Cholinesterase Inhibition
Definition
The biochemical mechanism of organophosphate and carbamate toxicity: inhibition of the enzyme acetylcholinesterase prevents breakdown of acetylcholine at synapses, producing overstimulation of nervous tissue. Brain cholinesterase activity assay is the definitive test.
- Toxin class
- Organophosphates and carbamates
- Enzyme affected
- Acetylcholinesterase
- Effect
- Acetylcholine accumulates, synapse overstimulated
- Definitive test
- Brain cholinesterase activity assay
Common questions
Why is brain cholinesterase activity used as the definitive test rather than blood levels alone?+
Blood cholinesterase (plasma and red cell) can be affected by other factors and does not always track brain enzyme inhibition precisely, so a definitive postmortem confirmation of organophosphate or carbamate poisoning relies on direct measurement of brain tissue cholinesterase activity.
How does carbamate poisoning differ toxicologically from organophosphate poisoning despite the same enzyme target?+
Carbamates inhibit acetylcholinesterase reversibly and the enzyme regenerates spontaneously within hours, while organophosphates bind more permanently and often require reactivating antidotes, so the clinical course and window for measuring inhibition differ between the two classes.
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