Firstly, potential therapeutics are extensively tested pre-clinically in cells and animal models. Only the most effective drugs proceed into human studies.
Clinical drug development is conducted in different phases:
- In phase I the safety, side effects and the characteristics of the drug are assessed. These small studies are usually conducted in healthy volunteers, unless this is not possible for the specific type of drug.
- Phase II studies are performed in patients with a specific disease. These are still small-scale studies and the focus is on safety, but also looking into the effectiveness of the drugs. They are often performed in an open label setting (meaning that each patient and investigator knows whether it is receiving the therapy or not) and the intervention is compared to non-treated patients or patients receiving standard treatment.
- Phase III is the pivotal phase. In this phase a large study is conducted, often in a double-blind, placebo-controlled setting. This means that the active compound is compared to a placebo (non-effective) control and that both the patient and the researcher are unaware to which group the patient belongs. In this phase the effectiveness of the compound is studied in detail (safety continues to be monitored), to gather more information to apply for marketing approval.
- After regulatory approval drugs continue to be monitored for effectivity and safety in phase IV. This is often required by the regulators or decided by the study sponsor.
For observational studies these phases are usually not applicable.
Clinical trial participants
Trials have inclusion and exclusion criteria who can participate in the trial to ensure groups are comparable and thereby reliable results are obtained. These criteria are listed in the study protocol. A participant has to fulfil the inclusion criteria to be able to participate. Exclusion criteria disqualify the patient from participating.
Each trial requires informed consent. In this form objective information is given about the trial process, the potential risks and benefits.
Before participating in a clinical trial you should sign the inform consent for. You can first discuss this with your local doctor and asks for more information/explanation before signing.
Signing the informed consent form does not mean that you have to participate in or complete the trial. You have the right to withdraw at any time.
Participating in clinical trials
Before deciding to participate in a clinical trial you should carefully consider your options. Thoroughly read the details of the study protocol. Discuss the trial and alternatives with your local doctor. Feel free to ask all the questions you may have to your doctor and/or the research team. A list of questions that are good to discuss can be found here, but you may of course also have other questions.
More information on clinical trials can be found on https://clinicaltrials.gov/ct2/about-studies.