Donepezil HCl(Aricept) is a selective and effective AChE inhibitor for bAChE and hAChE (IC50: 8.12/11.6 nM).

AChE (bovine):8.12 nM, AChE (human):11.6 nM

[3H]-Pyrilamine binding to histamine (H1) receptors in guinea pig cerebellum membranes.: Antagonists are incubated with guinea pig cerebellum membranes (0.6 mg/ml) and [3H]-pyrilamine (1.2 nM) in 0.5 ml 50 mM PBS, pH 7.5, for 30 min at 25 ℃. The incubation is ended by the addition of 5 ml of ice-cold PBS containing 2 μM pyrilamine and the collection of membranes on Whatman GF/B filters. Then the filters are washed with 3 × 5 ml of ice-cold PBS plus 2 μM pyrilamine and transferred to counting vials. The radioactivity retained by each filter is measured by liquid scintillation counting in 3 ml of HiSafe 3. Specific binding is determined from the difference between the [3H]-pyrilamine bound in the absence and in the presence of a large molar excess (10 μM) of unlabeled promethazine.