Developing a new drug, such as an antiviral, takes 10 to 15 years and follows a strict series of stages designed to show that the drug is safe and effective.1. Discovery. Scientists identify a target, often a viral enzyme such as a protease. Candidate molecules are found by screening large libraries of chemicals or by rational drug design, using computer models of the target's 3D structure to design a molecule that fits its active site.2. Preclinical testing. The drug is tested on cells and tissues in the laboratory, and then usually on animals, to check how it works, whether it is toxic and what dose might be safe.3. Clinical trials in humans:
• Phase 1: a small group (about 20 to 100) of healthy volunteers. Tests safety, side effects and how the body handles the drug, starting with low doses.
• Phase 2: a few hundred patients with the disease. Tests whether the drug works, finds the best dose, and looks for side effects.
• Phase 3: thousands of patients. Compares the new drug with a placebo or the best existing treatment.Phase 3 trials are usually randomised (patients are placed in groups at random) and double-blind (neither the patients nor the doctors know who receives which treatment). This removes bias, and a placebo allows for the placebo effect. Large samples mean results can be tested statistically.4. Approval. A regulator, such as the MHRA in the UK, reviews all the data before the drug can be licensed.5. Phase 4. After release, post-marketing surveillance looks for rare side effects that only appear when millions of people use the drug.
• Phase 1: a small group (about 20 to 100) of healthy volunteers. Tests safety, side effects and how the body handles the drug, starting with low doses.
• Phase 2: a few hundred patients with the disease. Tests whether the drug works, finds the best dose, and looks for side effects.
• Phase 3: thousands of patients. Compares the new drug with a placebo or the best existing treatment.Phase 3 trials are usually randomised (patients are placed in groups at random) and double-blind (neither the patients nor the doctors know who receives which treatment). This removes bias, and a placebo allows for the placebo effect. Large samples mean results can be tested statistically.4. Approval. A regulator, such as the MHRA in the UK, reviews all the data before the drug can be licensed.5. Phase 4. After release, post-marketing surveillance looks for rare side effects that only appear when millions of people use the drug.