What Are Clinical Trials?
The Importance of Clinical Trials
Clinical trials provide the
medical community with scientific data about the
potential benefits of new treatments, drugs,
surgeries, and devices. In some cases, they may
provide patients with the only options for
improvement of their conditions. This important
work also contributes to advances in the
understanding and treatment of neurological
disorders. By participating in these trials, we
can offer patients opportunities not available at
most health-care facilities.
 How
Clinical Trials are Conducted
From the
beginning of the pre-clinical phase until final
approval by the Food and Drug Administration (FDA),
clinical trials of new drugs can take a number of
years to complete. There are usually five phases of
drug development:
Pre-clinical phase - In
this phase drugs are studied in vitro, (in a cell
culture) or in vivo, using animal models to evaluate
the safety and potential effectiveness in treating
targeted diseases. Scientists are able to obtain a
significant amount of information about how a drug
may act when used in humans. Once this phase is
completed (1 - 3 years), the pharmaceutical company
submits the data to the FDA and requests approval to
begin testing the drug in humans.
Phase I - This is the initial
phase of testing in humans, using a small number of
healthy volunteers to assess drug safety. Scientists
determine what happens to the drug in the human body,
how it is absorbed, metabolized, and excreted. About
70% of experimental drugs pass phase one of testing.
Phase II - Once
a compound has been shown to be safe, it must be
tested for efficacy. This second phase of testing may
last from several months to 2 years, and involves
several hundred patients. Most phase two studies are
randomized trials. One group of patients will receive
the experimental drug while a second control group
will receive either a standard treatment or a
placebo. Approximately one third of experimental
drugs successfully complete both phase one and phase
two studies.
Phase III - In this phase, the drug
is tested in several hundred to several thousand
patients. This large scale testing provides the
pharmaceutical company and the FDA with a more thorough understanding of the
drug's effectiveness,
benefits and range of possible side effects. Most of
these studies are also randomized trials with an open
label extension. Of the drugs that enter phase three
studies, 70% to 90% successfully complete testing.
Once the data from a phase three study is analyzed a
pharmaceutical company can request FDA approval for
marketing the drug.
Late Phase III and Phase IV - These studies
are also referred to as post marketing studies. Pharmaceutical companies
can achieve several objectives in these studies. These include comparing
the drug with other drugs already on the market, monitoring a drugs long-term
effectiveness and impact on a patient’s quality of life, and determining
the cost-effectiveness of a drug therapy to other traditional and new
therapies.
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