Clinical Research Studies: Understanding Trials
Clinical Trial Phases; Phase I, II, III and IV Studies
Oct 31, 2009
Clinical trials vary tremendously; some test new experimental drugs; others test drugs already on the market. Paid clinical trials are not unusual; some clinical trials don’t offer money, but give free drugs or treatment to patients participating. Clinical research studies start with Phase I studies; there are four different levels of clinical trials, and each recruits a different type of clinical trials patient.
Phase I Clinical Trials
A phase I clinical trial tests drug or devices not yet approved for use. A clinic trials patient in a phase I study doesn’t have a disease or problem that the drug or device being tested would help; phase I volunteers are usually healthy. Phase I studies are done to prove not that the drug or device will help, but to make sure it won’t cause any harm to healthy people. Phase I studies, sometimes called safety studies, are usually small, with less than 100 people studied. They’re not usually done in doctors' offices, but in centers that specialize in phase I clinical trials.
Phase II Clinical Trials
Phase II clinical trials are done after the phase I study. Phase II clinical studies are usually small, but larger than phase 1 clinical studies; they may test several hundred patients. Phase II study patients have the target disease but no other health problems that could affect the outcome of the testing.
These studies usually have two groups within them; one group gets the drug, the other group is given a placebo, which contains no medication at all. If the study is a double blind study, neither the patient nor the staff know whether the patient is getting active drug or a placebo.
Phase II trials may be done at centers that specialize in clinical trials, or through doctors' offices. All patients at all trial sites sign the same consent and are studied and monitored in the exact same way, to prevent results from varying due to office practices.
Phase III Clinical Trials
If the phase I clinical trial shows a drug has no serious side effects, and the phase II study shows that the drug has efficacy, or is effective, phase III clinical trials begin. Like phase III trials, patients are divided into at least two random groups, with one group receiving the actual drug and the other a placebo. There may be three groups, with two receiving the drug in different quantities, and one receiving the placebo.
Phase III clinical studies are large, containing a thousand or more patients, usually done in doctor’s offices, and are aimed at showing the following:
- Long term effectiveness
- Long term safety
Phase III clinical trials take several years to complete. If a drug still shows promise after all the data is analyzed, a New Drug Application (NDA) can be filed with the FDA, asking permission to market the drug for sale.
Phase IV Clinical Trials
Phase IV studies are done after the NDA is filed and the drug is marketed. They may be done to compare another drug on the market with the new drug, to test different doses for effectiveness, or to familiarize doctors with the new drug. A Phase IV study may also be designated to test the long term safety of a drug. An article published in USA Today, written by Rita Rubin, entitled, “How did Vioxx debacle happen?” points out the risks of new drug development, even after a drug has undergone numerous trials.
Benefits of Clinical Trial Data
Clinical trials are essential for the development of new drugs. They’re also important for determining the long term safety of drugs; sometimes a drug that tests well with minimum or acceptable side effects in early clinical trials is shown to have serious effects in long term studies.Clinical trials are designed to keep drugs from being rushed to market without adequate testing, but even after phase I-IV trial testing, a drug can later be shown to have unexpected side effects.
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