Cholinesterase inhibition by phenothiazine and nonphenothiazine antihistaminics: Analysis of its postulated role in synergizing organophosphate toxicity
Several antihistaminic compounds inhibit in vitro pseudocholinesterase (ChE) from several sources (human, rat, or horse plasma), pI50 ranging from 5.0 to 6.0. This inhibition is competitive with acetylcholine (ACh) and is reversible. Acetylcholinesterase (AChE) from rat brain was nonsensitive to ant...
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| Autores principales: | , , |
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| Formato: | JOUR |
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_0041008X_v31_n2_p179_Fernandez |
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| Sumario: | Several antihistaminic compounds inhibit in vitro pseudocholinesterase (ChE) from several sources (human, rat, or horse plasma), pI50 ranging from 5.0 to 6.0. This inhibition is competitive with acetylcholine (ACh) and is reversible. Acetylcholinesterase (AChE) from rat brain was nonsensitive to antihistaminics even at a concentration of 4 mm. Antihistaminics do not compete with either organophosphates or quaternary ammonium compounds in inhibiting ChE. Inhibition of ChE by antihistaminics is more pronounced at alkaline pH values than at acidic or neutral pH. Administration of promethazine ip to rats at a dose of 50 mg/kg resulted in a 90% inhibition of ChE 1 hr later, while the AChE was totally nonsensitive to the inhibitor even when the dose of the antihistamine was doubled. Results were analyzed in relation to the postulated role of ChE inhibition in antihistaminic potentiation of organophosphorus intoxication. © 1975. |
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