Drug Development and Clinical Trials

Key points

• • A new drug is first studied in the laboratory and in animals (preclinical testing) to check for basic safety and activity before any human is given it.
• • Phase I trials usually give the drug to a small number of healthy volunteers to check safety and how the body handles it, though toxic drugs such as some cancer drugs are first tested in patients.
• • Phase II trials give it to a small group of patients with the disease, to see whether it works and to find a suitable amount to use.
• • Phase III trials test it in large numbers of patients, often against a dummy (placebo) or an existing treatment, to prove it works and is safe.
• • Approval usually follows phase III, though some drugs reach patients earlier through accelerated or conditional pathways; phase IV is the ongoing watch for rare effects after marketing.
• • Good trials are typically randomised and controlled, and blinded where feasible, so that neither chance nor expectation gives a false result.