In vitro Inhibition of Human Plasma and Erythrocyte Cholinesterases by a Selected Drugs (Enzymes Inhibitors)

Abstract

The inhibitory effect for human plasma and erythrocyte cholinesterase activity by six drugs already known as an enzyme inhibitors (Cimetidine, Ciprofloxacin, Donepezil, Sildenafil, Erythromycin, and Chlorpheniramine) was tested in vitro. The affinity toward the cholinesterase system was evaluated by using different concentrations of the investigated drugs. The cholinesterase activities were determined by using the modified electrometric method. Each drug showed different ability to inhibit cholinesterase activity depending on its concentration and its selectivity to the either plasma or erythrocyte cholinesterase; only Donepezil and Chlorpheniramine showed higher inhibitory effect. Ciprofloxacin showed moderate inhibition of cholinesterase but still statistically insignificant. Cimetidine, Sildenafil and Erythromycin showed little inhibitory activity although they have a good inhibitory effect on the liver enzyme system Cytochrome P450 (CYP450 ).