The Basics Of Clinical Trial
All Focus On articles are contributed by
Ms Low Ai Lin
Senior Manager, Clinical Trials Office,
Division of Clinical Trials and Epidemiology, NCC

A clinical trial is a research study in human volunteers and involves interventions such as administration of drugs or use of a medical device for the purpose of answering specific health-related questions. Carefully conducted clinical trials are the safest and fastest way to find treatments that work in people and new ways to improve health.

Trials are organized into different phases of research, in order to build up a greater understanding of the new treatment, before it is approved or recommended for routine use. The development of new drugs begins in the laboratory. Promising substances from invitro experiments then enter an extensive animal-studies phase to investigate the substance’s possible effects and safety profile. Should the desired effects occur, the required toxicity studies are begun in order to eventually test the substances in humans. Once the pre-clinical program has advanced so far that there is an understanding about the substance’s properties – both positive and negative, applications are submitted to relevant authorities to obtain approval to carry out the first test on humans i.e. to begin clinical trials.

There are four main phases of clinical trials.

PHASE 1 comprises the first trials on humans. These are performed on healthy volunteers and are mainly intended to establish the tolerable dosage interval for humans. The investigations also study if and how the drug is absorbed, metabolized and excreted from the body. One exception from using healthy volunteers in Phase I may be with trials involving very toxic drugs like chemotherapy.

PHASE II generally follows, if Phase I studies show that the substance may be given to humans in reasonable doses and without overly troubling adverse reactions. These are the first studies on patients having the disease intended for treatment and are meant to discover the minimum and maximum effective doses. The purpose is to extensively investigate how the drug behaves in the patients’ bodies, which effects can be measured, and how these effects relate to a given dose, and so on. An effort is generally made to enroll as homogenous patients as possible because there is uncertainty about the drug’s possible effects and it is desirable to hold the number of possible confounding factors to a minimum. Once Phase II is completed, there should be a good understanding about the drug’s effects, suitable doses, and a preliminary understanding about the adverse reaction profile. After which Phase III follows.

PHASE III studies are designed to document the drug’s effects and adverse pattern in a wider patient pool that is more representative of the population in which the study treatment is intended. These studies include patients of various ages, patients with concurrent diseases, patients who are taking concurrent medication etc. When Phase III program is complete, it is possible to begin talking about the drug’s properties and common side effects in a relatively representative cross-section of patients with some certainty, and the necessary documentation for getting the drug registered should now be available.

PHASE IV