To understand Phase 4 clinical trials, we must first ask a foundational question:
The
Phase 1: When a clinical trial begins, a new drug is tested on a few people. All people in a Phase 1 trial receive the drug, usually in small doses. This type of trial is designed to determine safe doses of the drug, how different doses are tolerated, any potential drug side effects, and drug efficacy.
Phase 2: The drug is given to larger treatment groups, up to around 100 or so. Sometimes, the drug is compared to another treatment option. The goal is to see if the drug is effective enough to be tested in much larger groups of people.
Phase 3: Next, the drug will be studied in an even larger population (sometimes thousands). During Phase III studies, if a drug can improve over the standard treatment and is determined to be safe, it’s likely to be approved by regulatory authorities. Last year, out of more than 11,000 drugs that reached a pre-clinical stage,
After these phases, a medicine reaches Phase 4, which occurs after it receives regulatory approval. Phase IV studies (also known as post-marketing surveillance trials) play a key role in the clinical research continuum.
Sometimes, this phase also looks at how the drug works in patients with certain characteristics or to compare/combine the treatment with other drugs.
The
Phase 4 trials are often conducted as observational studies, so researchers don’t actively control the treatment participants receive. Instead, they observe how patients take the medication according to the current medical practice. The idea is for researchers to exert as little influence as possible and to study the medication under real-life conditions.
Other types of Phase 4 clinical trials include randomised controlled trials. In this type of trial, participants are randomly assigned to an experiment group (which receives the medication being tested) and a control group. There are also registries, which are observational and record patient data in real-world settings.
When designing and executing a Phase 4 clinical trial, it’s crucial that the trial results in valuable and actionable efficacy data.
To achieve this, considerations might include:
Recruiting a large and diverse participant pool (including those with a specific condition and healthy volunteers)
Observing how the drug functions in real-world scenarios in the general population
Maintaining patient engagement through a long-term follow-up process
Phase 4 clinical trials have several key components, including pharmacovigilance. Also called PV, this refers to a drug safety reporting system that monitors drug effects, keeping a particularly close eye on suspected adverse drug reactions or safety “signals,” which can include rare side effects.
Other aspects of Phase 4 clinical trials include real-world evidence and a broad patient population. By observing patients like these under normal clinical use conditions, clinical trials gather evidence essential for understanding a drug's long-term efficacy and implications.
As with all trials, Phase 4 trials have eligibility and exclusion criteria that determine who can participate in the study.
Executing successful, safe, and accurate Phase 4 clinical trials can present unique challenges. For example, recruiting a large and diverse patient population can be difficult. Likewise, maintaining patient compliance (particularly over long periods of time) can be a hurdle.
Managing and analysing the often massive datasets generated by real-world studies can also be challenging. This requires sophisticated techniques and systems to ensure data is stored, assessed, and acted on appropriately.
Phase 4 clinical trials have many regulatory requirements and ethical considerations specific to post-marketing research. Firstly, regulatory authorities play a critical role in overseeing these trials. They ensure these trials adhere to strict ethical and scientific guidelines, protecting participants from risk.
Like earlier trials, informed consent is a cornerstone of ethical research in Phase 4 clinical trials. Patients must be fully informed about the study’s objectives, potential risks and benefits, and their right to withdraw at any time.
Other ethical considerations include patient welfare, respect, participant privacy, and data confidentiality (which must be meticulously protected throughout the study).
Phase 4 clinical trials can significantly impact medical practice and patient care. For a recent success story, we can look at the results from a
This trial was the first-ever clinical trial conducted exclusively in Black and Hispanic/Latinx people with relapsing multiple sclerosis. Importantly, it set a new standard for inclusive research in MS.
Each clinical trial phase is designed to safely and effectively answer questions about how a drug performs. Phase 4 clinical trials play a critical role in collecting data on drugs that have been approved for the market: they allow us to understand their benefits, any previously undetected risks, and how they can best be used to treat patients (especially over a long period). This ultimately allows us to foster better healthcare outcomes and enhanced quality of life for many.
If you’re a patient seeking active Phase 4 clinical trials to contribute to this important element of healthcare innovation, visit our
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