Courtesy of Tris Pharma Medical Affairs.

This site is intended for U.S. healthcare professionals only.

Study designs Study Designs

Overview and terminology73,74

Clinical studies of treatments in humans are classified into phases 73,74

Phase I

Small number of healthy volunteers who are closely monitored in a clinical setting

Determines a safe dosage range and identifies any common side effects or readily apparent safety concerns

May also be used to develop pharmacokinetics (PK) and pharmacodynamics (PD), to assess the half-life of the drug, estimate the maximum tolerated dose (MTD), or evaluate the effects of multiple dose levels

Phase II

May be >100 subjects

Investigates preliminary evidence of efficacy and continues to monitor safety

May be the first time the agent is administered to patients with the disease of interest to answer questions such as: What is the correct dosage for efficacy and safety in the patient type? What is the probability a patient treated with the compound will benefit from the therapy or experience an adverse effect?

Phase III

May be >1,000 subjects

Rigorous clinical trial with randomization, one or more control groups, and definitive clinical endpoints

Address questions of comparative treatment efficacy

 Involves a placebo and/ or active control group in order to assess the precise and valid estimates of differences in clinical outcomes attributable to the investigational therapy agent

Phase IV

Very large; may be >10,000 patients

Postmarketing surveillance (PMS) occurs after regulatory approval of the new agent

Opportunity to learn about rare side effects and interactions with other therapies

Can provide important information that was not apparent during the drug development

Clinical studies of treatments in humans are classified into phases 73,74

Phase I

Small number of healthy volunteers who are closely monitored in a clinical setting

Determines a safe dosage range and identifies any common side effects or readily apparent safety concerns

May also be used to develop pharmacokinetics (PK) and pharmacodynamics (PD), to assess the half-life of the drug, estimate the maximum tolerated dose (MTD), or evaluate the effects of multiple dose levels

Phase II

May be >100 subjects

Investigates preliminary evidence of efficacy and continues to monitor safety

May be the first time the agent is administered to patients with the disease of interest to answer questions such as: What is the correct dosage for efficacy and safety in the patient type? What is the probability a patient treated with the compound will benefit from the therapy or experience an adverse effect?

Phase III

May be >1,000 subjects

Rigorous clinical trial with randomization, one or more control groups, and definitive clinical endpoints

Address questions of comparative treatment efficacy

 Involves a placebo and/ or active control group in order to assess the precise and valid estimates of differences in clinical outcomes attributable to the investigational therapy agent

Phase IV

Very large; may be >10,000 patients

Postmarketing surveillance (PMS) occurs after regulatory approval of the new agent

Opportunity to learn about rare side effects and interactions with other therapies

Can provide important information that was not apparent during the drug development

References

73. United States Food and Drug Administration (FDA). Drug Development Process. Available at https://www.fda.gov/ForPatients/Approvals/Drugs/ucm405622.htm#Clinical_Research_Phase_Studies.
74. Pennsylvania State University. STAT 509: Design and Analysis of Clinical Trials. 3.4: Clinical Trial Phases. Available at https://onlinecourses.science.psu.edu/stat509/node/22/.