How are new drugs developed and tested?

New drugs are developed through a process of discovery and design, followed by preclinical and clinical testing.

The development of new drugs begins with the identification of a medical need, followed by the discovery or design of a potential drug. This often involves a detailed understanding of the disease at a molecular level. Scientists may use computer modelling to design new molecules, or they may discover new uses for existing drugs. Once a potential drug has been identified, it is synthesised and subjected to a series of in vitro (test tube) and in vivo (animal) tests to assess its safety and efficacy.

The next stage is preclinical testing, which involves rigorous laboratory and animal testing to determine whether the drug is safe to test in humans. This includes tests for potential side effects, toxicity, dosage levels, and how the drug is absorbed, metabolised, and excreted by the body. These tests must comply with strict regulations to ensure that they are both ethical and scientifically valid.

If the drug passes preclinical testing, it moves on to clinical trials, which are conducted in several phases. Phase I trials involve a small group of healthy volunteers and aim to assess the drug's safety, determine a safe dosage range, and identify side effects. Phase II trials involve a larger group of people who have the condition the drug is intended to treat. These trials aim to assess how well the drug works and to further evaluate its safety. Phase III trials involve large groups of patients in hospitals and clinics and aim to confirm the drug's effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug to be used safely.

Once a drug has successfully completed clinical trials, it can be approved for use by regulatory authorities such as the Medicines and Healthcare products Regulatory Agency in the UK or the Food and Drug Administration in the US. This involves a detailed review of all the testing data and may also involve post-marketing surveillance to monitor the effects of the drug in the wider population.