8 Cholinergics II

Question 1

What are the two main classes of anticholinergics?

Answer 1

anti-muscarinics/parasympatholytics and anti-nicotinics

Question 2

What is the main therapeutically significant difference between tertiary amines and quaternary ammoniums, and how does this dictate when and for what purpose they are used?

Answer 2

Tertiary amines are uncharged and exhibit good absorption across gut and conjuctival membranes, so they are often used for ocular or CNS effects.
Quaternary ammoniums are positively charged and exhibit poor absorption across membranes due to poor lipid solubility, and so are often used to decrease CNS effects and increase potency at muscarinic receptors

Question 3

T or F: Antimuscarinic drugs are used to induce mydriasis without cycloplegia

Answer 3

F; antimuscarinic drugs are used to induce both mydriasis and cycloplegia together

Question 4

Atropine, homatropine, and tropicamide are all antimuscarinic drugs used in ophthalmology. Which is the longest acting? The shortest acting?

Answer 4

Atropine is long-acting
Homatropine is intermediate
Tropicamide is short-acting

Question 5

What effect do drugs like atropine have on the heart?

Answer 5

Muscarinic antagonists block vagal slowing of the heart and produce tachycardia

Question 6

What effects do antimuscarinics have on the airway?

Answer 6

They reduce secretions and elicit bronchodilation

Question 7

What effect do muscarinic antagonists have on the GI tract?

Answer 7

Antimuscarinics decrease smooth muscle motility and secretions in the GI tract

Question 8

What effect do antimuscarinics have on salivary glands?

Answer 8

They reduce salivation, and may be used to treat excess salivation due to heavy metal poisoning or parkinson’s

Question 9

What effect do antimuscarinics have on sweat glands?

Answer 9

They reduce the activity of thermoregulatory sweat glands

Question 10

What is atropine fever, and why is it caused by antimuscarinics?

Answer 10

Atropine fever is an increased body temperature due to an impaired ability to sweat. Antimuscarinics cause this condition by inhibiting thermoregulatory sweat glands.

Question 11

What effects do antimuscarinics have on the genitourinary system?

Answer 11

Decrease smooth muscle contraction of the bladder wall and decrease urination

Question 12

T or F: Antimuscarinics are used for their CNS effects to treat parkinsons and motion sickness.

Answer 12

T

Question 13

Ipratropium is a quaternary derivative of which antimuscarinic? What are some of its uses?

Answer 13

It is a quaternary derivative of Atropine, used for bronchodilation in patients with airway problems

Question 14

Which drug is a quaternary derivative of scopolamine? For what type of illnesses is it used?

Answer 14

Methscopolamine; it lacks the CNS effects of scopolamine, and so is used primarily for GI diseases

Question 15

Is atropine a tertiary amine or quaternary ammonium? Is it selective for either muscarinic or nicotinic receptors?

Answer 15

A tertiary amine; it is highly selective for muscarinic receptors with low potency at nicotinic.

Question 16

What are some of the therapeutic uses for atropine? Which areas of the body are most sensitive to atropine?

Answer 16

Mydriasis and cycloplegia, relieves urinary incontinence, useful adjunct therapy for parkinsons, overcome poisoning by O-P or muscarine mushrooms; salivary, bronchial, and sweat glands are most sensitive to atropine

Question 17

Is scopolamine a tertiary amine or quaternary ammonium? Is it selective for either muscarinic or nicotinic receptors?

Answer 17

Tertiary amine that has strong antimuscarinic effects

Question 18

What are the main therapeutic uses for Scopolamine?

Answer 18

Elicits CNS depression (drowsiness, amnesia, etc), and was historically used as an adjunct for pre-anesthetic medication, used also to treat motion sickness.

Question 19

Is methscopolamine a tertiary amine or quaternary ammonium? What are the main therapeutic uses?

Answer 19

A quaternary ammonium with no CNS effects; It is used primarily for GI diseases, but also has significant effects in inhibiting secretions of respiratory tract

Question 20

Is homatropine a tertiary amine or quaternary ammonium? What are the main therapeutic uses, and what is its duration of action?

Answer 20

Tertiary amine derivative of atropine used as a topical mydriatic and cycoplegic agent. Duration of action is 2-4 hours

Question 21

Is trihexyphenidyl a tertiary amine or quaternary ammonium? What are the main therapeutic uses?

Answer 21

A tertiary amine antimuscarinic used as an adjunct therapy to decrease unwanted movement and excess salivation in parkinsons patients

Question 22

Is tropicamide a tertiary amine or quaternary ammonium? What are the main therapeutic uses and duration of action?

Answer 22

A tertiary amine antimuscarinic used as a topical mydriatic and cycoplegic agent. Duration of action is 0.5-1.5 hours