Wirkungsweg

Wirkungsweg is a German term used in biology, medicine and pharmacology to describe the sequence of events by which a stimulus, such as a drug, hormone or other signaling molecule, produces a biological effect. The word combines Wirk-, meaning effect, with Weg, meaning path or route. In everyday scientific and clinical language, the Wirkungsweg refers to the chain from the initial interaction with a molecular target through intracellular signaling to the final cellular response and, in many cases, to broader physiological outcomes.

In pharmacology, the Wirkungsweg is often called the mode of action of a drug. It includes target binding, activation or inhibition of receptors or enzymes, subsequent signal transduction cascades (second messengers, kinases), and resulting changes in cellular function, such as altered metabolism, secretion or contractility. Pharmacokinetics, by contrast, describes how the body handles the drug, while the Wirkungsweg explains what the drug does to the body.

Wirkungswege can be straightforward, with a single receptor and linear signaling, or complex, involving multiple pathways, feedback loops and cross-talk between networks. This complexity can affect the onset, intensity and duration of effects, as well as potential interactions with other substances.

In modern biology and medicine, the term is increasingly supplemented or replaced by more specific terms like signal path or signaling pathway (Signalweg). Nonetheless, Wirkungsweg remains a practical, general concept for communicating mechanisms of action to students, clinicians and patients.