Anticholinergics: The diverse range of diseases a single drug can easily treat

Last Updated December 20th, 2021

What are Anticholinergics?

Anticholinergics are substances used to block neurotransmitter acetylcholine.  Let us first understand what acetylcholine is.  A neurotransmitter that aids in the communication of brain and muscles is called acetylcholine.  They block the communication between the brain and the muscle.  This prevents the muscles from contracting and can treat several diseases.  The anticholinergic agents are historically known as toxic agents.

The therapeutic effects of anticholinergic agents were utilized to treat Parkinson’s disease.  The therapeutic effects were first found by a French neurologist named Jean-Martin Charcot.  The use of anticholinergic agents declined due to the side effects and with the introduction of more suitable drugs such as levodopa for Parkinson’s disease.

These agents are presently used to treat several health conditions such as gastrointestinal symptoms, genitourinary symptoms, and respiratory symptoms.  Atropine which is an anticholinergic agent is used with anesthesia and is helpful in reducing upper respiratory secretions.  The use of atropine is very minimal as it was considered to be not safe on several patients.

Types of anticholinergics

Anticholinergic agents are broadly divided into two types namely muscarinic and nicotinic.

Muscarinic:  These receptors are present along the brain and spinal cord.  They are also located in the muscles controlled by the parasympathetic system.  These muscles include the heart, lungs, airway muscles, as well as the bladder.  Some of the examples of muscarinic anticholinergic agents include scopolamine, Ipratropium, glycopyrrolate, etc.  These agents act as antidepressants.  They perform by blocking the toxic effects of nerve agents.  They are also known to treat anxiety, bronchitis, asthma, and motion sickness.

Nicotinic:  These receptors are found at the junction where the nerves connect with skeletal muscles.  The first therapeutic use of nicotinic anticholinergics was in the use of stopping muscle contractions during surgery.  Examples of nicotinic anticholinergics include Pancuronium and mecamylamine.  Pancuronium which is mainly used as muscle relaxant can also help fight cigarette and alcohol addiction.  It is also useful as an antidepressant.  Mecamylamine was used to reduce blood pressure but is presently abandoned due to the side effects associated with it.

Uses of anticholinergics

COPD, asthma, and bronchitis treatment

Studies have revealed that muscarinic anticholinergic agents were more effective than steroids to treat respiratory symptoms such as asthma, COPD, and bronchitis.  It is believed that the effects of these agents last longer as compared to steroid medications.  In a double-blind trial tiotropium inhaler, which is a muscarinic anticholinergic agent improved the amount and rate of exhalation in 470 patients suffering from chronic obstructive pulmonary disease.  Another study has claimed that muscarinic anticholinergics with a combination of corticosteroids are more effective in treating asthma patients.

It is believed to even reduce the recurrence of asthma attacks in the future.  It is claimed that inhaling muscarinic anticholinergics can improve breathing and relieve the symptom of bronchitis.  Atrovent which is the common agent used to manage bronchitis has shown promise in improving breathing and is able to double the breathing capacity in bronchitis patients.

Potent antidepressant

The most common drug used to treat depression is with the use of TCAs (tricyclic antidepressants).  This type of drug has some anticholinergic activity.  Scopolamine is one of the examples of this drug type.  Studies have claimed that around 56-60% of people experienced improvement in their depression symptoms with the use of scopolamine.  It provides a long-lasting effect which is up to 2 weeks after treatment.  A combination of nicotinic anticholinergic mecamylamine with SSRIs is known to improve treatment-resistant depression.  Motor function and mood of a patient affected with Parkinson disease can be improved with the use of anticholinergic benztropine at small doses.

A suitable companion of anesthesia

As discussed earlier, Pancuronium is a muscle relaxant.  Studies have claimed that the use of pancuronium does not alter the heart rate as compared to another muscle relaxant.  This property of pancuronium is helpful during heart surgery.  A combination dose provided before surgery leads to less irregular heartbeats and complications.

Helps with irritable bowel syndrome

It is a long-term disorder of the digestive system.  Symptoms of irritable bowel syndrome include bloating of the stomach, abdominal pain, as well as diarrhea and constipation.  Studies have indicated that anticholinergic agents are helpful in reducing the cramping of the muscles in the stomach and intestines.  This reduces abdominal pain associated with irritable bowel syndrome.  Several clinical trials have been conducted to determine the effects of anticholinergic agents on irritable bowel syndrome and numerous positive effects have resulted.

Fights alcohol and cigarette addiction

Mecamylamine, which is an anticholinergic agent, plays an important role in fighting addiction.  A combination of mecamylamine and nicotine patches proved to be more effective in fighting cigarette addiction.  Studies have claimed that two weeks of treatment can reduce the feelings of reward from cigarettes.  It is claimed that the breath alcohol level can be reduced with the use of mecamylamine.  Using mecamylamine before consuming alcohol can reduce the sense of reward associated with alcohol consumption.

