Which phase of a clinical trial focuses primarily on safety and dose in healthy subjects?

The phase of a clinical trial that focuses primarily on safety and the appropriate dosage in healthy subjects is Phase I. During this initial stage, the primary objective is to assess the safety profile of a new drug or treatment, including identifying any potential side effects. Healthy volunteers are often selected to minimize variability in the response to the treatment, allowing researchers to gather critical data on how the drug behaves in the human body.

Additionally, this phase helps in determining the pharmacokinetics and pharmacodynamics of the treatment, which are essential for understanding how the drug is absorbed, distributed, metabolized, and excreted. By evaluating various dose levels, researchers can also identify the maximum tolerated dose, which informs dosage levels for subsequent phases of the trial. The insights gained in Phase I are crucial for ensuring that the treatment is safe enough to move forward into the larger and more focused trials conducted in Phase II and Phase III, where efficacy becomes the primary focus along with continued safety assessment.

Overall, Phase I lays the groundwork for later phases by ensuring that safety concerns are addressed before testing the drug's effectiveness in patients with the targeted condition.