Title: inhibitor
Long Title: IUPAC Gold Book - inhibitor
DOI: 10.1351/goldbook.I03035
Status: current

Definition
A substance that diminishes the rate of a chemical reaction; the process is called inhibition. Inhibitors are sometimes called negative catalysts, but since the action of an inhibitor is fundamentally different from that of a catalyst, this terminology is discouraged. In contrast to a catalyst, an inhibitor may be consumed during the course of a reaction. In enzyme-catalysed reactions an inhibitor frequently acts by binding to the enzyme, in which case it may be called an enzyme inhibitor.

Related Terms
- catalyst: https://goldbook.iupac.org//terms/view/C00876
- effector: https://goldbook.iupac.org//terms/view/E01901
- inhibition: https://goldbook.iupac.org//terms/view/I03034

Source
- PAC, 1993, 65, 2291. 'Nomenclature of kinetic methods of analysis (IUPAC Recommendations 1993)' on page 2295 (https://doi.org/10.1351/pac199365102291)

Related Reference
- PAC, 1991, 63, 1227. 'Manual on catalyst characterization (Recommendations 1991)' on page 1244 (https://doi.org/10.1351/pac199163091227)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/I03035/html
- json: https://goldbook.iupac.org/terms/view/I03035/json
- xml: https://goldbook.iupac.org/terms/view/I03035/xml

Citation: Citation: 'inhibitor' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.I03035
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Accessed: 2026-05-01T09:54:59+00:00