Helps in treating vertigo

Anticholinergics are able to suppress the symptoms of vertigo.  This is accomplished by reducing the sensation of motion in the ear’s sensor.  By reducing the sensation of motion, the symptoms of vertigo are reduced and gradually dissipate.  Due to difficulties in following experimental guidelines, the studies related to anti-vertigo drugs are limited.

Reduces insomnia

It is the inability to fall asleep as well as maintain it for the required period of time.  Doxepin, which is an anticholinergic agent, has shown positive effects in improving sleep patterns.  Due to the antidepressant effects of the drug, there is a calming effect on the brain.  This helps in reducing stress and enhance sleep pattern.

Limits the side effects of antipsychotics

Antipsychotics are tranquilizing medications used to reduce the effects of psychosis such as schizophrenia and bipolar disorder.  These medications are known to induce numerous side effects ranging from shakiness, restlessness, hormonal changes, constipation, etc.  It is believed that most of the side effects associated with antipsychotic medications are related to the muscles repetitively contracting.  Anticholinergic agents are proven to reduce these repetitive contractions and in turn, reduce the side effects associated with antipsychotic medications.

Reduces symptoms of BPH

Benign prostatic hyperplasia is a medical condition which leads to enlargement of the prostate and is generally associated with old age.  The main symptoms of BPH include urinary problems and erectile dysfunction.  Anticholinergic agents are helpful in reducing these symptoms associated with BPH.  The smooth muscles of the prostate and bladder are relaxed with the use of anticholinergic agents.  This improves urine flow and reduces the symptoms of BPH.

Reduces nausea associated with motion sickness

One of the main symptoms of motion sickness is associated with nausea.  The repeated motion associated with traveling leads to disturbance in the inner ear.  This leads to a feeling of nausea.  Anticholinergic agents reduce the tension in the inner ear muscles and are effective in treating nausea related to motion sickness.  Studies have indicated that anticholinergic agent such as dimenhydrinate is a more effective treatment than Vitamin B6 for treating nausea in pregnant women.

Manages Parkinson’s Disease

It is a medical condition where the nerve cells are affected causing a reduction in dopamine production.  The symptoms include stiffness associated with tremors.  Anticholinergic agents block the nerve impulses that regulate muscle movement.  These agents are generally given with a combination of anti-PD medications for more effective results.

Reduces sweating associated with anxiety

It is a psychological condition associated with feelings of anxiousness.  It is quite common to sweat excessively during anxiety attacks.  An anticholinergic agent such as glycopyrrolate directly affects the sweat glands and is helpful in reducing excessive sweating during an anxiety attack.

Side effects of anticholinergics

Anticholinergic agents consumed at appropriate doses hardly provide any side effects.  Side effects may vary depending on the medical history of a person.  Some of the potential side effects include:

  • Memory problems.
  • Dry mouth.
  • Trouble with urination.
  • Blurry vision.
  • Decreased saliva.

Side effects associated with high doses of anticholinergic agents include

Anticholinergic syndrome:  It is generally considered to be the toxicity caused by anticholinergic agents.  When the levels are exceeded beyond the maximum dose, some symptoms may arise including fast heartbeat, drowsiness, blurred vision, dry skin and mouth, hallucinations, and seizures.  This phenomenon is called anticholinergic syndrome.

Worsens brain function in elderly people:  This side effect is considered to be one of the biggest drawbacks of anticholinergic agents.  When multiple anticholinergic agents are consumed at the same time, there is a very high risk of dementia in elderly people particularly above the age of 50.

Drug interactions:  Anticholinergic agents may cause interactions with certain medications such as antipsychotic medications and diabetes medications.  Studies have claimed that when anticholinergic agents and antipsychotic medications are combined, there can be a reduction in the level of cognitive function.  The interaction is higher with the addition of higher doses of anticholinergic agents.  People suffering from dementia consume anti-dementia medication and generally also combine it with anticholinergic agents to prevent overdosing.

Due to the interaction of these medications, the person ends up being at higher risk of worsening dementia symptoms.  Similarly, anticholinergic agents can interact with diabetes medications used to reduce blood sugar levels such as metformin.  Due to the interaction of these medications, the blood sugar levels end up becoming higher whereas it is supposed to reduce blood sugar levels.

May cause heat stroke:  As discussed earlier, anticholinergic agents have the ability to directly affect the sweat glands and reduce the amount of sweat produced by the body.  Sweating is important to regulate the temperature of the body.  When there is a decreased level of sweat produced, you may end up getting a heat stroke due to the increase in body temperature.

Final thoughts

Anticholinergic agents are helpful in treating several medical conditions, but there is a big problem associated with it.  They are not suitable for patients who are old.  It is claimed that they may induce dementia in older people.  Since anticholinergic agents are prescribed medications, it is important to speak to your doctor, if you are really eligible to take this medication.  Your doctor would weigh upon several factors before prescribing you these medications including age, daily medications, as well as a health condition.  All these factors play an important role in determining if you are eligible to take these medications.  If you are prescribed with these medications, it is important to follow the directions to avoid the various side effects associated with these medications.



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