Preclinical evaluation is a key step in the development of new drugs and therapies. In this article, we will focus on two key types of preclinical testing: in vitro and in vivo.

   In vitro studies

  The term "in vitro" comes from Latin and literally means "in glass." In the context of biomedical research, in vitro studies take place outside of a living organism, usually in a test tube or petri dish, and use cells or tissue as models of biological systems.

  In vitro studies are often the first step in preclinical evaluation. They allow potential drugs to be tested in a controlled environment, allowing scientists to determine exactly how a substance affects cells or tissues.

   In vivo studies

  The term "in vivo" also comes from Latin and means "in the living." In vivo studies are those conducted on living organisms, usually animals such as mice, rats or rabbits.

  In vivo studies give scientists the opportunity to understand how a potential drug works at the level of the whole organism. In vivo studies can examine how a drug is absorbed, distributed, metabolized and excreted by the body (pharmacokinetics), how it affects the body (e.g., changes in behavior, physiological parameters), as well as its toxicity and efficacy.

   Differences between in vitro and in vivo studies

  Although in vitro and in vivo studies are both key parts of preclinical evaluation, there are important differences between them.

   Complexity: In vitro studies are typically simpler and less expensive to conduct than in vivo studies. In vivo studies are more complex because they involve the entire organism and can be influenced by many factors, such as diet, age, gender, genetics, etc.

   Biological background: In vitro studies can provide very precise data on the interaction between a potential drug and a specific biological target. In vivo studies, on the other hand, provide information on the interaction of a drug with the biological systems as a whole, which is more similar to the clinical situation.

   Results: In vitro studies usually provide faster results, but in vivo studies are often considered more authoritative because they reflect the situation throughout the body.

   Summary

  In vitro and in vivo studies are key components of preclinical evaluation, each providing a unique set of information. In vitro studies provide detailed, controlled data at the cellular and tissue level, while in vivo studies provide a holistic view of how a drug works throughout the body. Both methods are essential to fully understand the safety and efficacy of new drugs.