Pharmacology: Cholinoreceptor Blockers and Cholinesterase Regenerators

Question 1

What class of drugs are pirenzepine and telenzepine?

Answer 1

They are both selective M1 inhibitors

Question 2

What class of drugs are atropine, Benztropine, dicyclomine, glycopyrolate, Homatropine, cyclopentolate, tropicamide, Ipratropium, tiotropium, Oxybutynin, Scopolamine, Trospium?

Answer 2

They are non-selective antimuscarinic drug.

Question 3

What is unique about the pharmacokinetics of atropine?

Answer 3

(1) Atropine is lipid soluble (tertiary amine groups) therefore it distributes to the CNS and other organs.
(2) It is eliminated partially by the liver and partially by unchanged excretion in the urine.
(3) duration of action of 4-8 hours except in the eye (72 hours)

Question 4

What is the mechanism of action for muscarinic antagonists?

Answer 4

They act as competitive antagonists.

Question 5

What is the effect of muscarinic blocking drugs on the CNS?

Answer 5

(1) sedation
(2) anti motion sickness
(3) anti-parkinson’s
(4) amnesia
(5) delerium

Question 6

What are the effects of muscarinic blockers on the eye?

Answer 6

(1) cycloplegia
(2) mydriasis
Both block of M3

Question 7

What are the effects of muscarinic blockers on the bronchi?

Answer 7

Bronchodilation (block of M3)

Question 8

What is the effect of muscarinic blockers on the GI tract?

Answer 8

(1) relaxation
(2) slowed parastalsis
(3) reduced salivation
M1 and M3 blockade

Question 9

What is the effect of muscarinic blockers on the genitourinary tract?

Answer 9

(1) relaxation of the bladder wall (detrusor)
(2) urine retention
M3 and possibly M1 blockade

Question 10

What is the effect of muscarinic blockers on the heart?

Answer 10

(1) initial bradycardia
(2) secondary tachycardia
tachycardia from the block of M2 in the sinoatrial node

Question 11

What is the effect of muscarinic blockers on blood vessels?

Answer 11

Block of dilation but only when muscarinic agonist is present. M3 blockade

Question 12

What is the effect of muscarinic blockers on glands?

Answer 12

(1) reduction in salivation
(2) reduced lacrimation
(3) sweating
(4) decreased gastric secretions
M1 and M3 blockade

Question 13

What is the effect of muscarinic blockers on skeletal muscle?

Answer 13

None.

Question 14

What is musarinic blocker scopolamine used for used for clinically?

Answer 14

Motion sickness

Question 15

What are the muscarinic blockers commonly used to treat Parkinson’s disease?

Answer 15

Benztropine, biperiden, triheyhphenidyl.

Theses are typically second line drugs after levodopa.

Question 16

What muscarinic blockers are used to cause mydriasis?

Answer 16

Atropine
homatropine
cyclopentolate
tropicamide

Question 17

What are the muscarinic blockers tiotropium and Ipratropium used for?

Answer 17

They promote bronchodilation in asthma or COPD.

Question 18

What GI ailment can be treated with the selective M1 antagonist Prinzepine?

Answer 18

Prinzepine can be used for peptic ulcer (available in Europe)

Question 19

What are Oxybutynin and tolterodine used for?

Answer 19

To reduce urgency and bladder spasms and urgency.

Question 20

What class of drugs are Darifenacin, Fesoterodine, Solifenacin, tolterodine?

Answer 20

Muscarinic antagonists with a modest selectivity for M3 receptors.

Question 21

What are Darifenacin, Fesoterodine, Solifenacin, and tolterodine used for?

Answer 21

urinary urgency and incontinence.

Question 22

What are some predictable toxicities of muscarinic blockers?

Answer 22

(1) atropine fever (lack of sweating)(lethal in children and infants)
(2) lack of salivation and lacrimation
(3) tachycardia
(4) angle closure glaucoma (elderly)
(5) urinary retention
(6) constipation and blurred vision.

Question 23

What are some unpredicatable CNS side effects of muscarinic blockers?

Answer 23

(1) sedation
(2) amnesia
(3) delirium or hallucinations
(4) convulsions

Question 24

What are the adverse cardiovascular effects of muscarinic blockers?

Answer 24

(1) dilation of cutraneous vessels (red as a beet)

(2) Intraventricular conduction blockade.

Question 25

What are the contraindications for muscarinic blockers?

Answer 25

(1) infants (hyperthermia)
(2) patients with glaucoma
(3) Men with prostatic hyperplasia.

Question 26

What are the two principle classifications of nicotinic antagonists?

Answer 26

(1) ganglion blocking

(2) neuromuscular blocking

Question 27

What is the mechanism of action for the ganglionic blockers?

Answer 27

They are competitive antagonists of the nicotinic receptors although some may also block the ion channel itself.

Question 28

To what class of drugs do Hexamethonium, Trimethaphan, and mecamylamine belong to?

Answer 28

The are anti-nicotinic ganglion blockers.

Question 29

For what was hexamethonium used?

Answer 29

hexamethonium was used as a selective Nn blocker for the treatment of hypertension. It is rarely used anymore because it blocks both sympathetic and parasympathetic ganglionic receptors. severe side effects.

Question 30

For what is mecamylamine used for?

Answer 30

Mecamylamine is given orally and enters the CNS. it can possibly be used for smoking cessation.

Question 31

What are some adverse effects of the nicotinic blockers?

Answer 31

(1) venous pooling
(2) postrural hypotension
(3) dry mouth
(4) blurred vision
(5) constipation
(6) sexual dysfunction

Question 32

What is the principle function of the Neuromuscular blocking nicitinic antagonists?

Answer 32

They are used for muscle relaxation during surgery.

Question 33

Tubocurarine, pancuronium, atracurium, and vecuronium all belong to what class of drugs?

Answer 33

The non-depolarizing group of Nm blocking nicotinic antagonists.

Question 34

To what group of drugs does succinylcholine belong to? and what does it do?

Answer 34

Succinylcholine is a depolarizing nicotinic agonist that produces fasicularions during the induction of paralysis. Is is hydrolyzed in the plasma by butyrylcholinesterase.

Question 35

What is pralidooxime used for?

Answer 35

Pralidoxime is a cholinesterase regeneratator that has a high affinity for organophosphates. This allows the drug to pull organophosphate cholinesterase inhibitors off of cholinesterase thus restoring the enzyme to its functional form. Used for insecticide intoxication.