Have you ever wondered how a new medicine goes from being something scientists discover in a laboratory to a treatment that a doctor can prescribe? Before any medicine reaches patients, it goes through a long and carefully controlled process to make sure it is both safe and effective. This process involves years of research, testing, and strict checks to protect patients at every step.
Understanding The Drug Development Pathway
Developing a new medicine takes many years of careful research to make sure it is both safe and effective. Before treatment becomes available to patients, it goes through several important stages, including laboratory research, animal testing and clinical trials in humans.
Before Clinical Trials: Laboratory and Animal Research
Before a medicine is ever tested on people, scientists spend years studying it in the laboratory.
First, the medicine is tested in “in vitro” studies, which means experiments done outside a living organism (for example, in test tubes or cell cultures). These studies help researchers to understand how the medicine works.
If results are promising, the next step is “in vivo” studies, where the medicine is tested in animals. These are also called pre-clinical (or non-clinical) trials and are strictly regulated and approved by ethics committees.
At this stage, researchers assess:
- Safety – Is the medicine harmful?
- Effectiveness – Does it work as expected?
- Mechanism of action – How does it affect the body?
- Pharmacokinetics – How the body absorbs, distributes, breaks down, and removes the medicine
Many potential medicines do not progress beyond this stage if they are not effective or show concerning side effects.
If a medicine shows sufficient promise in pre-clinical studies, it can move on to testing in humans. These are called clinical trials and must be approved by regulatory authorities and ethics committees.
Clinical Trials in Humans
If a medicine shows sufficient promise in pre-clinical studies, it can move on to testing in humans. These are called clinical trials and must be approved by regulatory authorities and ethics committees.
Clinical trials are conducted in several phases, each designed to answer specific questions about the medicine.
Phase I: First Studies in Humans
Phase I is the first stage in which a medicine is tested on people. It usually involves a small group of participants, primarily healthy volunteers who do not have the condition. In some studies, patients may also be included in Phase I studies, depending on the disease being targeted – for example, in cancer research, where treatments may have stronger side effects.
During this phase, researchers start with very low doses and gradually increase them to identify the maximum tolerated dose and observe any adverse reactions. Participants are monitored closely throughout, and the data collected helps determine whether it is safe to proceed to the next phase. The main goal of Phase I is to assess the safety and tolerability of the medicine. Researchers also study pharmacokinetics (how the body handles the medicine: absorption, distribution, metabolism and excretion) and pharmacodynamics (how the medicine works in the body).
Phase II: Testing in Patients
In Phase II, the medicine is tested on a larger group of people (approximately 100 subjects), who have the disease that the medicine is intended to treat. In phase II, the medicine is studied in real patients, rather than healthy individuals, to assess the therapeutic effect of the medicine. Researchers also continue to evaluate safety and look for any side effects that may not have appeared in Phase I.
This phase often explores different doses and treatment schedules, and the results help determine whether a larger, confirmatory trial is justified.
Phase III: Testing Efficacy in a Large Group of Patients
During phase III, the medicine is tested on a large group of patients to confirm the effect of the medicine and to get a more detailed view on possible side effects. Usually, this phase includes up to a few thousand participants and lasts several years. These trials are often randomised and controlled, meaning participants are randomly assigned to receive either the new medicine or a comparison treatment (such as a placebo or existing standard of care). This is done so that any difference in outcome can be attributed to the medicine itself rather than other factors, such as age or health status.
Phase III provides the most robust evidence of efficacy and safety, and a successful outcome is typically required before a medicine can be submitted for regulatory approval.
Phase IV: Post-marketing Surveillance
Phase IV starts after the medicine obtained a marketing authorisation. At this point, the medicine has been proven to be safe, and effective, and the dose has been determined. The aim of this phase is to optimise the use of medication and detect any possible adverse effects from a real-life practice – for example, in patients who are being treated with multiple medications.
These studies can involve hundreds of thousands of patients across diverse populations, providing insights that were not possible in the more controlled earlier phases. Phase IV may also explore new indications, age groups, or long-term effects, helping to continuously improve how the medicine is used in clinical practice.
The Importance of Clinical Research
Clinical trials are the heart of modern research – without them, we would not have the treatments we use on a daily basis. However, behind every approved medicine are trial participants who made it possible.
By joining a trial, volunteers help bring the next breakthrough treatments and play a crucial role in shaping the future of medicine. Your participation can make a real difference – not just for you, but for other patients in the future.
Explore current clinical studies you may be able to take part in and see how your involvement could help advance new treatments: https://britishresearchpanel.co.uk/clinical-trials/