Anticholinergic Drugs

man taking medication

Anticholinergics can be helpful for tremor and may ease dystonia associated with wearing-off or peak-dose effect. They have little effect on other symptoms of PD.

They do not act directly on the dopaminergic system. Instead, they decrease the activity of acetylcholine, a neurotransmitter that regulates movement. Potential adverse effects include blurred vision, dry mouth, constipation and urinary retention.

Additionally, research from the Parkinson’s Foundation’s Parkinson’s Outcomes Project has supported the finding that cognitive slowing is a side effect of anticholinergics. Older individuals are especially susceptible to confusion and hallucinations on anticholinergics, so these agents should be avoided in people older than 70.

Forms of Anticholinergics

Benztropine (Cogentin®)

Available Doses: 0.5 mg, 1 mg, 2 mg
Typical Treatment Regimen: 0.5–2 mg 2-3 times/day
Side Effects: Confusion, memory issues, hallucinations, dry mouth, blurry vision, urinary retention
Indications: Monotherapy or combination therapy, predominantly for tremor and dystonia in younger people; should be avoided in elderly. Can also be helpful in reducing the amount of saliva to treat excessive drooling due to the side effect of dry mouth.

Trihexyphenidyl HCL (formerly Artane®)

Available Doses:  2 mg, 5 mg tablets. 2 mg/5 ml elixir
Typical treatment regimen: 1–2 mg 2-3 times/day
Side Effects: Confusion, memory issues, hallucinations, dry mouth, blurry vision, urinary retention
Indications: Monotherapy or combination therapy, predominantly for tremor and dystonia in younger people; should be avoided in elderly. Can also be helpful in reducing the amount of saliva to treat excessive drooling due to the side effect of dry mouth.

Side Effects

  • Confusion
  • Hallucinations
  • Decreased short-term memory
  • Dry mouth
  • Blurry vision
  • Urinary retention

Quick Facts

  • Anticholinergics are the oldest class of medications to treat PD; they were first used in the 1900s
  • They can be used to reduce the amount of saliva is produced, and therefore can decrease drooling
  • Most helpful to younger patients with PD whose chief complaint is a tremor

Disclaimers:

* Please note that the side effects listed in the tables that accompany each class of medication are the most commonly experienced. Not all individuals will experience such side effects. For many people who do experience side effects, they can often be effectively limited or eliminated with careful adjustments to dosage or the timing of the individual doses.

Speak to the treating physician immediately if any side effects are experienced. For a complete description of each drug and its possible side effects, please request a “package insert” from your pharmacist for each drug used. It is recommended that all prescriptions be filled at the same pharmacy to avoid interactions between medications. Interactions can be dangerous and even life-threatening, so make sure the pharmacist knows of all medications and supplements being taken, including over-the-counter medications and supplements.

Caution: PD medications may have interactions with certain foods, other medications, vitamins, herbal supplements, over the counter cold pills and other remedies. Anyone taking a PD medication should talk to their doctor and pharmacist about potential drug interactions.

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