Clinical trials involve research conducted on humans to evaluate the effectiveness and safety of medical treatments. There are two main types of clinical trials: those that compare specific treatments to other treatments or no treatment, and those that observe existing treatments. Clinical trials are conducted in phases, with Phase I trials testing safety on small groups, Phase II trials evaluating effectiveness on larger groups, and Phase III trials confirming effectiveness on large groups. Phase IV trials study treatments after market approval to obtain additional risk and usage information.

1. A GUIDE TO UNDERSTANDING
CLINICAL TRIALS
Created by
(PART 1 – THE BASICS)

2. Topics covered
PART 1 – THE BASICS
What are clinical trials?
Types of clinical trials
Phases of clinical trials

3. What are clinical trials?
Clinical trials involve research conducted on humans that is
designed to evaluate the effectiveness of a drug or treatment and
add to medical knowledge
Source: A young researcher's guide to a clinical trial. Available from http://www.editage.com/insights/a-young-
researchers-guide-to-a-clinical-trial (Accessed March 07, 2016)

4. Clinical trials as defined by NIH*
*NIH: National Institutes of Health, USA
Source: What are clinical trials? Available from http://www.nhlbi.nih.gov/studies/clinicaltrials (Accessed
March 07, 2016)
Clinical trials are research studies that explore whether
a medical strategy, treatment, or device is safe and
effective for humans. These studies also may show
which medical approaches work best for certain
illnesses or groups of people.

5. Human subjects volunteer
to participate
Last for about 5-7 years
*First, a new medical strategy, drug, treatment, or device is developed in the lab, then it is tested on animals, and
finally tested on humans to see how safe or effective it is.
Approval of relevant
governing and ethical
committees is essential
Usually medical or clinical
studies
Constitute the last
step of the research
process*
Investigations are carefully
conducted following a pre-
determined research
protocol
Characteristics of clinical trials

6. Types of clinical trials
Clinical trials could be of two types:
• Specific treatments or interventions are given to the
participants by the investigators.
• The outcomes are then compared to a group that has been
given a different treatment or no treatment.
• The investigators or the researchers observe the treatments or
management techniques that are given to a group of patients
and note the outcomes.
• The researchers do not give the interventions.
1/2

7. More trials types defined by the NIH
Test new treatments,
combinations of drugs, surgical
approaches, or radiation therapy
Find ways to prevent diseases;
include medicines, vaccination,
or lifestyle change
Test the best way to detect
specific diseases or health
conditions
Come up with better tests or procedures
for diagnosing a disease or health
condition
Explore ways to improve the comfort and quality
of life of people with a chronic illness (also known
as supportive care trials)
2/2

8. Phases of clinical trials
Clinical trials are conducted in several phases and each phase has a different purpose.
PHASE I TRIALS
A new drug or treatment is tested on a small
group of people (20–80)
Purpose
To evaluate its safety and identify the side
effects, and to obtain early signs of
effectiveness
PHASE II TRIALS
The drug or treatment is given to a larger
group of people (100–300)
Purpose
To evaluate its effectiveness and obtain more
information about the side effects and risks
of the treatment
PHASE III TRIALS
The drug or treatment is administered to
very large groups of people (1,000–3,000)
Purpose
To confirm its effectiveness, compare it with
other modes of treatment, and evaluate the
overall risk-benefit equation
PHASE IV TRIALS
These studies are conducted after the drug’s
approval and launch in the market (also
called post-marketing surveillance studies)
Purpose
To obtain additional information about its
risks, benefits, and optimal use

9. END OF PART 1
We hope you found this useful. Here’s a list of topics we will
cover in Part 2:
• Protocols to be followed
• Informed consent from subjects
• Approval for trials
• Registration of trials
• Reporting guidelines for trials
• Manuscript structure of a clinical trial

10. www.editage.com/insights
@EditageInsights
Connect with us
For more useful resources and tips on publication, visit our website: