What types of clinical trials are there

Glossary entry

Brief description of the clinical study phases:

Phase 0
Examination of human material, e.g. tissue samples, determination of biomarkers. In certain cases, studies on humans, e.g. to assess new therapeutics and imaging diagnostics. These tests are carried out with sub-therapeutic doses (microdosing). First results in the field of pharmacokinetics and pharmacodynamics.

Phase I.
The drug to be tested is being used for the first time in humans on a small number of healthy volunteers or on a carefully defined patient population (for certain indications for which testing with healthy volunteers is not possible, e.g. cancer or /) under controlled conditions in order to obtain preliminary data about tolerability, pharmacokinetics and pharmacodynamics.

Phase II: Therapeutic Exploration
The drug to be tested is administered to a limited number of patients who, if indicated, are believed to have an effect. The therapeutic dosage framework is defined and the effectiveness, side effects and clinical toxicity are determined. This study phase is often divided into Phase IIa and Phase IIb: Phase IIa studies are clinical pilot studies that primarily evaluate drug safety, while Phase IIb studies examine the efficacy, in particular the dosage range and safety.

Phase III: Therapeutic Confirmation
The drug is tested in large-scale studies that focus on effectiveness and safety. These studies are required for the submission of the new drug for product licensing to regulatory authorities. Sometimes Phase III studies are divided into Phase IIIa and Phase IIIb: Phase IIIa studies are conducted after the drug has been shown to be effective, but before it is submitted for product licensing. Phase IIIb studies are studies carried out during phase III that can be used by marketing to further promote the drug once it has been approved in the market.

Phase IV: Therapeutic application
Phase IV studies are carried out after a drug has been approved for marketing. The studies are limited to the approved indication, dosage sizes, dosage form and patient population of the drug