New drugs go through various stages of development before an end product believed to bring something new to the health service is debuted. Clinical trials consist of distinct stages, each with its own objective; beginning with (the less common) phase 0, through to the optional post-licensing phase 4.
The following information outlines the process based on a clinical trial of a new cancer drug.
These involve just a few people and a small dose of the drug being trialled. Researchers are looking to see if the drug behaves in the human how they expect, based on lab studies.
Around 15-30 people take part in these small first phase trials. Researchers are looking at: effective dosage, side effects, and outcomes. Adaptive phase 1 studies are common as the results from one small group over a period of time is used to inform and tweak the original trial. This is a crucial part of the learning process, and something experts in the clinical trial field, such as http://www.richmondpharmacology.com/specialist-services/adaptive-phase-i-studies are well equipped to undertake.
Once a drug is established as safe for human use and as having some value, it moves to phase 2. The trials are larger than the previous phase, with up to 100 people taking part each time. At this point researchers are looking at further side effects, dosage, who responds well to the drug, and if the results warrant it being taken to the next level. Patients are often sorted into random groups, some receiving the real drug, and some a placebo. Neither staff nor patients will know which is which to ensure the results are not skewed.
These use large groups of patients and are intended to discover things such as if the new drug could be of more use, or have fewer side effects, than those currently available. Again, the participants are likely to be in different groups, with some trying the new option, and some using the old one. To be licensed most drugs need to have been involved in extensive phase 3 studies.
This is an optional stage, sometimes done to monitor long-term side effects, risks, benefits and outcomes. In this case many thousands of people will take part in the trials.