1. Mechanism of action: Echothiophate

1. Mechanism of action: Echothiophate is an organophosphate that covalently binds via its phosphate group to the serine-OH group at the active site of AChE. Once this occurs, the enzyme is permanently inactivated, and restoration of AChE activity requires the synthesis of new enzyme molecules. Following covalent modification of AChE, the phosphorylated enzyme slowly releases one of its ethyl groups. The loss of an alkyl group, which is called aging, makes it impossible for chemical reactivators, such as pralidoxime, to break the bond between the remaining drug and the enzyme.