Clinical trials are tightly regulated by laws, which were made to protect participants, while ensuring that the drug in development will not be released for use as a patient treatment until it is safe and effective.
These trials are advanced in steps, each of which has to be successful in order to move on to the next phase - see phases I to IV below:
- Phase I trials determine how safe a compound is in healthy volunteers (looking out for potential undesired side effects).
- Phase II trials determine safety and the optimal dose in patients (the amount of the compound and how often it should be taken).
- Phase III trials determine the compound’s effectiveness in patients.
- Phase IV trials may be performed after the drug is already licensed and usually look for the effect of the drug outside the limited specifications of earlier clinical phase trials.
Each phase trial must show that it was successful in order to move on to the next phase trial.
Due to the complexity of these processes, it typically takes years from early development to marketing of a drug. In this process, many compounds fail to demonstrate effectiveness or for other reasons their development may be stopped.
More information on how drugs are developed may be found in EUPATI- European Patients' Academy