Before a pharmaceutical company can initiate testing in humans, it must first conduct extensive research. This research typically involves years of experiments on animal and human cells. The compounds are also extensively tested on animals. If this stage of testing is successful, an organisation will then request approval to begin testing the drug in people.
A clinical trial usually involves doctors and nurses as well as social workers and other health care professionals. They will check the health of the participant at the beginning of the trial, give them specific instructions for participating in the trial, monitor the participants carefully during the trial, and stay in contact with them once the trial is completed.
A person taking part in the trial of a new drug could be involved in one or more phases of the research. The testing is normally done in three phases, with each successive phase involving a larger number of people.
A Phase I Study
Phase I studies are primarily concerned with assessing the drug's safety. This initial phase of testing in humans is done on a small number of healthy volunteers (between 20 and 80), who are usually paid for participating in the study. The study is designed to determine what happens to the drug in the human body, mainly how it is absorbed, metabolized, and excreted. A phase I study will also investigate side effects that might occur as dosage levels are increased. This initial phase of testing typically takes several months. About 70% of experimental drugs pass this initial phase of testing.
A Phase II Study
Once a drug has been shown to be safe, it must be tested to see if it works. This second phase of testing may last from several months to two years, and involve up to several hundred patients. Only about 30-35% of experimental drugs successfully complete both phase I and phase II studies. Most phase II studies are conducted as randomized and blinded trials
A Phase III Study
In a phase III study, a drug is tested on several hundred to several thousand patients. This large-scale testing provides the pharmaceutical company with a more thorough understanding of the drug's effectiveness and the possible side effects it may have. Most phase III studies are also conducted as randomized and blinded trials.
Phase III studies typically last several years. 70-90% of drugs that enter phase III studies successfully complete this phase of testing. Once a phase III study is successfully completed, a pharmaceutical company can apply for approval to market the drug.
In addition, pharmaceutical companies also carry out post-marketing or late phase III/phase IV studies.
What is a randomised control trial?
Most phase II and all phase III trials are randomised trials. One group of patients will receive the experimental drug, while a second control group will receive a standard treatment or placebo. A placebo is a treatment that looks the same as the experimental drug but has no effect on the body. It is a dummy pill. Often these studies are blinded or ‘double-blinded.’
What is a control group?
A control group is a group of clinical trial participants who receive the placebo or standard therapy for a condition while another group is given the experimental treatment. The control group serves as a measuring stick to gauge the effectiveness of the experimental treatment.
What is an experimental group?
An experimental group is a group of participants in a clinical study who receive the actual drug or treatment being studied.
What is a blind trial?
A blind trial is a trial in which the subject does not know if he or she is part of the experimental group or the control group
What is a double-blind trial?
A double-blind trial is clinical trial in which neither the participants receiving the treatments nor the researchers administering the treatments are aware of which group is receiving the experimental treatment. The purpose is to eliminate any bias in reporting of results.