Anticholinergic Drugs | Easy Drug Card | Dr. Peter Rice



Anticholinergic Drugs | Drugs that can Influence Athletic Performance

I could hardly wait for Spring to arrive this year in Colorado. Our last frost day in Denver is typically in early May, but we’ve had snow into June or July, particularly in our mountains. I began biking to work shortly after I returned from Ireland in late May. It’s about 12 miles each way and it took a few days to get into the routine.

Last week we had some great biking days, at least in the mornings. I tend to be cold when temperatures are below 55°, so I love it when I wake up to a morning in the 60s. My problem has been the ride home in the evenings. I tend to enjoy my ride home when the temperature is less than 85°. But this is Denver, and although the lower humidity makes it a little more tolerable, our evening temperatures can approach 100°F.

Anticholinergic

Anticholinergic Drugs


Many who exercise, both professional and amateur athletes and the many folks who exercise to improve their health – all serious about their athletic performance – sometimes find themselves wondering if their medications are working for them or against them.

When I bicycle in other parts of the US, I make it a point to ask individuals who have high altitude experience about their view of heat and humidity as compared to altitude.  Without exception so far, heat and humidity beat out altitude. It is much harder to exercise when you are hot than when you are in a high altitude/lower oxygen environment.

If heat limits athletic performance, then drugs that inhibit sweating make it even worse.

Sweating occurs automatically when the core of the body exceeds a set temperature, and when the sympathetic nervous system is activated. In a previous blog I mentioned how beta-blocker drugs that block sympathetic nervous system activation can make it harder to exercise. Sweating is unusual in that it is not mediated by epinephrine/norepinephrine, but rather by the neurotransmitter acetylcholine. So drugs that block the response to acetylcholine – called anticholinergic drugs – inhibit sweating in addition to having other effects.  

There are a number of drugs that have anticholinergic activity.  

  • The older antihistamines, particularly diphenhydramine, have anticholinergic effects which dry a runny nose, but also inhibits sweating.
  • Older tricyclic antidepressants, such as amitriptylline are taken at bedtime to minimize their anticholinergic side effect of dry mouth; other antidepressants (doxepin, paroxetine, nortriptyline) also inhibit sweating.
  • Drugs for incontinence (oxybutynin, tolterodine), mood adjustment (clozapine, thioridazine, olanzapine and chlorpromazine) and gastrointestinal drugs (L-hyoscyamine) can produce anticholinergic effects as well.

These are not the only medicines with anticholinergic activity. Your pharmacist or physician can help you identify other medications and help you make good medication choices. Good decisions about medications requires individual medical information and history, and prescription medication changes should only be made with the approval of the prescriber.

If you are exercising while taking a medicine that has anticholinergic activity, you might consider choosing cooler times of the day and moderating your effort to avoid overheating. Most athletes, amateur, professional or just health-conscious, naturally slow down to avoid overheating.

There are also clothing options.  I use SkinCooler™ clothing from desotosport.com when I cycle in the heat, like biking across Kansas in the summer heat.  This high-tech clothing can be dampened with water and provides cooling independent from sweating.

About Dr. Peter J. Rice

Dr. Peter J. Rice is a professor of Pharmacology emeritus at the East Tennessee State University Quillen College of Medicine and Professor of Clinical Pharmacy at the University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences. --------------------------------------------------------------------------He received his BS in pharmacy from Northeastern University, PhD in pharmacology from the Ohio State University and PharmD from the University of Kentucky. He is a Board Certified Pharmacotherapy Specialist and practices in the ambulatory care and community pharmacy settings. Professor Rice is the author of Understanding Drug Action: An introduction to pharmacology (APhA, 2014) and is a fellow of the American Pharmacists Association. --------------------------He welcomes interesting medication questions and suggestions for future columns.

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