Muscarinic antagonists: Uses, most common brand names, and safety information

Medically reviewed by  Jamie Winn, PharmD

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Muscarinic antagonists originate from a perennial plant in the nightshade family called Solanaceae. It has been used for hundreds of years in many cultures around the world. Until the beginning of the 20th century, muscarinic antagonists were widely used to treat psychiatric disorders. A muscarinic antagonist, atropine, became the standard bronchodilator for various respiratory illnesses in the early 1900s, long before beta-agonists. This class of medications works by inhibiting the cholinergic activity of the parasympathetic nervous system. Muscarinic antagonists are also used to treat a wide range of conditions such as chronic obstructive pulmonary disease (COPD), gastrointestinal (GI) disorders, and Parkinson’s disease. They can be used as monotherapy or as combination therapy with medications such as long-acting beta-agonists (LABA) and inhaled corticosteroids (ICS)

The list below includes muscarinic antagonists approved by the U.S. Food and Drug Administration (FDA) and their pricing:

List of muscarinic antagonists

What are muscarinic antagonists?

Muscarinic antagonists are a class of medications that are also known as anticholinergics. There are over 600 medications including antipsychotics, antihistamines, and tricyclic antidepressants, which have some antimuscarinic properties. In almost all of these medications, the anticholinergic activity is the cause of adverse effects and has no therapeutic value.

Muscarinic antagonists are typically categorized as long-acting muscarinic antagonists (LAMAs) or short-acting muscarinic antagonists (SAMAs). They have effects on your circulation, respiration, vision, and alertness. They are effective for treating respiratory diseases such as asthma, Parkinson’s disease, overactive bladder, and allergies.

How do muscarinic antagonists work?

The parasympathetic nervous system releases acetylcholine (ACh), which binds to and activates muscarinic and nicotinic receptors. Muscarinic receptor antagonists work as competitive inhibitors on the various muscarinic receptor subtypes in the parasympathetic nervous system. These medications can also affect neurotransmitters in the central nervous system (CNS). It is thought that their therapeutic effect comes from the inhibition of M3 receptors on the smooth muscle of your airway, GI tract, urinary tract, heart, and blood vessels. By binding to these M3 receptors, these anticholinergic agents:

• reduce bladder contractions, increase the amount of urine your bladder can hold, and reduce how often you urinate. This should be used with caution with patients with prostate problems or who are prone to urinary retention.
• reduce peristalsis which can help relieve cramps or spasms in your stomach, intestines, and bladder.
• reduce salivary, gastric, and bronchial secretions.
• relax smooth muscles in the airway to increase bronchodilation.

What conditions are muscarinic antagonists used to treat?

Muscarinic antagonists are a class of medications used in the treatment of:

• Chronic obstructive pulmonary disease (COPD)
• Overactive bladder
• Asthma exacerbations
• Irritable bowel syndrome (IBS)
• Parkinson’s disease
• Peptic ulcers
• Nausea and vomiting
• Allergies
• Motion sickness
• Excessive drooling or sweating
• Bradycardia (low heart rate)
• Used to dilate pupils (mydriasis) for certain procedures

Are muscarinic antagonists safe?

The use of muscarinic antagonists is relatively safe and effective when taken as prescribed. There are certain conditions that can worsen with the use of muscarinic antagonists, including:

• Dementia
• Glaucoma
• Hyperthyroidism
• Rapid heartbeat (tachycardia)
• Enlarged prostate or bladder problems
• Depression
• Autonomic neuropathy
• Myasthenia gravis
• Tardive dyskinesia
• History of milk protein allergy if using a dry powder inhaler

What are the common side effects of muscarinic antagonists?

The adverse effects you experience from muscarinic antagonists will depend on several factors including the medication and dose. The most common adverse effects in clinical trials when compared to placebo include:

• Dry mouth, eyes, or skin
• Memory problems
• Confusion
• Constipation
• Nausea
• Blurred vision
• Increased heart rate
• Irregular heartbeat (arrhythmia)
• Drowsiness
• Weakness
• Difficulty urinating
• Dilated pupils
• Decreased sweating
• Flushing
• Headache
• Narrow-angle glaucoma

This is not a complete list of adverse events and we encourage you to consult with your healthcare provider or mental health professional for medical advice about any possible side effects.

Which drugs are muscarinic receptor antagonists?

Some of the most common muscarinic receptor antagonists include atropine, hyoscyamine, ipratropium bromide, scopolamine, glycopyrrolate, and tiotropium.

What are the signs of muscarinic antagonist overdose?

You should call your doctor or go to the nearest emergency department if you have symptoms of overdose, including urinary retention, irregular heartbeat, abnormally high body temperature, dizziness, confusion, difficulty breathing, or tremors.

How much do muscarinic antagonists cost?

Muscarinic antagonists are very expensive with an average cost of up to $10,000 per year.

You can purchase muscarinic antagonists for $49 per month from NiceRx if eligible for assistance. Prices at the pharmacy vary by location, strength, and quantity, as well as your insurance status.

Related resources for muscarinic antagonists

• https://www.ncbi.nlm.nih.gov/books/NBK555893/
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2692120/
• https://www.medicalnewstoday.com/articles/323514#what-are-they
• https://www.sciencedirect.com/topics/neuroscience/muscarinic-antagonist
• https://www.ncbi.nlm.nih.gov/books/NBK557541/
• https://www.mayoclinic.org/drugs-supplements/anticholinergics-and-antispasmodics-oral-route-parenteral-route-rectal-route-transdermal-route/description/drg-20070312
• https://doi.org/10.1016/j.anai.2021.12.020