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Phase III Trials

Few drugs ever make it past Phase II clinical trials. However, for the one-third of investigational drugs that do, these drugs move on to Phase III research. Phase III clinical trials are conducted to ultimately assess the efficacy of an investigational drug to treat or cure a targeted condition. These clinical research studies require the largest patient populations and longest amount of time to conduct its research.

Phase III Research: Who Participates?

Phase III research can involve anywhere from 300 to 3,000 participants, making this type of clinical trial the largest. In addition, the participants must be afflicted with the targeted condition for which the investigational drug is intended. Thousands of participants with similar demographic traits are tested over the span of two to five years in Phase III research. Therefore, Phase III clinical trials are the longest and most complicated studies in which to be involved.

Phase III Research: Why is in Conducted?

For the few drugs that make it to Phase III clinical trials, the drugs’ efficacy and safety are further tested against an existing treatment or placebo. Dosage is also evaluated as to find the dose that provides the most beneficial side effects with the least negative effects. In addition, Phase III research can assess the effectiveness of the drug for varying levels or degrees of the disease. Though only one-third of drugs that make it to Phase III research, almost 80% progress to Phase IV trials.

Common Questions:

What is a Clinical Research Trial?
Why Participate in a Clinical Research Trial?
Is there a difference between Clinical Trials and Treatment?
How are New Drugs Tested?

Learn More About Clinical Trials:

Phase I Clinical Trials
Glossary of Clinical Trial Terminology
Alabama Health Resources
Brief History of Clinical Trials
Find Clinical Trials

Know Your Rights as a Participant:

Your Patient Rights
Patient Privacy Rules
Informed Consent Agreement
NIH Patient Bill of Rights
Legal, Ethical, and Safety Issues