Galantamine hydrobromide is a derivative of the natural product galantamine, and is used to treat symptoms of early and moderate Alzheimer’s disease. One model for the action of this disease is that the amount of the neurotransmitter acetylcholine is limited, negatively affecting memory and learning. Treatment with anticholinesterase, an inhibitor of the enzyme that breaks down acetylcholine, should then help to increase the amount of acetylcholine in the brain and limit symptoms. Several types of anticholinesterases have been used commercially for this purpose, among them galantamine hydrobromine. Some medical personnel consider this class of drugs to be ineffective at treating the symptoms of Alzheimer’s disease.
The alkaloid galantamine was originally derived from a folk medicine made from the bulbs of Galanthus woronowii and various other genera, including Narcissus. Research was conducted in the 1950s in the Soviet Union, and this compound was isolated, identified, and used to treat various disorders of the central nervous system. The drug can now be made synthetically and, having been formulated as galantamine hydrobromide, is marketed as an Alzheimer’s disease medication.
Galantamine hydrobromide inhibits the breakdown of acetylcholine, a neurotransmitter that is important for factors that decrease in an Alzheimer’s patient. Involved in learning and memory, the amount of this compound is thought to be limited in the brains of people with this disease. Treating patients with a drug that limits the breakdown of acetylcholine was hypothesized to cause an increase in the amount of the neurotransmitter in the brain, and thus limits the symptoms of Alzheimer’s disease. An advantage of galantamine is that it is competitive and reversible, so it is not lethal like anticholinesterases such as snake venoms or poison gas.
It is very important that a patient be started at the lowest dose of galantamine hydrobromide and then have the amount increased very gradually. The drug is only meant to affect the symptoms and does not lessen the progression of the disease. It may take up to three months to see any effect. Individuals may vary in how they are affected by this drug.
There are large differences in the way in which some people metabolize galantamine hydrobromide. Most of the drug’s metabolism takes place in the liver, and a small percentage of the population are so-called slow metabolizers. They take much longer to degrade the Alzheimer’s disease drug because they lack a particular type of drug metabolizing enzyme. The dosage of drug is titrated for each person.
The side effects of galantamine hydrochloride can be quite unpleasant, and primarily consist of vomiting and nausea. Modifying the patient’s diet can help mitigate these effects. The severity of the side effects and the small degree of improvement has led some doctors to conclude that anticholinesterase therapy is not warranted. Current models of pathology focus on the beta amyloid plaques that form in the brain.