Clinical studies are any studies that involve human subjects with any type of disease. Clinical trials are a type of clinical study which is designed to see whether a particular activity, such as drug treatment, is of benefit to people with a disorder, like multiple sclerosis or Parkinson's Disease. Clinical trials are a very important part of medical research. They are essential because they allow us to move from an important discovery which has been made by means of basic research to actual treatments for people with a disorder like MS.
Phase 0 - This is the laboratory phase of drug development.
This phase involves testing possible drug ingredients or drugs using animals with a form of MS. The aim is twofold: To find out if they work and are safe to use. The law of this country and all the other countries doing this kind of research states that all drugs must be tested on animals to make sure that
Animal experimentation is an indispensable part of any drug development programme. It's not just a "nice to have." No drug can be used on humans unless it has first been tested on animals and found to be safe.
Phase 1 The main aim of these studies is to investigate how safe these drugs are for humans to take.
These studies also provide important information on how to give the drug in the most effective ways possible. So these would often include:
Under normal circumstances Phase 1 would use healthy volunteers.
Phase 2 studies are done in people with the disorder which the drug has been developed to treat. They are designed primarily to assess how safe the drug is for people with the disorder and to find out whether or not the drug will be effective.
There are two types of these studies. The second type - Phase 2b studies, are larger than phase 2a studies. They are designed to assess whether the drug is likely to be effective in treating the disorder.
Phase 3 studies are definitive studies in larger number of subjects and are designed to assess whether or not a drug is effective and safe.
If phase 3 studies demonstrate that the drug is both effective and safe, the compound usually becomes licensed by the authorities for use in that particular disease.
When a pharmaceutical company receives a license from the government for a particular illness or disorder, they can then advertise and promote the product to the medical profession.
Phase 4 studies are done after the drug has been licensed.
This includes the process called post-marketing surveillance. This is used to find out whether a particular drug may be associated with rare adverse events or side effects that were not detected in the earlier phases of development. Phase 4 studies also include clinical trial done using the product once it has been licensed for general use. For example, the studies in which two licensed products are directly compared with each other would be classified as phase 4 studies.
Placebo-controlled trials
Placebo-controlled trials are studies where an active drug is compared with
a dummy or inactive compound, called a placebo. The placebo usually looks
identical to the active compound. The aim of these studies is to find out
whether patients get better simply because they feel they are taking a drug
or whether the drug actually works better than the dummy compound
Blinded studies
Blinded studies are studies where both the volunteer participating in the
study and the researcher are unaware or blinded as to whether the volunteer
is getting the 'real drug' or the placebo. Single blinded studies usually
refer to trials in which the researcher knows what the drug is for, but the
person participating in the study does not. . This is sometimes used when
comparing two different injection techniques for example.
Randomisation
Randomisation is the process in which volunteers who enter clinical trials
are randomly assigned to receive the 'real drug' or placebo. Randomisation
is a bit like tossing a coin, although it is usually done by a computer program.
The purpose of the randomisation is make sure that there are no other differences
between the groups apart from the treatment they are given. The randomisation
process maximises the chances that any differences that emerge between the
different treatment groups are due to the different treatments rather than
some other factor. Despite these precautions it is not unusual for the groups
to differ in some respect. This can bias or exaggerate treatment effects or
reduce apparent treatment effects.
Double-blind placebo controlled studies
These are considered the best studies. In these studies both the volunteers
and the people assessing the disease are "blinded" so neither side
know whether the volunteers are taking the 'real drug' or the placebo. In
addition the patients are randomly selected to receive either treatment or
placebo. This means that the researchers can be sure that any differences
between the outcomes in the volunteers who have had the drug and those who
have had the placebo are due to the effects of the drug. They can't give any
information away because they themselves don't know.
Study power
The power of the study refers to the chances that the study can actually find
significant or reliable results.
So the "power" of a study will depend on three things:
In general the power of MS studies increases in proportion to the number of subjects and the duration of the study.
For example, MRI scans are a more powerful measure of MS disease activity than the rate at which a patient might relapse. So if researchers use MRI scans, they need to assess fewer people with MS to get the same level of accuracy as they could when they were studying the relapse rate of patients and comparing those patients who had been given a drug with those who had been given a placebo.
Outcome measures
This is the term which is used to assess whether or not a treatment is effective
or not. In MS the outcome measures in phase 3 studies, (the studies which
lead to the licensing of the specific treatment), are primarily clinical -
or in other words they relate to how well patients 'are' rather than measurements
through tests.
The outcome measures used in DMD studies have been described in the previous "Do DMDs Work?" page.
