What Are All The Various Phases In A Clinical Trial?


Have an idea for a natural-based remedy? Chances are it will still need to be verified with clinical trials, supervised by the FDA.

Trial and Error

Clinical trials are an essential part of modern medicine. Trials like the ones run by Clinical Ink are how our medical professionals find out what works, why it works, what doesn’t work, and where they can improve. Without clinical trials, we would not have access to most of the medication and treatments that we take for granted today. Without doctors and researchers taking the time to properly conduct trials, taking note of any adverse effects, positive effects and after effects, medicine simply would not be what it is. 

Before we go into detail about the different phases of clinical trials, let’s take a look at some information about what clinical trials are from a medical point of view.

What Are Clinical Trials?

Clinical trials are a way for medical professionals to test new medications, new methods of diagnosing illnesses, and ways of slowing or preventing illnesses. The goal of any clinical trial is to determine whether these methods of treating or diagnosing medical conditions are safe and effective enough to offer to the general public. During the course of any clinical trial, many things are evaluated:

  • Different combinations of medications
  • One medication alone
  • Medical devices
  • New ways of using medications previously used for something else.

Intensive research is done before the trial can even begin, often using human cells or animals. Thankfully animal testing is becoming less prevalent. Funding may be secured for a full clinical trial if the initial results are promising. There are many phases within a clinical trial, each one building on the previous one. Let’s take a look at those phases now.

Phase O

This is the first and most minor phase of the trial, usually including no more than fifteen subjects. Medications or devices are tested in very low quantities or for very short periods. If there are no adverse effects for humans and the results are more or less what the researchers expected, the trial will scale up in the next phase.

Phase 1

During this phase, researchers take whatever time they need or are allotted to scale up their human trials. Now the testing to see how much of the medication or device a human being can handle, without adverse side effects, begins. At this stage, around twenty to eighty people are usually brought in as test subjects. Test subjects are monitored closely for reactions because the human body is unpredictable. In addition to the safety and side effects, researchers also test and take note of the safest and most effective ways to use devices or administer treatments. About 70% of trials make it past this phase.

man dosing with CBD cannabis oil

Natural oils are mostly unverified by clinical trials even though your apothecary swears by them.

Phase 2

The trial scales up again in this phase to as many as several hundred subjects. These subjects are people living with the disease that the client aims to help ease or cure, and they are usually given the same safe amount of the medication as the participants in the previous phase. This phase may last for months or even years as researchers monitor their subjects to see how long-term exposure to treatment will affect them. While this clinical trial phase is the largest yet, it is still not large enough to provide sufficient information about the treatment in question. The data collected in phase 2 assists researchers in phase 3. About 33% of trials make it to the next phase.

Phase 3

Once again, the trial will scale up. In Phase 3, trials usually use about 3,000 test subjects in varying stages of the condition in question. This stage of trials can go on for several years. The purpose of such a lengthy phase is to establish how the new medication or device performs compared to existing medications or devices used to treat the illness or condition. For the trial to move forward, there needs to be clear evidence that the new treatment is at least as safe as, but hopefully in some way superior to, existing ones. In this phase, the trial moves into something called “randomization.” Participants are either given the new medication or an existing one to test them against each other; this is usually done in a double-blind format, meaning that neither the researchers nor the participants are aware of who is getting which drug. This method eliminates any bias when interpreting the results. Phase 3 is usually the minimum trial phase for a medication to reach before the FDA will begin their approval process as it is the phase in which most long-term side effects will make themselves known. Between 25 and 30% of trials make it to the next phase.

Phase 4

Phase 4 of any trial only happens after FDA approval. Long-term effects and side effects are monitored as well as any other unexpected benefits. This phase also involves thousands of participants and can go on for many years.

Wrap Up

The numerous phases of clinical trials are all essential, and if any of them are skipped or undertaken without enough care, the results could be disastrous. If you’re applying to be part of a clinical trial, be sure to have all the facts about each phase before you sign up.


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