direktevirkende

Direktevirkende is a Danish term used in pharmacology and medicine to describe substances whose effects arise from a direct interaction with a biological target, such as a receptor, enzyme, ion channel, or transporter. In this sense, the drug acts directly on the intended site of action rather than through intermediate processes.

The concept is often contrasted with indirektevirkende (indirect-acting) agents, whose effects depend on intermediary mechanisms. Indirect-acting substances may promote the release of endogenous mediators, inhibit the breakdown of these mediators, or otherwise modulate signaling pathways without binding directly to the final receptor or enzyme.

Examples of direktevirkende actions include direct-acting vasodilators that relax vascular smooth muscle by acting on the vessel wall, and direct-acting receptor agonists such as epinephrine or phenylephrine that stimulate specific receptors directly. By comparison, indirect-acting agents such as amphetamine increase synaptic levels of norepinephrine rather than binding to receptors in a straightforward manner.

The term serves as a descriptive tool to categorize mechanisms of action and does not denote a formal pharmacological class. Some drugs exhibit both direct and indirect effects depending on dose, context, or formulation, and in practice the distinction can overlap with broader pharmacodynamic concepts like receptor agonism or enzyme inhibition. Beyond medicine, the phrase may occasionally appear in related fields to describe direct interactions between chemicals and biological targets.