Phases of Clinical Research

OVERVIEW

• Phases of clinical research are the steps taken to gather evidence to determine whether a novel intervention or treatment is safe and effective for clinical use
• primarily refers to the process of clinical drug development, which begins with the process of drug design and discovery, but is applied more widely to other medical interventions
• for drugs, the entire process may take 10-20 years and cost over $1 billion
• published studies may not adhere strictly to the phase designations

PRECLINICAL TRIALS

• in vitro and in vivo animal studies
• assess efficacy, toxicity and pharmacokinetics in non-human models
• “proof of concept” and hypothesis generating from the point of view of the practicing clinician

PHASE 0 CLINICAL TRIALS

• “first in human” studies
• administration of single sub-therapeutic doses of the study drug to a small number of subjects (<20)
• gather preliminary data on pharmacodynamics and pharmacokinetics in humans
• may also refer to exploratory trials and pilot studies for Phase 1 trials

PHASE 1 CLINICAL TRIALS

• test a new biomedical intervention for the first time in a small group of people (e.g. 20-100)
• evaluate safety (e.g. determine a safe dosage range and identify side effects)
• usually involves healthy volunteers

PHASE 2  CLINICAL TRIALS

• study an intervention in a larger group of people (several hundred)
• determine dose requirements and efficacy (whether it works as intended)
• further evaluate safety
• involves healthy volunteers and/or patients
• may be case series or randomised controlled trials

PHASE 3  CLINICAL TRIALS

• study the efficacy of an intervention in large groups of trial participants (from several hundred to several thousand)
• compare the intervention to other standard or experimental interventions (or to non-interventional standard care)
• monitor adverse effects and collect information that will allow the intervention to be used safely

PHASE 4  CLINICAL TRIALS

• post-marketing surveillance studies
• monitor the effectiveness of the approved intervention in the general population
• collect information about rare adverse effects associated with widespread use over longer periods of time
• may or may not be mandated by regulatory bodies