Phase I Clinical Trials → Trial Design

Phase I trials typically involve 20 to 100 healthy volunteers or patients with the disease/condition of interest. A caveat here is that if the medication or intervention is designed for use in cancer, cancer patients should always be the participants in a Phase I study. This phase typically lasts several months with the purpose of determining the drug’s safety profile and appropriate dosage. Phase I studies also assess metabolic and pharmacologic activity in humans.

Initially the first people who participate in the study get a low dose of the treatment under strict supervision and guidance. If there are only minor side effects, the next few get a higher dose. This process will continue until the researchers find a dose that strikes a balance between expected effectiveness and acceptable side effect profiles.

Side effects are continually monitored throughout clinical trial phases, but Phase I may only see acute, short-term side effects. More long-term side effects are typically observed in Phase II and III studies.

For those with life-threatening conditions (e.g., cancer), the potential benefits compared to the risks when many options have been tried may possibly contribute to disease response, even though it is not a goal of the current phase. It is therefore important to note that placebos (inactive treatments) are not used in Phase I trials.