Anticholinergics

Anticholinergics are older drugs, less commonly prescribed these days, that can have a mild effect on the symptoms of Parkinson's by blocking the action of the chemical messenger acetylcholine.

These are:

• trihexyphenidyl (Broflex, Artane, Agitane)
• benztropine (Cogentin)
• orphenadrine (Disipal)
• procyclidine (Kemadrin, Arpicolin).

Anticholinergics are often prescribed alone, especially in the early stages before levodopa is necessary, although they are also used in conjunction with levodopa or amantadine. Trihexyphenidyl, orphenadrine and procyclidine are available in liquid form.

Advantages

They can be useful for younger people in the early stages of Parkinson's when symptoms are mild. They tend to improve tremor more than slowness and stiffness. Anticholinergics may also be used to reduce saliva production when drooling is a problem and to damp down bladder contractions that can cause a strong, frequent urge to urinate.

Disadvantages

Confusion, a dry mouth, constipation and blurring of vision can occur. They are not usually prescribed to older people with Parkinson's because there is an increased risk of confusion as well as memory loss, and in men, urinary hesitancy. Also, anticholinergics may interfere with levodopa absorption in the small bowel. This can reduce the effectiveness of Sinemet or Madopar.