Transferability of animal test results to humans

1. Introduction

In pharmaceutical research, animal experiments take place in the preclinical phase of the long path that leads to a market- ready medicine. It usually takes many years to reach this stage. Researchers generally test hundreds of thousands of substances before they find one with the potential to inhibit or positively influence the course of a particular disease. At first, the experiments in this journey of discovering new active pharmaceutical ingredients (APIs) involve solutions and cell cultures. Animal experiments only take place once certain conditions have been fulfilled. They are used to determine how the drug candidate is metabolised by the organism and if it produces detrimental effects. Only when a substance has successfully completed all the prescribed preclinical trials – in other words, once it has been shown to be safe and effective in cell cultures and animal experiments – can it be tested in clinical trials in humans. Why only then?