CHOLINOCEPTOR-BLOCKING DRUGS

Question 1

MUSCARINIC ANTAGONISTS
 Selective
 Only a few receptor-selective
--- antagonists have reached clinical trial
 Pirenzipine

Answer 1

M1

Question 2

MUSCARINIC ANTAGONISTS
A. CLASSIFICATION AND PHARMACOKINETICS
Subdivided into

 Most of the drugs in the market

Answer 2

2. Nonselective

Question 3

Cholinoreceptor antagotists are divided into two:

• Muscarinic, blocks parasympathetic autonomic discharge. Atropine is the prototype of these drugs.
• Nicotinic, competitively block the actions of acetylcholine at nicotinic receptors of both parasympathetic and sympathetic ganglia.

Answer 3

MUSCARINIC

NICOTINIC

Question 4

Cholinoreceptor antagotists are divided into two:

blocks parasympathetic autonomic discharge. Atropine is the prototype of these drugs.

Answer 4

Muscarinic

Question 5

Cholinoreceptor antagotists are divided into two:

competitively block the actions of acetylcholine at nicotinic receptors of both parasympathetic and sympathetic ganglia.

Answer 5

Nicotinic

Question 6

 Prototype nonselective muscarinic
blocker
 Derivative of a deadly night shade
Atropa belladona and other plants

Answer 6

ATROPINE

Question 7

 Tertiary amine
 Relatively lipid soluble
 Crosses membrane barriers
 Well distributed in the CNS and other
organs

Answer 7

ATROPINE

Question 8

 Eliminated partially by metabolism in
the liver
 Partially by renal excretion
 Elimination half-life is 2 hours

Answer 8

ATROPINE

Question 9

 Duration of action of normal doses is
4-8 hours in all organs
 For the eye, it last for 72 hours
 Salivary or bronchial glands are
sensitive to the effect of atropine

Answer 9

ATROPINE

Question 10

organ affected by muscarinic antagonists

Sedation, hallucination, drowsiness, antimotion sickness action, antiparkinson action, amnesia

Answer 10

CNS

Question 11

organ affected by muscarinic antagonists

Mydriasis, cyclopegia, lacrimal glands become dry and sandy

Answer 11

eye

Question 12

organ affected by muscarinic antagonists

Initial bradycardia at low doses then tachycardia

Answer 12

heart

Question 13

organ affected by muscarinic antagonists

Bronchodilation, decrease in bronchial secretions

Answer 13

Respiratory

Question 14

organ affected by muscarinic antagonists
Relaxation, decrease motility, antidiarrheal, prolongs gastric
emptying time

Answer 14

GIT

Question 15

organ affected by muscarinic antagonists

Relaxation of the bladder wall, urinary retention

Answer 15

gut

Question 16

organ affected by muscarinic antagonists

Decrease secretion, salivation, lacrimation, sweating

Answer 16

gland

Question 17

organ affected by muscarinic antagonists

None

Answer 17

skeletal muscle

Question 18

EFFECTS OF INCREASING DOSE OF
ATROPINE
(7)

Answer 18

 Decrease bronchial and salivary
secretions
 Decrease sweating
 Mydriasis
 Tachycardia
 Urinary hesitancy
 Decrease intestinal motility
 Decrease gastric secretion

Question 19

MUSCARINIC ANTAGONISTS
D. CLINICAL USES
1. CNS

Answer 19

 Parkinson’s disease
 Decrease dopamine and cholinergic
transmission
 Benztrypine, biperiden,
trihexyphenidyl

Question 20

MUSCARINIC ANTAGONISTS
D. CLINICAL USES
2. EYE

Answer 20

 Used to dilate the pupil

 Paralyze accommodation

Question 21

D. CLINICAL USES

1. CNS

Answer 21

 Widely distributed
 Excreted rapidly
 Standard therapy for motion sickness
 Dicyclomine

Question 22

 Used to reduce airway secretions

during general anesthesia

Answer 22

IV atropine

Question 23

 Quaternary antimuscarinic agent
 Used by inhalation
 Promote bronchodilation
 Asthma and COPD

Answer 23

Ipratropium

Question 24

 Used for peptic ulcer

Answer 24

M1-selective inhibitor pirenzipine

Question 25

 Used to reduce acid secretion  Not as effective as the H 2 antagonists

Answer 25

Atropine

Question 26

MUSCARINIC ANTAGONISTS D. CLINICAL USES 5. GUT

Answer 26

 Used to reduce urgency in mild cystitis  Used to reduce bladder spasm following urologic surgery Treatment of enuresis

Question 27

MUSCARINIC ANTAGONISTS D. CLINICAL USES 6. CHOLINERGIC POISONING

Answer 27

 Antidote for organophosphate insecticide poisoning

Question 28

 Blockade of thermoregulatory sweating  Can result to hyperthermia

Answer 28

“Atropine fever”

Question 29

 Dilation of the cutaneous vessels | of the arm, head, neck and trunk

Answer 29

“Atropine flush”

Question 30

NICOTINIC ANTAGONISTS A. CLASSIFICATION Subdivided into  Act like competitive pharmacologic antagonists  First successful agents for the treatment of hypertension

Answer 30

1. GANGLION-BLOCKING DRUGS

Question 31

1. GANGLION-BLOCKING DRUGS

Answer 31

 Tetraethylammonium, hexamethonium  Mecamylamine (increase oral absorption)  Trimethaphan (hypertensive emergencies)

Question 32

NICOTINIC ANTAGONISTS A. CLASSIFICATION  Adverse effects in hypertension are so severe  Both sympathetic and parasympathetic are blocked

Answer 32

1. GANGLION-BLOCKING DRUGS

Question 33

1. GANGLION-BLOCKING DRUGS |  Adverse effects

Answer 33

Dry mouth  Blurred vision  Severe sexual dysfunction

Question 34

NICOTINIC ANTAGONISTS A. CLASSIFICATION  Important for producing complete muscle skeletal relaxation in surgery  Classified into two

Answer 34

2. NEUROMUSCULAR-BLOCKING DRUGS

Question 35

NEUROMUSCULAR-BLOCKING DRUGS  Tubocurarine is the prototype  Competitive block at the end plate nicotinic receptor

Answer 35

a. NONDEPOLARIZING GROUP

Question 36

NEUROMUSCULAR-BLOCKING DRUGS  Causes flaccid paralysis  Last for 30-60 minutes  Pancuronium, atracurium, vecuronium

Answer 36

a. NONDEPOLARIZING GROUP

Question 37

NEUROMUSCULAR-BLOCKING DRUGS  Nicotinic agonists not antagonists that cause flaccid paralysis  Succinylcholine is the only member

Answer 37

b. DEPOLARIZING GROUP

Question 38

effect of nicotinic antagonists on the CNS

Answer 38

Sedation, tremor

Question 39

effect of nicotinic antagonists on the EYE

Answer 39

Mydriasis and cycloplegia

Question 40

effect of nicotinic antagonists on the GIT

Answer 40

Marked reduced motility, constipation

Question 41

effect of nicotinic antagonists on the GUT

Answer 41

Reduced contractility of the bladder, urinary | hesitancy, impairment of erection and ejaculation

Question 42

effect of nicotinic antagonists on the HEART

Answer 42

Vasodilator, antihypertensive, tachycardia

Question 43

effect of nicotinic antagonists on the BLOOD VESSELS

Answer 43

Reduction in arteriolar and venous tone, BP decrease, | orthostatic hypotension

Question 44

effect of nicotinic antagonists on the GLANDS

Answer 44

Reduction in salivation, lacrimation, sweating and | gastric secretion