galantamine

Galantamine is an oral medication used to treat patients with Alzheimer's disease. Galantamine is in a class of drugs called cholinesterase inhibitors that also includes tacrine (Cognex), donezepil (Aricept), and rivastigmine (Exelon). Cholinesterase inhibitors inhibit (block) the action of acetylcholinesterase, the enzyme responsible for the destruction of acetylcholine. Acetylcholine is one of several neurotransmitters in the brain, chemicals that nerve cells use to communicate with one another. Reduced levels of acetylcholine in the brain are believed to be responsible for some of the symptoms of Alzheimer's disease. By blocking the enzyme that destroys acetylcholine, galantamine increases the concentration of acetylcholine in the brain, and this increase is believed to be responsible for the improvement in thinking. Galantamine was approved by the FDA in 2001. (The brand name of galantamine was changed in 2005 from Reminyl to Razadyne.)

Razadyne, Razadyne ER

GENERIC AVAILABLE: No

Yes

The most frequent side effects seen with galantamine are:

• nausea,
• vomiting,
• diarrhea, and
• anorexia (weight loss).

These side effects generally occur during the beginning of treatment or when the dose is increased. These side effects typically are mild and temporary. Taking galantamine with food and ensuring adequate fluid intake may reduce the impact of these side effects.

Other important side effects include:

• headache,
• abdominal pain,
• fatigue,
• slow heart rate,
• depression,
• sleepiness and
• fainting.

Galantamine tablets are taken twice daily, preferably with the morning and evening meals. Most often, galantamine therapy is started with the lowest dose, 4 mg twice daily for several weeks, and then continued at 8 to 12 mg twice daily. The recommended dose when using extended release capsules is 8 to 24 mg once daily in the morning.

Drugs with anticholinergic properties and which cross into the brain, such as atropine, benztropine (Cogentin), and trihexyphenidyl (Artane) produce opposite effects to (counteract) galantamine and should be avoided during therapy with galantamine. Drugs such as ketoconazole (Nizoral, Extina, Xolegel, Kuric)and paroxetine (Paxil) that reduce the activity of liver enzymes that break down galantamine may increase blood levels of and, therefore, the side effects of galantamine. Galantamine may add to the neuromuscular blocking effect of succinylcholine and similar drugs that are used during surgical anesthesia. Unlike donepezil (Aricept), galantamine does not increase blood levels of other medications and increase their risk for side effects.

Studies in pregnant rats and rabbits using galantamine at high doses failed to show effects on the offspring; however, no studies have been performed in pregnant women. Therefore, physicians must weigh the potential benefits against the potential risks of galantamine before prescribing it for pregnant women.

It is not known if galantamine is secreted in breast milk.

What preparations of galantamine are available?

Tablets: 4, 8, and 12 mg. Extended release capsules: 8, 16, and 24 mg. Oral solution: 4 mg/mL.

How should I keep galantamine stored?

Tablets and liquid solution should be stored at room temperature, 15-30 C (59-86 F).