Understanding Clinical Trials, their Purpose, Eligibility Criteria & More

Clinical trials are generally medical research tests that involve people, the purpose of which is to find better ways to prevent, diagnose, screen for, or treat disease.


Since these are scientific studies, every step seeks to find answers to scientific questions. This is why clinical trials follow strict, scientific standards that are designed to protect patients and ensure reliable results.


In relation to the pharmaceutical industry, clinical trials are conducted to collect data that will help determine if a new drug or device under development is safe and efficient.


A new drug or device being developed is first tested with extensive laboratory research. Once laboratory research is successful and the Food and Drug Administration (FDA) gives its approval, human testing follows. And so clinical trials begin.


Clinical Trial Protocol

Every trial must have a study plan or protocol that describes what will be done at every stage and the various aspects that will be tackled.


  • What will be done during the clinical trial
  • How the clinical trial will be conducted
  • The necessity of every part of a clinical trial
  • Eligibility criteria for participants


How Participants Are Chosen

Different clinical trials have different eligibility criteria but the most common takes into account the certain type or stage disease that a group of people have, whether or not they received a certain kind of therapy, they belong in a certain age group, and their medical history and current health status.


The purpose of the eligibility criteria is to ensure that medical differences among participants are reduced, which is critical in acquiring reliable results. This is why interested participants have to go through medical tests to confirm their eligibility and to check whether or not they have health problems outside of the disease being studied.


Phases of Drug-Related Clinical Trial


Drug-related studies have four phases, with each one having a different purpose.


Phase I

This involves a small study group of healthy volunteers, between 20 and 100, to help evaluate the safety of the drug being tested and their side effects as dosage is increased. This phase usually lasts several months to complete and about 70% of experimental drugs move on to the next one.


Phase II

At this point, the experimental drugs’ efficacy and effectiveness are tested. Randomized trials are carried out where one group of patients receives the experimental drug while a second ‘control’ group gets a placebo or a standard treatment. Studies of this phase are often blinded, which means both patients and researchers do not know which group received an experimental drug.


Phase III

If phase II involves several hundred patients, phase III carries out trials of up to several thousands of patients. Large-scale randomized and blind tests are carried out for several years to acquire a more detailed understanding of the effectiveness, benefits, and risks of an experimental drug. Once completed, a pharmaceutical company can request approval for marketing the drug from the FDA.


Phase IV

This is the part of a drug clinical trial where the drug studied is already on sale. The ongoing research revolves around monitoring long-term effectiveness and to compare its cost-effectiveness against traditional therapies. Depending on the research findings, the drug or device can be taken off the market. In some cases, it is placed under restrictions.


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