Which phase of clinical trials primarily focuses on safety and tolerability?

The focus of Phase I clinical trials is primarily on assessing the safety and tolerability of a new drug or treatment. During this phase, a small group of participants is administered the experimental treatment to evaluate how it affects their bodies. The main objectives include determining the appropriate dosage, understanding the pharmacokinetics (how the drug is absorbed, distributed, metabolized, and excreted), and identifying any potential side effects or adverse reactions.

Participants in Phase I trials are typically healthy volunteers, which allows researchers to better isolate the effects of the drug without the confounding factors often present in patients with conditions affecting their health. The goal is to establish whether the treatment is safe enough to proceed to the next stages of clinical testing, where the focus will shift to its efficacy in participants who have the condition being treated.

In contrast, the other phases focus on different aspects of drug development. Phase II trials evaluate the effectiveness and further assess safety in a larger group of patients who have the disease or condition. Phase III trials are designed to confirm effectiveness, monitor side effects, and compare the treatment to standard or equivalent treatments on a larger scale. Phase IV trials occur after the drug has been approved for public use and may look into long-term effects, benefits, and risks