Saturday, August 19, 2006

Clinical Trials: Phase 1, 2 , 3 and 4 ---(4)


Phase 4 trials are done after a drug has been shown to work and has been granted a license. So they are looking at drugs that are already available for doctors to prescribe, rather than new drugs that are still being developed.

The main reasons pharmaceutical companies run phase 4 trials are to find out

* More about the side effects and safety of the drug
* What the long term risks and benefits are
* How well the drug works when it’s used more widely than in clinical trials

There is more information about the different phases of clinical trials on the website of The Association of the British Pharmaceutical Industry (ABPI).

Source: Cancer Research UK

Clinical Trials: Phase 1, 2 , 3 and 4 ---(3)


These trials compare new treatments with the best currently available treatment (the standard treatment). They may compare

* A completely new treatment with the standard treatment
* Different doses or ways of giving a standard treatment
* A new schedule of treatment with the standard one

Phase 3 trials are usually much larger than phase 1 or 2. This is because differences in success rates may be small. So, you would need many patients in the trial to show the difference.

For example, 6% more people get a remission with a new treatment compared to standard treatment. If a phase 3 trial gave the new treatment to 50 people and the standard treatment to 50, on average, there may be 3 more remissions in the new treatment group. The 2 groups would not look that different. If they gave each treatment to 5,000 people, there could be 300 more remissions in the new treatment group.

Sometimes phase 3 trials involve thousands of patients in many different hospitals and even different countries.


Phase 3 trials are usually randomised. This means the researchers put the people taking part into 2 groups at random. One group gets the new treatment and the other the standard treatment. There is more about randomisation and different types of trials in this section.


Trial overviews are studies that combine all the results from phase 3 trials of a new treatment. They are sometimes called meta-analyses. The idea is to get a broader picture of how well a treatment works. The more data (information) you have, the more accurate the results are likely to be.

Source: Cancer Research UK

Clinical Trials: Phase 1, 2 , 3 and 4 ---(2)


About 7 out of every 10 (70%) new treatments tested at phase 1 make it to phase 2 trials. These trials may be done on people who all have same sub-type of the disease, or with several different sub-types of the disease. Phase 2 trials are done to find out

* If the new treatment works well enough to test in phase 3
* Which sub-types of the disease it is effective against
* More about side effects and how to manage them
* More about the most effective dose to use

Although these treatments have been tested at phase 1, you may still have side effects that are not known about. Drugs can affect people in different ways.

Phase 2 trials are often larger than phase 1. There may be up to 50 people taking part. If the results of phase 2 trials show that a new treatment may be as good as existing treatment, or better, it then moves to phase 3.

Source: Cancer Research UK

Clinical Trials: Phase 1, 2 , 3 and 4 ---(1)


These are the earliest trials in the life of a new drug or treatment. They are usually small trials, recruiting anything up to 30 patients (often a lot less).

When laboratory testing shows a new treatment might help treat a certain disease, phase 1 trials are done to find out:

* The safe dose range
* The side effects
* How the body copes with the drug
* If the treatment shrinks cancer

The first patient to take part will be given a very small dose of the drug. If all goes well, the next person will get a slightly higher dose. With each patient taking part, the dose will gradually be increased and the effect that has will be monitored. Any side effects will be recorded.

In a phase 1 trial, you may have lots of blood tests, as the researchers look at how the drug is affecting you. And at how your body copes with, and gets rid of the drug.

People entering phase 1 trials often have severe disease and have usually had all the treatment available to them. This is because they may benefit from the new treatment in the trial, but many won't. The aim of the trial is to look at doses and side effects. This work has to be done first, before we can test the potential new treatment to see if it works. Phase 1 trials are important because they are the first step in finding new treatments for the future.

Source: Cancer Research UK

This page is powered by Blogger. Isn't yours?