Problems with toxicity studies in the assessment of new drugs

The development of new medicines requires a lot of time and the efforts of many researchers. One of the most taxing parts of this endeavor is the need for long-term toxicity studies in different animals. This paper describes the development of two different medicines: zimeldine, an antidepressant, and omeprazole, a compound that acts against a specific enzyme in the gastric mucosa that is necessary for the production of gastric acid. Zimeldine was launched in the international market but had to be withdrawn when it caused severe unexpected adverse reactions. Omeprazole has been marketed successfully after a prolonged development phase characterized by difficult problems with the toxicity studies. Against the background of these two descriptions, this article questions the rationale for the present rules for long-term toxicity studies and emphasizes the need for leaders in the pharmaceutical industry to have a solid scientific background in order to be able to decide whether to abandon a project.