Jan 25

Before it can be released onto the market, any new medicine has to go through clinical trials to prove their efficacy and especially to show that they are safe for the public use. Clinical trials generally consist of a four phase study (Phase I-IV). It is important to remember that the meaning of “phase” is to be descriptive, and in no mean serves as a set of requisites. In addition, there is no implication of fixed order of what has to be studied as the typical development plan might be inapplicable for some drugs. Before we get inside the details of Phase I-II-III-IV of clinical trials, let’s see in what a phase consists first.

The development of a clinical trial follows a logical
and step-wise procedure. Clinical trials consist of four temporal
phases (phase I-IV). Each phase consists of a gathering of many
studies. Early studies are generally short and relatively small. The
information collected from those studies will be used to design the
next larger and more conclusive studies. Each study follow the
“Objectives → Design → Conduct → Analysis → Report” pattern.

Studies
A phase, in a clinical trial setting, consists of a gathering of “studies”.

Each study follows a similar pattern:

Objectives → Design → Conduct → Analysis → Report

The objectives represent the goals set for a particular study. For example, learning about the drug distribution in the human body, how long it takes before their excretion, pharmacodynamics, their side effects, are among the many possible objectives of a study.

The design represent how the study will look like and is planned by experts in the domain. The design always contains very specific instructions about every aspect of the test elements. Those instructions might, for example, involve time-points at which blood has to be drawn, how much blood needs to be drawn, time-points for urine collection, time-points for performing electrocardiograms or descriptive information of each test.

Conduct represents the act of running the study itself. For example, the act of drawing the blood, performing spirometry, doing an exercise test can all be part of the conduct of a study. Every study design has to be rigorously follow during conduct and every data collected as well as every procedure has to be documented.

Analysis represents the dissection and examination of the information collected. Analysis has to take in account every data and their results, but also any deviations to the protocols. Their results are a determinant to help decide the future outcome of the drug development and will be used to help decide what other steps are needed to complete the trial.

Report represents the summary and conclusions of the study. Using the results obtained by analysis, reports indicate what happens next. Accordingly to what the previous reports say, new studies with new objectives and designs might be investigated and conducted, and all new information collected and analyzed will be used to generate a new report.

Early studies
Clinical trials development follows a logical and step-wise procedure. The first studies done during a clinical trial are generally short and small (few centers, few subjects). The information collected from these early studies are critical to identify the profile of the new drug in order to sketch the next larger and more informative studies. Hence, these data allow to evaluate the new drug short-term safety and gives some preliminary insights of how well it is tolerated by the human body. Other information, such as PK and PD, is essential to determine what is the appropriate dosage and the proper scheduling to administer the new therapy.

Later studies and additional studies
Later studies are typically longer, larger and include a more varied population. Based on any new information collected, there is a possibility to add more studies. For example, finding of a severe side effect may suggest the need to do more non-clinical studies.
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References:
(1) International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH)
(2) Health Canada
(3) U.S. Food and Drug Administration (FDA)

For more information, visit http://www.clinical-trials-info.com/.

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