Clinical pharmacokinetics of galantamine

Abstract

Galantamine is the most recently approved cholinergic drug for the treatment of Alzheimer's disease, the most common type of dementia. Vascular dementia and Alzheimer's disease with cerebrovascular disease are also common in older patients. Dementia affects cognition, causes losses in ability to perform activities of daily living and often results in the emergence of psychiatric and abnormal behavioural symptoms. Dementia also results in an ever-increasing burden and a decreased quality of life for caregivers. Treatments for dementia, particularly Alzheimer's disease, have focused on improving function in the cholinergic system. Vascular dementia and diffuse Lewy body dementia are also associated with significant defects in cholinergic function. Galantamine works by inhibiting acetylcholinesterase and by allosterically modulating nicotinic receptors. In clinical trials, galantamine has shown benefits in the domains of cognition, function in activities of daily living, and behaviour. Galantamine is about 90% bioavailable and displays linear pharmacokinetics. It has a relatively large volume of distribution and low protein binding. Metabolism is primarily through the cytochrome P450 system, specifically the CYP2D6 and CYP3A4 isoenzymes. Population pharmacokinetic modelling with galantamine has shown that the variables affecting clearance are age, sex, and bodyweight. Model simulations demonstrate the importance of a slower dose-escalation schedule in patients with moderate hepatic impairment. In several large trials, galantamine has been shown to be well tolerated, with most adverse events being mild-to-moderate and gastrointestinal in nature. Based on the literature and clinical trial experience, galantamine appears to be an excellent treatment option for patients with Alzheimer's disease, vascular dementia or Alzheimer's disease with cerebrovascular disease.