10 Things That You Should Probably Know About Anticholinergic Drugs for Parkinson’s Tremor
Pope John Paul II, PWP But His Age Would Have Made Poor Candidate for Anticholinergics
Anticholinergic drugs are very different from the other medications prescribed for Parkinson’s, most of which have some effect on dopamine or dopamine receptors. These on the other hand block the effects of the brain neurotransmitter chemical acetylcholine.
The dopamine deficiency of Parkinson’s somehow makes the basal ganglia of the deep brain that regulate movement, overly-sensitive to acetylcholine. The result is a misfiring in this region and the production of oscillating loops of inappropriate activity, some at exactly the same rate as the tremor. The anticholinergics block this by correcting the oversensitivity to acetylcholine. Thus, they are very effective at treating the tremor of Parkinson’s except that in older patients with dementia or a predisposition to it, blocking acetylcholine can worsen the dementia and even cause frank disorientation. Here are 10 things that you should probably know about anticholinergics (trihexyphenidyl (Artane) and benztropine (Cogentin)):
- They are “old” drugs, off patent for many years. The result is that there’s not a big profit margin so they’re not promoted by pharmaceutical firms and unfortunately possibly underutilized for tremor in younger PD patients.
- As described they should probably not be given to anyone well over 60, with significant cognitive decline or with actual dementia because they could worsen it and even cause disorientation.
- Their effect on the bladder is to cause urine retention, especially bad for elderly men, most of whom already have urinary difficulties from an enlarged prostate.
- They should not be taken if you have closed-angle glaucoma of the eyes.
- They can cause their own fine tremor in both hands.
- They block the body’s parasympathetic autonomic nervous system causing constipation, dry mouth, and visual focusing difficulties.
- This parasympathetic effect causes blocking of sweat gland activity, potentially very dangerous in heavy exercise in heat because the body without the ability to sweat cannot regulate high temperature situations.
- Despite all this they have a longstanding record of safety over many years.
- They can cause sedation, bad if you already suffer from EDS (excessive daytime sleepiness).
- If you overdose on them there’s a cool poem recited by medical students and medical residents who work in the emergency department because so many poison plants if eaten cause an anticholinergic crisis: Hot as a Hare, Red as a Beet, Blind as a Bat, Mad as a Hatter, Dry as a bone and the bladder and bowel lose their tone.
"Mad as a hatter"
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