Galantamine: a new treatment for Alzheimer's disease.

Galantamine (Reminyl) is a tertiary alkaloid, originally isolated from the Caucasian snowdrop and several Amaryllidaceae plants. It has been used for over 40 years in anesthetics to reverse the effects of curarization. In vitro and in vivo studies have confirmed that galantamine is an orally-active, reversible, competitive inhibitor of brain cholinesterase, which is 50 times more selective for acetylcholinesterase, compared with butyrylcholinesterase. Galantamine has also been shown to allosterically potentiate sub-maximal nicotinic responses to acetylcholine. This direct effect on pre- and postsynaptic nicotinic receptors may represent a second mechanism of action for enhancing cholinergic function, but as yet it is unclear as to whether that has any clinical significance. Galantamine has been licensed for use in the symptomatic treatment of Alzheimer's disease patients, after proving its efficacy in a number of well-designed clinical trials. It has to be administered twice daily and has shown good tolerability, which typically for drugs of this class, is improved by slow titration. The most common side effects are: nausea, vomiting, diarrhea and anorexia. Galantamine appears to be an effective treatment for Alzheimer's disease comparable with the other acetylcholinesterase inhibitors in improving cognition and function with growing evidence for its effects on behavior and caregiver burden.