BRAND NAME: Cognex
DRUG CLASS AND MECHANISM: Tacrine is an oral medication used to treat patients with Alzheimer's disease. Tacrine is in a class of drugs called cholinesterase inhibitors that also includes rivastigmine (Exelon), donezepil (Aricept), and galantamine (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 tacrine. Tacrine was approved by the FDA in 1993.

PRESCRIPTION: Yes

GENERIC AVAILABLE: No

PREPARATIONS: Capsules: 10, 20, 30, and 40 mg.

STORAGE: Capsules should be stored at room temperature, 15-30癈 (59-86癋).

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

DOSING: Tacrine is usually taken four times a day on an empty stomach (one hour before, or two hours after meals). The doctor may increase the dose gradually if liver tests are normal. (See side effects, below.) However, the dose is usually not more than 40 mg four times daily.

DRUG INTERACTIONS: Drugs with anticholinergic properties and which cross into the brain, such as atropine, benztropine (Cogentin), and trihexyphenidyl (Artane) produce opposite effects of tacrine and should be avoided during therapy with tacrine.

Unlike donezepril (Aricept), tacrine does not reduce the elimination of other drugs, increasing their levels in blood and the likelihood of their side effects.

PREGNANCY: Animal reproduction studies have not been done with tacrine. It is not known if tacrine causes fetal harm when taken by a pregnant woman

NURSING MOTHERS: Tacrine may pass into breast milk and be harmful to the nursing infant; it should not be used while nursing.

SIDE EFFECTS: The most common side effect of tacrine is an increase in a liver test called alanine aminotransferase (ALT) as a result of liver damage. When a patient starts taking tacrine, blood is drawn on a weekly basis to measure ALT. If there is an increase in blood ALT, the dosage of tacrine can be reduced. Other side effects of tacrine include nausea, indigestion, vomiting, diarrhea, abdominal pain, and skin rash.