What are the four phases of a clinical trial?

Though there is sometimes a phase 0 to test whether researchers were correct about the way the body reacts to a drug, often clinical trials will start at phase I. A clinical trial refers to a study within clinical research where patients are monitored to determine the efficacy of a treatment; this can be a drug, medical device or procedure. Therefore, from the very first stage, a clinical operations team will be testing to see how the drug is broken down by the body, looking for side effects and beginning to find the optimal dosage.

Phase I ranges between several months to a year and tests the treatment on a small group of healthy patients. Once the trial is complete the drug safety associate (DSA) will submit their research to the regulatory agency at which point the FDA reports that around 7 in 10 receive approval.

Those drugs, wearables or other treatments that pass approval at the first stage of clinical trials will progress to phase II where the focus is to test on a larger sample and typically introduce a placebo group. The placebo group - usually a randomised sample - will receive an inactive drug or a dummy treatment which allows clinical research associates (CRAs) to identify whether patients show side effects because they believe they’re receiving the treatment. Researchers can then compare the effectiveness of the treatment against the placebo group to get a clear picture of how well it works.

At this stage, clinical trial assistants (CTAs) are also assessing the safety of the treatment and monitoring any short-term adverse effects and phase II will normally span two years. The FDA reveals that the success rate at this stage is just 33%.

At phase III, a clinical trial manager will work alongside the project manager to identify if the drug has an overall positive effect on the patient’s wellbeing. Having qualified to this stage CRO companies will recruit more patients into randomised groups to get a clearer picture of data discrepancies and therefore understand the success of the drug.

Treatments which receive approval after phase III are awarded a licence meaning that the medicine can go to market and be prescribed to the public. Over the last 10 years, US drug manufacturers have spent on average $1 billion getting their drug to market and this is partially due to rising costs associated with advancements in technology.

Read more on why you should be a project manager.

The fourth and final stage is tested once the drug has gone to market and is designed to understand the side effects better and establish if there are any long-term risks throughout the life span of the drug. At phase IV DSAs are evaluating the outcomes on a more wide-spread basis – generally in the thousands.

At ICON, we’re determined to be the partner of choice in drug development and this ambition sees us working on an extensive variety of projects. For more insight read about the impact of Covid-19 on pharmacovigilance.