Antimuscarinics

Question 1

what does atropine block

Answer 1

muscarinic

Question 2

dose related effects of atropine: .5mg

Answer 2

some dryness of mouth, inhibition of sweating

Question 3

dose related effects of atropine: 2mg

Answer 3

marked dryness of mouth, rapid HR, dilated pupils

Question 4

dose related effects of atropine: 10mg

Answer 4

above symptoms more marked, ataxia, restlessness, excitement, hallucinations, delerium

Question 5

uses of atropine type-drugs

Answer 5

• Mydriatics to dilate pupil
• eye-exam, inspection
• torn iris, iritis
• herpes infection to break synechiae
• onset duration cyclopentolate
• tropicamide

Question 6

Antimuscarinics to decrease respiratory secretions

Answer 6

• preanesthetic mediation
• decrease accumulation of fluid in lungs
• block excess vagal activity in anesthesia and surgery

Question 7

antimuscarinics to decrease GI activity

Answer 7

IBS most common side effect
“antispasmodic” effect
-irritable bowel syndrome “IBS”
-common problem especially in women (3X more common)
-spastic constipation or diarrhea
-Treat: may contain small amounts of artopine or scopolamine and a mild sedative

Question 8

acetylocholine relaxes

Answer 8

blood vessels

Question 9

antimuscarinics in urinary incontinence (enuresis)

Answer 9

• 30% of 4 year olds have bed wetting
• increasingly common in elderly and also occurs in children
• drugs are competitive blockers of muscarinic receptors
• drugs effective but dryness of mouth and eyes limits tolerability and compliance

Question 10

Atropine Analogs for Enuresis

Answer 10

Oxybutinin
Tolterodine
Solifenacin

Question 11

Oxybutinin

Answer 11

• 7 times stronger than atropine as antispasmodic but only 20% of dry mouth problem
• skin patch even more tolerable
• no effects on GI tract

Question 12

Tolterodine

Answer 12

more tolerable than oxybutinin

Question 13

Solifenacin

Answer 13

reduced xerostomia, constipation

• duration 24 hour
• has specificity for M3 receptors (bladder), not much effect on M2, so no effects really on the heart

Question 14

Antimuscarinics for bronchoconstriction

Answer 14

• decreases hyperactive vagal reflex
• ipratropium inhaler-> quaternary
• tiotropium-> lasts 24 hours
• both quaternary, not absorbed
• no decrease ciliary activity; little drying

Question 15

antimuscarinics for bradycardia after MI

Answer 15

• sinus bradycardia can occur during acute infection

- use cautiously to restore cardiac output

Question 16

receptor specificity of antimuscarinics: Atropine

Answer 16

• relatively non-specific

- good for M2 and M3, but less effective on M1

Question 17

receptor specificity of antimuscarinics: Pirenzepine

Answer 17

-some specificity for M1

Question 18

CNS effect of teritary amine antimuscarinics

Answer 18

atropine
scopolamine 
mydriatics
drugs for enuresis
antidote, physostigmine

Question 19

effects of CNS teritary amine antimuscarinic

Answer 19

restlessness, ataxia, hallucinations, psychosis in high doses
-children and elderly especially susceptable

Question 20

synthetic antimuscarinics

Answer 20

Some are quaternary ammonium: methscopolamine
-no CNS side effects
Some have direct effect on smooth muscle
-Dicyclomine

Question 21

what are the precautions for using antimuscarinics

Answer 21

1. Bad heart, vagal activity less in infants and old age
2. intestinal atony (constipation, make it worse)
3. eye infection
4. blurred vision
5. glaucoma
6. prostatic hypertrophy
7. block sweating

“dry as a bone, blind as a bat, red as a beet, mad as a hatter”

Question 22

best selling antimuscarnic drug on the market

Answer 22

Solifenacin

Question 23

antimuscarinic for bradycardia after an MI?

Answer 23

atropine

Question 24

2mg of atropine does

Answer 24

in a young man increases heart rate 35-40 beats/min

-must be careful in someone who has a bad heart