rivastigmine, Exelon

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GENERIC NAME: rivastigmine

BRAND NAME: Exelon, Exelon Patch

DRUG CLASS AND MECHANISM: Rivastigmine is an oral medication used to treat patients with Alzheimer's disease. Rivastigmine is in a class of drugs called cholinesterase inhibitors that also includes tacrine (Cognex), donepezil (Aricept), and galantamine (Razadyne - formerly known as Reminyl). 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, rivastigmine increases the concentration of acetylcholine in the brain, and this increase is believed to be responsible for the improvement in thinking seen with rivastigmine. For most patients who take rivastigmine, there will not be a dramatic improvement, but the progression of symptoms may be slowed. After six months of treatment with rivastigmine, 25%-30% of patients scored better on tests of memory, understanding, and activities of daily living as compared with only 10%-20% of patients receiving placebo (a dummy or sugar pill). Rivastigmine was approved by the FDA in 1998.



PREPARATIONS: Capsules: 1.5, 3, 4.5, and 6 mg. Solution: 2 mg/ml. Patch: 4.6mg/24 hours, 9.5 mg/24 hours

STORAGE: Capsules and solution should be stored at room temperature, 15-30 C (59-86 F).

PRESCRIBED FOR: Rivastigmine is used for the treatment of mild to moderate dementia of the Alzheimer's type or mild to moderate dementia associated with Parkinson's disease.

DOSING: Rivastigmine usually is taken twice daily with meals. Due to gastrointestinal side effects that can be seen early in therapy, rivastigmine therapy is generally started at a low dose.

For treating dementia associated with Alzheimer's the starting dose is 1.5 mg twice daily. It is gradually increased no more than once every two weeks. The goal usually is 3 to 6 mg twice daily. If a patient develops severe gastrointestinal side effects such as upset stomach and vomiting, he or she may need to stop taking rivastigmine for a few doses and then start taking it again at the same dose or a lower dose.

The starting dose for treating dementia associated with Parkinson's disease is 1.5 mg orally twice daily. The dose may be increased every four weeks to 3 to 6 mg twice daily. When using the patch the recommended starting dose is 4.6 mg/24 hours patch once daily. The patch should be replaced with a new one every day. The maximum dose is one 9.5 mg/24 hour patch. At least four weeks should elapse before increasing the dose.

DRUG INTERACTIONS: Drugs with anticholinergic effects and which cross into the brain, such as atropine, benztropine (Cogentin), and trihexylphenidyl (Artane) oppose the effects of rivastigmine and should be avoided during therapy with rivastigmine. Unlike donepezil (Aricept), rivastigmine does not cause the blood levels of other medications to rise and increase their risk for side effects.

PREGNANCY: Studies in pregnant rats and rabbits with high doses of rivastigmine failed to show effects on the offspring; however, no studies have been performed in pregnant women. Therefore, physicians must weigh the potential benefit of prescribing rivastigmine to pregnant women against the potential risks to the fetus.

NURSING MOTHERS: It is not known if rivastigmine is secreted in breast milk.

SIDE EFFECTS: The most common side effects are nausea, vomiting, and weight loss. About one-half of patients who take rivastigmine develop nausea, and about one-third vomit at least once, most commonly during the first few weeks of treatment as the dose is slowly increased. Between one in five and one in four patients lose weight during rivastigmine therapy (about 7 to 10 pounds, on average). One in six patients experiences a loss of appetite. About one in fifty patients develops dizziness. Overall, 15% of patients (between one in seven and one in six) discontinue therapy due to side effects. Seizures, decreased heart rate, low blood pressure, fainting, and depression also have been reported.

Reference: FDA Prescribing Information

Last Editorial Review: 6/22/2012

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