Clinical trials test drug candidates for safety and effectiveness.
Clinical Trial Basics
A clinical trial, also called an interventional study, tests new drugs and treatments. It can also test new applications for approved drugs or treatments (for example, using drugs in different combinations or for different diseases). This is different from an observational study, which records data about participants according to a predetermined schedule and process, but offers no drugs or treatments. The process can be long, complicated, and difficult.
How Clinical Trials Work
The following is a summary of the clinical trial process.
Clinical Trial Phases
A drug must pass each individual phase of a clinical trial before advancing. The number of participants in each phase can vary. The numbers given below are typical of trials for an orphan disease such as SMA.
- Phase 1 tests safety and dosage levels, usually on 10-20 individuals. Sometimes, these volunteers are healthy individuals. However, for an orphan disease like SMA, some or all may be patients with the condition being studied.
- Phase 2 tests a slightly larger group, usually 20-40 individuals, all of whom have the condition being studied.
- Phase 3 increases the number of people tested—up to 100-200 including the control or placebo group. A drug that passes these three phases can be approved and marketed to the general public.
- Phase 4 primarily involves ongoing evaluation and monitoring, even after a drug is approved for the general public.
The First Steps
Researchers test new therapies in the laboratory and in animal studies, and those with the most promising results are moved into clinical trials.
Funding for clinical trials can come from physicians, medical institutions, foundations, voluntary groups, pharmaceutical companies, or federal agencies.
Clinical Trial Protocols
A protocol is a study plan for a clinical trial. It covers important details like:
- Who can participate. These rules, called “inclusion and exclusion criteria,” typically include age, stage or type of disease, previous treatment history, and other medical conditions.
- What procedures, medications, and dosages will be given, and how often.
- When the participants must see a study doctor, and what tests or measurements the doctor will use to evaluate them.
- How the control group (if any) will be set up. Participants assigned to a control group will receive a placebo—an inactive pill, liquid, or powder—or a standard treatment. The other group is given the experimental treatment. Participants are often not told which group they are in, and the researchers may not know either. This “double-blind” format keeps participant or researcher bias from affecting the results.