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Pharmacology: Pharmacodynamics: Mechanism of Action: Alzheimer's disease is characterized by cholinergic deficiency in the cortex and basal forebrain, which contributes to cognitive deficits. Donepezil reversibly and noncompetitively, inhibits centrally-active acetylcholinesterase, the enzyme responsible for hydrolysis of acetylcholine. This appears to result in increased concentrations of acetylcholine available for synaptic transmission in the central nervous system.
Pharmacokinetics: Absorption: Well absorbed.
Distribution: Vdss: 12 to 16 L/kg.
Protein binding: ~96%, primarily to albumin (75%) and alpha1-acid glycoprotein (21%).
Metabolism: Extensive hepatic metabolism via CYP2D6 and 3A4 and glucuronidation to four major metabolites (two are active).
Half-life elimination: 70 hours.
Time to steady-state: 15 days.
Time to peak, plasma: Tablet, 10 mg: 3 hours.
Excretion: Urine 57% (17% as unchanged drug), feces (15%).
