Antimuscarinic Drugs (Non-Bladder)

Although antimuscarinic drugs are commonly referred to as anticholinergic drugs, the drugs work primarily at muscarinic receptors, and therefore, do not interact at the neuromuscular junctions or in autonomic ganglia.

Atropine is a commonly tested drug from this class. Atropine is used in the treatment of severe bradycardia and as an antidote along with pralidoxime (2-PAM) in the treatment of cholinergic toxicity. Atropine and dicyclomine can be used to decrease bowel spasms. Dicyclomine is used in combination with vitamin B6 to treat pregnancy induced nausea. Atropine and cyclopentolate also induce mydriasis and cycloplegia.

Benztropine is useful in the treatment of extrapyramidal side effects and is sometimes used in the treatment of Parkinson's disease.

Ipratropium and tiotropium are used for maintenance therapy for COPD. Ipratropium is also indicated for treatment of bronchospasm in asthma.

Scopolamine is used in the treatment of motion sickness and is available in a transdermal patch formulation.

Use the phrase "Blind as a bat (mydriasis), Red as a beet (erythema), Dry as a bone (dry mouth/skin/eyes), Hot as hades (hyperthermia), and Mad as a hatter" to help remember the adverse effect of these drugs.

Class Drugs

• Atropine

• Benztropine

• Cyclopentolate

• Dicyclomine

• Ipratropium

• Scopolamine

• Tiotropium

• Trihexyphenidyl

Class Mechanism of Action

• Blocks muscarinic receptors

• Blocks sympathetic cholinergic receptors

Class Adverse Effects

• Blind as a bat (mydriasis)

• Red as a beet (erythema)

• Dry as a bone (dry mouth/skin/eyes)

• Hot as hades (hyperthermia)

• Mad as a hatter (delirium)

• Urinary retention

• Constipation

Drug Table

Drug Name	Application	Comments	Image
Atropine	Ophthalmologic: ; Causes mydriasis, cycloplegia, and decreases responsiveness to light.; Used in Iritis to limit pain from pupillary changes. Used to dilate eyes for examination.; Gastrointestinal: Used as an antispasmodic to reduce GI motility; Cardiovascular: Increases HR in high doses by blocking M2 receptors at SA node. (At low doses can cause bradycardia by blocking M1 receptors at inhibitory neurons); Glands: Decreases secretions of salivary and sweat glands; Toxicology: Antidote for cholinergic toxicity (insecticides, nerve gas, and cholinergic drugs)	Adverse Effects; Ophthalmologic: Can induce acute angle closure glaucoma; Causes effects of class toxicity and can be quite severe in overdose: delirium, hallucinations, which can eventually lead to circulatory collapse. Antidote: Physostigmine	"Pine Tree Air-Freshener"
Benztropine	Parkinson's disease; Treatment of extrapyramidal side effects of antipsychotics		"Mercedes-Benz Logo"
Cyclopentolate	Ophthalmologic: Induces cycloplegia and mydriasis		"Bicycle", "Pen", and "Latte"
Dicyclomine	Antispasmodic for GI tract; Nausea and vomiting in pregnancy: used in combination with pyridoxine (B6)		"Dice" and "Bicycle"
Scopolamine	Motion sickness		"Scope Bottle"
Ipratropium	Acute bronchospasm in asthma, short acting; Maintenance therapy for COPD	Inhalation	"I", "Rope", "Opium"
Tiotropium	Maintenance therapy for COPD	Inhalation	"Uncle", "Rope", "Opium"
Trihexyphenidyl	Adjunct for treatment of Parkinson's disease; Treatment of extrapyramidal side effects of antipsychotics		"Tricycle", "Hexagon", and "Fence"