Pharmaceutical drug development process. It takes 8 to 20 years to launch a drug from the date of its molecule invention.
Clinical trials are divided into four phases. Each phase presents a separate clinical trial, and it might be required to carry out multiple studies within the same phase for drug authorization. A drug will receive a marketing authorization if it passes the first three trial phases successfully. Phase IV trials are post-authorization studies.
Purpose: to study tolerability, pharmacodynamics, and pharmacokinetics.
How do drug trials work? First, preclinical trials are conducted on biological models and animals. They are followed by Phase I clinical trials.
In Phase I trials, an investigational drug is first used in a small group of healthy volunteers to assess its safety, determine the safe dose range, and identify side effects. The volunteers are closely monitored according to the results of numerous tests and examinations. The concentration of the investigational drug in the bloodstream is also evaluated. Drugs with a known toxic effect (for example, chemotherapy drugs) can be readily investigated in a group of subjects in whom the expected benefits of their use exceed the known risks. Phase I trials enroll about 30 to 50 people and usually take several weeks to complete. Their results show if it's possible to move to Phase II trials in a particular therapeutic area.
Purpose: to test the efficacy with certain indications
In Phase II trials, an investigational drug is administered to a larger number of people suffering from a particular disease or disorder to determine its efficacy and further evaluate its safety. The main goal is to make sure that the expected therapeutic effect is achieved. Efficacy and safety are evaluated against a placebo. Often one of the objectives of a trial is to select the optimal drug dose or regimen. Such trials take several months to several years to complete, and their results show if it's possible to move to large-scale Phase III trials.
Purpose: to confirm the efficacy and safety of a test item in large populations.
Phase III trials enroll several hundred to several thousand people suffering from a respective disease or disorder. An experimental drug undergoes additional trials to evaluate its safety and efficacy further. Monitor side effects and adverse events, and compare it with commonly used drugs. A new drug's efficacy and safety are evaluated against standard therapy in conditions closely resembling actual clinical practice. Such trials' distinctive features include long-term follow-up and assessing the achievement of long-term effects and quality of life. Such trials take several months to several years to complete.
Phase IV trials are conducted to investigate the effects of a drug in special groups of subjects and a more comprehensive collection of safety data. Such trials take several months to several years to complete.