What Are The 4 Clinical Trial Phases?

In many countries, including the USA, pharmaceuticals (drugs) and many types of medical devices have to get approval from a regulatory agency before they can be marketed to customers. In the U.S., the Federal Drug Administration (FDA) is the regulatory body of note. To receive FDA approval pharmaceutical companies and device innovators have to go through a stringent approval process before getting the FDA’s stamp of approval.

A big part of receiving approval revolves around getting past some very strict clinical testing guidelines. This offers the FDA assurance that the drug and device under consideration are safe with a minimum of potential side effects. To be clear, the testing guidelines are set forth by the FDA. It’s the drug and device developers and manufacturers that have to worry about compliance issues.

Because of the vast importance of the clinical testing process, it would seem prudent at this time to discuss what the 4 clinical trial phases are. 

Before discussing the actual clinical trial phases, it’s important to understand what the FDA expects to see in the form of results from the trial process. There are in fact three important questions to which the FDA wants answers. The three questions are:

  • Does the Drug or Device work on real people?
  • Is the Drug or Device safe?
  • Does the Drug or Device serve as a better treatment alternative to other types of treatments?

If a particular clinical trial points to positive answers to all three questions, there is a very good chance the associated drug or device will eventually get the FDA’s approval.

It’s also important to note there are two other important steps that researchers must take before getting approval to even run a clinical trial. First, they must provide evidence the drug might work and be safe for humans. They can do this through preclinical (or laboratory) studies on cells and animals.

Second, they must submit an investigational new drug (IND) application. The application must provide the laboratory evidence from testing on cells and animals, drug ingredients, an outline for the planned clinical study, and the credentials of members of the trial team. If everything is in order, the FDA will give the green light for the trial to go forward.

Without further delay, here are the four clinical trial phases.

Phase 0 (Zero) – Exploration Phase

The real purpose behind phase 0 is to give researchers a way to find out and prove that a drug does in fact do what it is intended to do for humans. In this phase, testing is done on very few volunteers with very small doses. Expectations in this phase do not include providing emphatic proof a drug or device will work. The goal is to only show that the drug or device will address the specific issue the drug or device was developed to address.

Phase I – Safety Testing

This is the first phase where people participate at meaningful levels. The ultimate goal of this phase is to determine the highest dose of the applicable drug that can be given to a subject and the drug still be deemed safe.

With safety as the main concern, researchers will be looking closely at how subjects react to the drug and what it does to their bodies. In this phase, the number of subjects is generally limited to less than 20. Also, there is no blind testing done at this level.

Phase II – Confirmation the Treatment Works

If the drug or device is deemed safe, phase II ensues. At this level, the number of subjects generally rises to somewhere between 25 and 100. Researchers will be looking for undeniable evidence that the drug or device is an effective treatment alternative to the medical issue that’s under scrutiny. All subjects get the same doses or treatments and the results are recorded accordingly. Again, there is no blind testing at this level.

Phase III – Better Treatment?

If a drug or device is safe and works, that means little to the FDA if there are still better treatment alternatives already on the market. To prove that a new treatment is better, volunteer testing is done on a large scale across a wide range of people. Some blind testing is done for a better understanding of cause and effect. These studies can last months, often long enough to get clear evidence the drug or device is a better treatment alternative.

Getting FDA Approval

When all the clinical evidence is in, the FDA will hold a hearing. This gives attorneys from both sides a chance to step in and offer testimony as to the viability of the drug or device. If someone chooses to call in a clinical trial expert, this would be the time. Based on testing results and testimony, the FDA will eventually make its final decision.

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