after the preclinical stage, FDA files contain regulatory documentation from the agency concerning approved drugs, and postapproval surveillance studies occur only after the drug has already been approved and is on the market. Thus, preclinical data is indeed the primary source of data