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Everything You Need To Know About Anticholinergic Drugs

Anticholinergic refers to a broad class of drugs that treat different conditions. These conditions include muscle spasms, breathing difficulties, overactive bladder, and diarrhea. Ideally, anticholinergic drugs treat these conditions by reducing muscle activity.

In this article, you will find out more about anticholinergic drugs, their uses, side effects, prescription, and contraindications.

What Is An Anticholinergic?

Anticholinergics treat a wide range of medical conditions. These medications work by blocking the action of acetylcholine, a neurotransmitter. Acetylcholine transfers signals between cells responsible for specific bodily functions.

Acetylcholine causes involuntary muscle movement in the urinary tract, digestive tract, lungs, and other areas in the body. Anticholinergics block acetylcholine from causing these involuntary muscle movements. So, these medications can affect various bodily functions such as salivation, digestion, and urination. That explains why they can treat a wide range of medical conditions.

How Does Anticholinergics Work?

By blocking acetylcholine from binding with receptors on specific nerve cells, anticholinergics inhibit parasympathetic nerve impulses. These are the impulses responsible for involuntary muscle movement in the:

  • Digestive system
  • Urinary tract
  • Lungs
  • And other body organs and systems

These nerve impulses are responsible for bodily functions such as:

  • Urination
  • Digestion
  • Salivation
  • Secretion of mucus

Therefore, anticholinergics can have effects such as:

  • Retaining urine
  • Reducing mucus secretion
  • Dry mouth

Uses of Anticholinergics

Anticholinergics treat the following medical conditions:

  • Motion sickness
  • Chronic obstructive pulmonary disease
  • Dizziness
  • Asthma
  • Abnormal involuntary muscle movement in Parkinson’s disease patients
  • Diarrhea
  • Poisoning caused by certain insecticides, mushrooms, and plants
  • Overactive bladder
  • Nausea
  • Muscle spasms

Classification of Anticholinergic Drugs

There are three classifications of anticholinergic medications. The classification is based on the receptors the drugs affect.

  1. Antimuscarinic agents

These drugs act on the muscarinic acetylcholine receptors. Most anticholinergic drugs, including atropine, are antimuscarinics.

Antimuscarinics bind competitively, preventing acetylcholine from binding with cell receptors. They produce effects opposite to the effects of acetylcholine. They produce effects such as anti-motion sickness, sedation, amnesia, delirium, and anti-Parkinson’s effects.

  1. Antinicotinic agents

Antinicotinic act on the nicotinic acetylcholine receptors. These drugs are further categorized into neuromuscular blocking agents and ganglionic blockers.

Neuromuscular blocking agents competitively bind with the nicotinic acetylcholine receptors. These blockers are further categorized into two – non-depolarizing and depolarizing agents. The latter stimulates muscle cells while non-polarizing blocking agents inhibit muscular contraction by preventing the polarization of muscle cells.

Neuromuscular blocking agents are mostly used as muscular relaxants. Also, they provide fast recovery from anesthesia, facilitate the endotracheal intubation process, and reduce postoperative respiratory depression.

Ganglionic blocking agents act on the nicotinic receptors in the parasympathetic and sympathetic nervous system.

  1. Cholinesterase regenerators

Cholinesterase regenerators, such as pralidoxime, are used in the treatment of organophosphate poisoning. Organophosphate chemicals such as Malathion and parathion inhibit cholinesterase. Therefore, the administration of cholinesterase regenerators helps fight the effects of organophosphate compounds.

List of Anticholinergics

Different anticholinergics are effective against various symptoms and conditions. Also, it is essential to note that these medications need a doctor’s prescription.

The common anticholinergic drugs include:

  • atropine (Atropine)
  • benztropine mesylate (Cogentin)
  • belladonna alkaloids
  • cyclopentolate (Cyclogyl)
  • clidinium
  • dicylomine
  • darifenacin (Enablex)
  • flavoxate
  • fesoterodine
  • glycopyrrolate
  • hyoscyamine
  • homatropine hydrobromide
  • ipratropium
  • methscopolamine
  • oxybutynin
  • orphenadrine
  • propantheline
  • scopolamine
  • solifenacin
  • trihexyphenidyl
  • tiotropium
  • trospium
  • tolterodine

Side Effects of Anticholinergics

The proper dosage of anticholinergics is usually safe. However, some people do experience side effects.

These side effects vary from an individual to the other and are influenced by a person’s medical history, the dosage, and the type of anticholinergic taken.

