Medications and Drugs

Pharmacy Author: Emmanuel Saltiel, Pharm. D.
Medical Editor: Jay Marks, M.D.

GENERIC NAME: rivastigmine

BRAND NAME: Exelon

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), donezepil (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.

PRESCRIPTION: Yes

GENERIC AVAILABLE: No

PREPARATIONS: Capsules: 1.5 mg (yellow), 3 mg (orange), 4.5 mg (red) and 6 mg (orange and red).

STORAGE: Capsules should be stored at room temperature, below 25°C (77°F).

PRESCRIBED FOR: Rivastigmine is used for the treatment of mild to moderate dementia of the Alzheimer's type.

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, often 1.5 mg twice daily, and gradually increased not more than once every 2 weeks. The goal usually is 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.

DRUG INTERACTIONS: Drugs with anticholinergic effects and which cross into the brain, such as atropine, benztropine (Cogentin), and trihexyphenidyl (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: About one-half of patients who take rivastigmine become nauseated, 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.

Reference: FDA Prescribing Information

Last Editorial Review: 10/19/2003 4:54:47 PM

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