When a research group or drug company develops a new medication or treatment, the process starts in a laboratory with test tubes and animal studies. These studies give researchers an idea of how much potential this medication has, highlighting how it works and what kind of side effects it might have in humans.
If the results of early drug studies look good, the researching company or organisation designs and pays for clinical trials to test the medication in humans. These trials are divided into three stages, which are know as Phase I, Phase II, Phase III , and Phase IV trials.
| Phase I | Phase II | Phase III | Phase IV | |
| Question | Is the treatment safe? | Does the treatment work? | What are the long term results or effects in large numbers | |
| Risk Level | Riskiest - First in man trials used to determine best doses | Moderate Risk - Some safety information about the drug is known | Lowest Risk - More information is known about safety & how well it works | |
| Length of Trial | Shortest - A few weeks to a few months | Medium - Usually at least 6-12 months | Long - May last as long as 2 - 3 years or more | |
| Number of Participants Involved | A few participants only | About one hundred - two hundred participants | At least several hundred people |