What Are Anticholinergics?

Anticholinergics are a class of medications that are used to treat the symptoms of Parkinson’s disease (PD), particularly the tremor that is characteristic of PD. Anticholinergics were the first pharmaceutical drugs used to treat PD, but they are not as effective in alleviating the motor symptoms of the condition compared to other treatments like carbidopa-levodopa therapy and dopamine agonists. Anticholinergics may be used as an additional treatment to help relieve the tremor of PD. They may be particularly useful in early stages of Parkinson’s when symptoms are mild.1,2

How anticholinergics work

The motor symptoms of PD are caused by the reduction in dopamine, a neurotransmitter (chemical messenger) that transmits signals in the brain to produce smooth, purposeful movement. As PD damages and destroys the neurons (nerve cells) that produce dopamine, the motor symptoms of PD appear. Although the primary treatments for PD are those that directly affect dopamine, anticholinergics provide a different mechanism of action to treat the symptoms of PD. Anticholinergics block the action of acetylcholine, another neurotransmitter involved in messages from the brain to the muscles. It is believed that by blocking the receptor for acetylcholine, anticholinergics increase the activity of neurons responsible for movement in the basal ganglia. Anticholinergics are frequently used in combination with other treatments for PD.1,2

Formulations of anticholinergics

Two anticholinergics that are used in the U.S. to treat PD are Cogentin® (benzotropine mesylate) and Artane® (trihexyphenidyl). Cogentin comes in a tablet and an injectable form, although the tablet is most often used for people with PD. Artane comes in a tablet and an elixir.3-5

Side effects of anticholinergic drugs

Each medication has its own set of possible side effects; however, there are some common side effects that are seen among all anticholinergics. Common side effects experienced by people taking anticholinergic medications include blurred vision, dry mouth, constipation, and urinary retention, or difficulty urinating. Older people (over the age of 70) on anticholinergics are more susceptible to confusion, hallucinations (seeing or hearing things that are not real), and dementia.3

It is important to talk with your health care provider before starting or stopping any new treatments, including over-the-counter medications and alternative treatments.

Additional therapy

Anticholinergics are just one category of drugs that are used in the treatment of PD. There are several other types of treatment for the symptoms of PD, including carbidopa-levodopa therapy, dopamine agonists, monoamine oxidase-B (MAO-B) inhibitors, and surgery for deep brain stimulation. Each person with PD experiences a highly individual set of symptoms and progression of the disease. Treatments are determined based on the individual’s symptoms and how they respond to different medications.6

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Written by: Emily Downward | Last reviewed: November 2020