Clinical trials are carried out by medical research organizations and charities who need to test developments in drugs and medical procedures before taking them any further or putting them on the market. Medical trials are heavily regulated and they are only carried out once the drug or device in question has passed safety tests and gains the approval of a health authority and/or ethics committee so as not to put any of its human testers in danger, though as with any treatment, there still remains some degree of uncertainty. The participants in drug trials are typically volunteers, though most trials offer considerable payment to fulfil their research needs as quickly and efficiently as possible. There are different volunteer requirements for each trial, depending on what kind it is, and so not any old person can sign up to do one. These strict entry conditions are put in place because, for accuracy, the participants in each trial need to be as similar to each other as is humanly possible. Trials are expensive, time-consuming and - in a sense - urgent all at once, so precision is key. For basic Phase 0 or Phase 1 drug trials, potential volunteers must undergo a medical screening in order to take part. Unless their results are positive and fit the needs of the trial co-coordinator, they won't be able to partake as it is essential that the testers are at a level of health appropriate for that particular study to get accurate results and avoid discrepancies that could put the entire trial in jeopardy.
Tests carried out in a medical screening typically include:
- Blood sampling
- Drug abuse testing
- Weight and height measurement
- Measure of blood pressure, heart rate and temperature
- Urine sampling
- Measurement of the electrical activity of the heart
- Pregnancy testing (only applicable to women).
This medical screening is carried out for all clinical trials, but for the aforementioned drug trials the volunteer's eligibility generally depends entirely on it, while others have additional requirements or specifications.
Most other trials look for patients and volunteers who have a particular disease or medical condition, so different rules apply. These trials are carried out by patient organizations and charities focusing on finding treatments and solutions to things such as cancer, multiple sclerosis and arthritis, each trial having varying entry conditions. Because of the nature of the disease and its many different kinds, cancer trials are complex and contain variants from study to study, as doctors and researchers usually focus on a single type of cancer to find out what does or does help to treat it.
Personal GP's are generally consulted prior to going into a trial, and they can advise against participating for any number of reasons. Other factors that influence eligibility into any clinical trial can include age, medical treatments currently being undergone, the particular stage of the participant's condition or over-subscription.