Some of the side affects you could experience include:

  • Dry mouth
  • Trouble urinating
  • Decreased sweating
  • Constipation
  • Blurry vision
  • Drowsiness
  • Confusion
  • Delirium
  • Hallucination
  • Memory problems

Who Cannot Use Anticholinergics?

Even though anticholinergics treat a variety of conditions, they are not for everyone. For instance, they are discouraged for use in older adults.

People with the conditions listed below should avoid anticholinergics:

  • Hyperthyroidism
  • Enlarged prostate
  • Severe constipation
  • Hypertension
  • Heart failure
  • Hiatal hernia
  • Down syndrome
  • Glaucoma
  • Tachycardia (increased heart rate)
  • Urinary tract blockage
  • Myasthenia gravis

The Risk of Anticholinergics in the Elderly

Elderly people should avoid anticholinergics. Individuals over the age of 65 have a diminishing number of neurons. So, blocking acetylcholine only adds insult to injury.

Moreover, medications stay longer in the system of an elderly person. The aging liver and kidney do not work as fast. So, chemicals in drugs remain in the body for longer than usual. In this case, the result is a build-up of anticholinergics, which can have unwanted side effects such as dry mouth and urine retention.

Furthermore, reduced sweating increases the risk of dehydration. Other dangers of anticholinergics in the elderly include:

  • Stroke
  • Constipation
  • Dizziness
  • Drowsiness
  • Blurred vision
  • Hallucinations
  • Delirium

These side effects can be fatal in an elderly person.

The Risk of Heatstroke or Heat Exhaustion

Anticholinergics decrease how much you sweat. Yet, sweating is the body’s natural response to heat. So, the lack of sweating increases body temperature.

So, when on these medications, be cautious not to overheat when in the hot weather, taking a hot bath or exercising.

Decreased sweating can result in both heatstroke and heat exhaustion. Both of these conditions are as severe as to cause death.

Signs of Anticholinergics Overdose

An overdose of anticholinergics can cause symptoms ranging from fever to death. The signs of overdose include:

  • Severe dizziness
  • Severe drowsiness
  • Hallucinations
  • Confusion
  • Flushing of the skin
  • Increased heartbeat
  • Clumsy and slurry speech
  • Breathing difficulty

These are the same things that might happen if you accompany anticholinergics with alcohol.

Anticholinergics and Dementia

People with cognitive impairment, delirium, or dementia should not use anticholinergics. According to research published in the Journal of American Medicine Association, the long-term use of anticholinergics increases the risk of dementia.

Some of anticholinergics commonly used by elderly people include:

  • Overactive bladder antimuscarinics
  • Tricyclic antidepressants
  • First-generation antihistamines

The use of such medication for more than three years increases the risk of dementia by 54%. Unfortunately, the risk of dementia is still high even after you stop using anticholinergics.

Since dementia mostly affects the elderly, the use of these medications should be avoided in seniors unless clearly needed, and there are no other appropriate alternatives.

Anticholinergics and Pregnancy

Unfortunately, there isn’t enough research on the effects of anticholinergics on pregnant women. So, if you are pregnant or plan to be pregnant, consult your doctor before starting a treatment regimen that includes anticholinergics.

The Use of Anticholinergics by Lactating Mothers

Chemical compounds from medication can get to human milk and cause unwanted effects in the breastfeeding baby. For that reason, lactating mothers should be cautious about the medications they are taking.

Most medications come with information about their dosage for breastfeeding mothers. You could also ask a doctor to recommend medication that cannot harm your baby.

Are There Other Drugs That Can Interact With Anticholinergics?

The use of certain drugs while taking anticholinergics can be potentially dangerous due to the cumulative anticholinergic side effects. The following are medications with anticholinergic properties that should be avoided while taking anticholinergics:

  • Antidepressants
  • Antispasmodics
  • Antipsychotics
  • Histamine 1-receptor blockers (H1RA)
  • Motion sickness medication
  • Overactive bladder medication
  • Anti-diarrhea
  • Parkinson’s disease medication
  • Certain types of antiemetics

With medication, it is always advisable to exercise caution. So, always consult a doctor about potential drug interactions.

Dosage

The dosage of anticholinergics is different for different patients. Therefore, you should follow your physician’s directions.

Of course, the dosage depends on the strength of the medication, the time allowed between doses, the duration of the dosage, and the medical problem you have. Due to the adverse nature of some of the side effects of anticholinergics, avoid changing your dosage without the direction of a qualified doctor.

Summary

Anticholinergics affect involuntary muscle movement and several other bodily functions. So, they can be used to treat many different medical conditions. However, there are safety concerns and medical risks you need to consider before taking these medications.