Understanding Clinical Trial Phases

You may have seen on the news or read about the new asthma medications that are coming to market  While they may not be on the market quite yet. They are in development and “close”. Close is relative depending on the phase and outcomes. There is a lot of hurry up and wait when you are a patient hoping for new medications to come to market that will hopefully improve your quality of life.

Have you ever wanted to know what phases are involved in clinical trials and how new medications are put through the pages?  Here is a rundown of the clinical trial phases from the FDA (U.S Food and Drug Administration). 1

Phase 1

Patients: Healthy volunteers and those with the disease condition

Approximately 20-100 people participate

Length of study: several months

Purpose: safety and dosage. Essentially, these studies will monitor and obtain information on hoe the drug reacts in humans. Researchers will make adjustment on dosing from animal, models, monitor side effects  and assess effectiveness.

Interesting fact: Approx. 70% of drugs move to the next phase

Phase 2

Patients: These studies enrol several hundred patients with the disease/condition

Length of study: several months to 2 years

In Phase 2 studies, typically involve a few hundred patients, and these studies aren't large enough to show whether the drug will be beneficial. Research in this stage looks to provide researchers with additional after data, to refine research questions, develop research methods and  design Phase 3 trials.

Interesting fact: 33% of drugs move on to the next phase.

Phase 3

Patients: 300 to 3,000 volunteers who have the disease or condition

Length of Study: 1 to 4 years

Purpose: Efficacy and monitoring of adverse reactions. This is the phase in which researchers will determine if there is treatment benefit. These studies provide the largest amount of safety data. These studies typically show long term or rare side effects that may have done undetected.

Phase 4

Patients: Several thousand volunteers who have the disease/condition

Purpose: Safety and efficacy

Phase 4 trials are carried out once the drug or device has been approved by FDA during the Post-Market Safety Monitoring

More interesting facts: As long as trials are thoughtfully designed, safeguards participants and meets Federal standards, the FDA allows a wide scope in clinical trial design.

While the phases of clinical trials provide the data, drug developers still need to apply for approval to conduct research to protect volunteers. There are stringent requirements and review committees. All of this needs to happen before any research can begin.  It is amazing how many safeguards they have in place. The best part is that, there are a lot of opportunities to ask questions about these processes and what will be involved in a particular study. In my experience, most clinician/researchers that are involved in carrying out research are very transparent about the process they take and what regulations they follow to be able to participate in studies.

If you have an interest in participating in a study there are number places to look for information. You can check your local asthma clinic, university research programs or hospitals that are associated with research programs often have lots of advertisements posted in clinics or hospital built-in boards in the elevators. There are also sites to check out for example www.clinicaltrials.gov which is the most comprehensive


By providing your email address, you are agreeing to our privacy policy.

More on this topic

This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The Asthma.net team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.

Join the conversation

or create an account to comment.

Community Poll

Does humidity impact your asthma?