Anticholinergic agents for Parkinson's disease

Examples

Generic Name	Brand Name
benztropine mesylate
biperiden hydrochloride	Akineton
orphenadrine citrate	Norflex
procyclidine hydrochloride
trihexyphenidyl hydrochloride

How It Works

Anticholinergic medicines block nerve impulses (cholinergic nerve impulses) that help control the muscles of the arms, legs, and body. They also restrict the action of acetylcholine, an important chemical messenger in the brain (like dopamine) that helps regulate muscle movement, sweat gland function, and intestinal function.

For normal motor or muscle control, the effects of acetylcholine and dopamine need to be carefully balanced. When dopamine levels are low (as they are in people who have Parkinson's disease), a chemical imbalance results, causing symptoms such as tremor and rigid muscles. Anticholinergic medicines decrease levels of acetylcholine to achieve a closer balance with dopamine levels.

Why It Is Used

Anticholinergics may be useful in treating people younger than 70 with Parkinson's disease whose main symptom is tremor. People with slowness, stiffness, and balance problems, and people without tremor usually do not benefit from these medicines. Anticholinergics also may be useful in controlling drooling.¹

Anticholinergics usually are not used in people older than 70 or people who have developed mental impairment, such as memory problems, because these people are more likely to have severe side effects such as confusion and hallucinations (seeing or hearing things that aren't really there).¹

People who have certain medical conditions may require closer monitoring while they are taking anticholinergic medicines. These conditions include:

• Glaucoma.
• Problems with the digestive system, including severe constipation.
• Enlarged prostate or obstructions in the prostate.
• Myasthenia gravis.

How Well It Works

Anticholinergics are still used for some people, especially for the treatment of tremor and drooling.¹

Side Effects

Side effects from anticholinergics are very common and may include:

• Dry mouth.
• Blurred vision.
• Constipation.
• Nausea.
• Inability to urinate.
• Decreased sweating.
• Fast heartbeat (tachycardia).

Side effects on the central nervous system (brain and spinal cord) are more common in older people and are often a reason to stop using the medicine. These side effects include:

• Sleepiness.
• Memory problems.
• Confusion.
• Hallucinations (seeing or hearing things that aren't really there).

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Anticholinergics are the oldest of the medicines used to treat Parkinson's disease symptoms. Today they have a limited role in the treatment of Parkinson's because more effective medicines that cause less severe side effects have become available. Anticholinergics are often used early in the disease to lessen tremor, but they are rarely tolerated by older people because of their numerous side effects.

People who take anticholinergics need to be careful while driving or performing other tasks that require alertness because these medicines may impair mental and physical abilities.

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Author:	Douglas Dana Monica Rhodes	Last Updated: February 12, 2007
Medical Review:	Anne C. Poinier, MD - Internal Medicine E. Gregory Thompson, MD - Internal Medicine Colin Chalk, MD, CM, FRCPC - Neurology
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