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Clinical study

Clinical trials are research studies aimed at testing new therapies, vaccines, drugs or diagnostic procedures for their safety and efficacy. Clinical trials are divided and conducted in different phases. Before an investigational drug is tested on a human in Phase I, it is first analyzed in the laboratory and then tested on animals.

  • Phase I: The number of participants is limited to a minimum and the aim of the study is to gain knowledge about the actual effect, compatibility and safety of the compound on the human body. Side effects are recorded in their variety and intensity.
  • Phase II: The number of subjects is increased to 20-300 with the intention of analyzing and comparing initial evaluations of different dosages and associated treatment efficacy. Phase II studies are often repeated several times with different subject groups to determine the safest treatment procedure and indication as a result.
  • Phase III: The subject group in Phase III is the largest with 300 to 3000 participants and focuses on demonstrating drug efficacy and safety. Often the final therapeutic approach is compared to already established procedures. In this phase, the dosage and administration are determined to be applied in the market in the future based on the clinical results.
  • Phase IV: Phase IV is used to monitor and gather information on long-term effects of the compound after market approval. Efficacy and safety will be continuously monitored and rare side effects documented.


Clinical trials are often the safest and fastest way to develop appropriate treatments, as a large amount of information can be obtained about efficacy and risks during the different phases in different people.

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Sven J. Kolthof



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