It has been proposed that the drugs Circe used were an extract from Datura stramonium (also known as jimsonweed), which causes memory loss and delirium. This would give a basis for the snowdrops use as an antidote, as Datura stramonium is anticholinergic, while galantamine is an acetylcholinesterase inhibitor. Medical uses
Galantamine is indicated for the treatment of mild to moderate vascular dementia and Alzheimers. In the United States, it is approved by the Food and Drug Administration as safe and effective for the treatment of mild to moderate dementia. As with other cholinesterase inhibitors, galantamine may not be effective for treating mild cognitive impairment.The FDA considers galantamine to have dual status as a prescription drug and as a OTC dietary supplement. Alzheimers disease
Alzheimers disease is characterized by the impairment of cholinergic function. One hypothesis is that this impairment contributes to the cognitive deficits caused by the disease. This hypothesis forms the basis for use of galantamine as a cholinergic enhancer in the treatment of Alzheimers. Galantamine inhibits acetylcholinesterase, an enzyme which hydrolyzes acetylcholine. As a result of acetylcholinesterase inhibition, galantamine increases the availability of acetylcholine for synaptic transmission. Additionally, galantamine binds to the allosteric sites of nicotinic receptors, which causes a conformational change. This allosteric modulation increases the nicotinic receptors response to acetylcholine. The activation of presynaptic nicotinic receptors increases the release of acetylcholine, further increasing the availability of acetylcholine.
Galantamines competitive inhibition of acetylcholinesterase and allosteric nicotinic modulation serves as a dual mechanism of action.To reduce the prevalence of negative side effects associated with galantamine, such as nausea and vomiting, a dose-escalation scheme may be used. The use of a dose-escalation scheme has been well accepted in countries where galantamine is used. A dose-escalation scheme for Alzheimers treatment involves a recommended starting dosage of 4 mg galantamine tablets given twice a day (8 mg/day). After a minimum of 4 weeks, the dosage may then be increased to 8 mg given twice a day (16 mg/day). After a minimum of 4 weeks at 16 mg/day, the treatment may be increased to 12 mg given twice a day (24 mg/day). Dosage increases are based upon the assessment of clinical benefit as well as tolerability of the previous dosage. If treatment is interrupted for more than three days, the process is usually restarted, beginning at the starting dosage, and re-escalating to the current dose. It has been found that a dosage between 16–24 mg/day is the optimal dosage. Available forms
The product is supplied in prescription form only in twice-a-day tablets, in once-a-day extended-release capsules, and in oral solution. Side effects
Galantamines side effect profile was similar to that of other cholinesterase inhibitors, with gastrointestinal symptoms being the most notable and most commonly observed. One study reports higher proportions of patients treated with galantamine experiencing nausea and vomiting as opposed to the placebo group.