Phases of Clinical Trials

What are Clinical Trials?

A clinical trial is a medical research study carried out with human subjects, with the intention of promoting medicinal therapy, expanding therapeutic options and developing medicines with ever better efficacy and safety. Furthermore, they are intended to understand as accurately as possible what are the properties, effects and the adverse reactions and side effects exerted by the active substance intended for curative purposes.

Clinical trials can be classified several ways, one of which is classification according to the study phase. From the phases detailed below, this early phase (phase I) is more experimental in nature, while in later phases, the focus shifts more and more towards curing the patients:

Phase I clinical trial: it is usually carried out in healthy volunteers in order to assess the tolerability and relative safety (innocuity) of the investigational product. In this phase, a small number of subjects is enrolled, who receive the treatment in a delayed manner, while the side effects and the bodily processes are closely monitored.

Phase I/II if it would be unethical to administer the investigational product to healthy volunteers, or if it would be useless in small quantities in terms of outcome (like, for example, in case of antitumor agents), real patients can (and should) be enrolled even in the first phase instead of healthy volunteers.

Phase II clinical trial: this is the first instance when the investigational product is administered to a small, carefully selected patient population with the specific disease. The aim of this study is to determine the appropriate dosing (which is expected to be effective and appropriately safe)

Phase III clinical trial: carried out with a larger number of patients, these studies are intended to provide additional evidence that the investigational product is safe to use, as well as to demonstrate therapeutic efficacy. Usually, this trial phase is carried out at a number of study sites in several countries, in a uniform manner and at the same time. These are frequently designed as comparative trials with available medicinal products already in use for the routine management of the specific disease. In this phase, several study arms might be applied, which means that the patients are randomly assigned to different treatment schemes. Data from patients treated on different study arms are compared upon the evaluation of the trial. In case of a so-called “double blind study”, during the study, neither the investigator nor the patient will know which treatment scheme is administered to the patient. This ensures reliability of the collected data. Following the phase III clinical study, if the results were favorable results, the product can undergo authority evaluation and decisions can be made on its commercial marketing.

Phase IV clinical trial: these studies are carried out with an already marketed medicinal product, which are intended to further investigate its risk-benefit rate, to clarify dosing and to detect less frequent adverse reactions.

Non-interventional trialEssentially, this means data collection where patients take the medicinal product and/or undergo the necessary diagnostic tests according to the standard of care, meanwhile certain data regarding their use of medication (or, possibly, a diagnostic method) are collected and analyzed. This can be performed pre-planned or subsequently, using database analysis. Anonymity and protection of personal data is ensured in this case, just like in any other study phases.

A separate kind of studies are those carried out with medical devices.

Instruments classified as medical devices may only be granted marketing authorization if their safety, efficacy and effectiveness. Research studies with “devices” are intended to serve this purpose. For example, medical devices may be instruments used for the prevention, diagnosis or treatment of a disease/injury, devices related to fertility control, devices for the administration of medicinal products, or diagnostic products which contain a medicine or an ingredient derived from human blood.