Clinical trials are research studies on human participants. They are conducted to collect data regarding the safety and the efficacy of a new drug or a medical device. Drug and device testing begins with extensive laboratory research, which can involve years of experiments in animals and human cells. Only after collecting enough data about the success of the initial laboratory tests, the investigators can continue with enrollment of volunteers and/or patients into small pilot studies, and subsequently conduct progressively larger scale comparative studies.
Each and every clinical trial must receive a regulatory body and ethics committee approval based on its risk/benefit ratio. Once approved, the trial is typically conducted in four phases, considered as a separate trials. Clinical trials may take place in one or in multiple centers (even in different countries). Clinical study design aims to ensure the scientific validity and reproducibility of the results.
Phase I
Studies the safety of a drug or device and it usually includes a small number of healthy volunteers, who are generally paid for participating in the study. The aim of the study is to determine the effects of the drug or device on humans including how it is absorbed, metabolized, and excreted. It also investigates the side effects that may occur. About 70% of experimental drugs pass this phase of testing.
Phase II
Studies test the efficacy of a drug or device within a larger group of people that allows to discover the less common side effects. Most phase II studies are randomized trials where one group of patients receives the experimental drug, while a second “control” group receives a standard treatment or placebo. Often these studies are “blinded” – neither the patients nor the researchers know who has received the experimental drug. About 30% of experimental drugs successfully complete both Phase I and Phase II studies.
Phase III
Studies involve randomized and blind testing in an even larger group of people than phase II and it can last several years. The aim is a deeper understanding of the effectiveness of the drug or device, the benefits, and the range of possible adverse reactions. 70% to 90% of drugs that enter Phase III studies successfully complete this phase of testing. Once Phase III is complete, a pharmaceutical company can request approval for marketing of the drug.
Phase IV
Studies or Post Marketing Surveillance Trials provide additional information, including the treatment’s risks, benefits, and optimal use. This phase is ongoing during the drug’s lifetime of active medical use.
As pointed out above, in some cases clinical trials may involve healthy volunteers with no pre-existing medical conditions, whereas in others they involve patients with specific health conditions who are willing to try an experimental treatment. The sponsor of a clinical trial may be a governmental organization or a pharmaceutical, biotechnology, or medical device company.
Certain functions, such as monitoring, management etc., may be managed by an outsourced partner, such as a contract research organization like IMR.