What are Clinical Trials?
Clinical trials are studies performed with
human volunteers to test new drugs or
combinations of drugs, new approaches to
surgery or radiotherapy or procedures to
improve the diagnosis of disease and the
quality of life of the patient
Different Phases of Clinical Trials:
Clinical trials are also 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.
Phase 0 is a recent designation for exploratory, first-in-human
trials conducted in accordance with the U.S. Food and Drug
Administration’s (FDA) 2006 Guidance on Exploratory
Investigational New Drug (IND) Studies. Phase 0 trials are also
known as human micro dosing studies and are designed to speed
up the development of promising drugs or imaging agents by
establishing very early on whether the drug or agent behaves in
human subjects as was expected from preclinical studies. and
pharmacodynamics (how the drug works in the body.
Distinctive features of Phase 0 trials include the administration
of single sub therapeutic doses of the study drug to a small
number of subjects (10 to 15) to gather preliminary data on the
agent’s pharmacokinetics (how the body processes the drug)
A Phase 0 study gives no data on safety or efficacy, being by
definition a dose too low to cause any therapeutic effect. Drug
development companies carry out Phase 0 studies to rank drug
candidates in order to decide which has the best PK parameters
in humans to take forward into further development. They
enable base go/no go decisions to be based on relevant human
models instead of relying on animal data, which can be
unpredictive and vary between species.
Clinical trial: Phase I
The first studies in humans are Phase I
trials. They are performed with small numbers of patients or
healthy volunteers and are used to answer questions such as
what dose of the drug is likely to be effective and what side
effects might occur.
Clinical trial: Phase II
The trials with larger numbers of patients and focus on how well
the treatment or procedure works, perhaps in particular situations
or groups of patients.
Clinical trial: Phase III
The trials enroll large numbers of
patients and are used to compare the effectiveness and safety
of the new treatment with that of the standard existing
treatment. Information obtained from large Phase III trials that
demonstrates the benefits a new drug over the existing
treatments are presented to regulatory authorities in order to
obtain a licensee to market and sell the drug.
Phase IV trial is also known as Post Marketing Surveillance
Trial. Phase IV trials involve the safety surveillance
(pharmacovigilance) and ongoing technical support of a drug
after it receives permission to be sold. Phase IV studies may be
required by regulatory authorities or may be undertaken by the
sponsoring company for competitive (finding a new market for
the drug) or other reasons (for example, the drug may not have
been tested for interactions with other drugs, or on certain
population groups such as pregnant women, who are unlikely to
subject themselves to trials).
The safety surveillance is designed to detect any rare or longterm adverse effects over a much larger patient population and longer time period than was possible during the Phase I-III
clinical trials. Harmful effects discovered by Phase IV trials may
result in a drug being no longer sold, or restricted to certain uses:
recent examples involve cerivastatin (brand names Baycol and
Lipobay), troglitazone (Rezulin) and rofecoxib (Vioxx).
Processes used to assign
participant to one group.
Study design and instructions to be followed
Participants do not know if in
experimental or control group.
Participants AND staff do
not know group assignment
Placebo: Inactive pill w/ no therapeutic value
Why some participate in Clinical Trials?
Give back to society
Exhausted all other treatments
Health care services
Payment & incentives