In Phase I, pharmacokinetic studies may be conducted in which subjects?

• A. Only healthy volunteers
• B. Healthy volunteers or patients with the target disease
• C. Only patients with end-stage disease
• D. Only animals

Answer: (B)

Phase I pharmacokinetic studies measure how the body handles a drug and are often done in healthy volunteers to minimize risk and obtain clean PK data. But there are situations where testing in patients with the target disease is necessary or more informative—for example, when the disease state could alter PK or when the drug’s safety profile makes healthy volunteers inappropriate. This is why Phase I PK studies may be conducted in healthy volunteers or in patients with the target disease. Animals are part of preclinical work, not human Phase I studies, and restricting to end-stage disease isn’t required or always appropriate.