CHOLINOCEPTOR-BLOCKING DRUGS Flashcards

1
Q
MUSCARINIC ANTAGONISTS
 Selective
 Only a few receptor-selective
--- antagonists have reached clinical trial
 Pirenzipine
A

M1

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2
Q

MUSCARINIC ANTAGONISTS
A. CLASSIFICATION AND PHARMACOKINETICS
Subdivided into

 Most of the drugs in the market

A
  1. Nonselective
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3
Q

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.
A

MUSCARINIC

NICOTINIC

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4
Q

Cholinoreceptor antagotists are divided into two:

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

A

Muscarinic

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5
Q

Cholinoreceptor antagotists are divided into two:

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

A

Nicotinic

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6
Q

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

A

ATROPINE

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7
Q
 Tertiary amine
 Relatively lipid soluble
 Crosses membrane barriers
 Well distributed in the CNS and other
organs
A

ATROPINE

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8
Q

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

A

ATROPINE

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9
Q
 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
A

ATROPINE

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10
Q

organ affected by muscarinic antagonists

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

A

CNS

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11
Q

organ affected by muscarinic antagonists

Mydriasis, cyclopegia, lacrimal glands become dry and sandy

A

eye

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12
Q

organ affected by muscarinic antagonists

Initial bradycardia at low doses then tachycardia

A

heart

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13
Q

organ affected by muscarinic antagonists

Bronchodilation, decrease in bronchial secretions

A

Respiratory

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14
Q

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

A

GIT

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15
Q

organ affected by muscarinic antagonists

Relaxation of the bladder wall, urinary retention

A

gut

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16
Q

organ affected by muscarinic antagonists

Decrease secretion, salivation, lacrimation, sweating

A

gland

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17
Q

organ affected by muscarinic antagonists

None

A

skeletal muscle

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18
Q

EFFECTS OF INCREASING DOSE OF
ATROPINE
(7)

A
 Decrease bronchial and salivary
secretions
 Decrease sweating
 Mydriasis
 Tachycardia
 Urinary hesitancy
 Decrease intestinal motility
 Decrease gastric secretion
19
Q

MUSCARINIC ANTAGONISTS
D. CLINICAL USES
1. CNS

A
 Parkinson’s disease
 Decrease dopamine and cholinergic
transmission
 Benztrypine, biperiden,
trihexyphenidyl
20
Q

MUSCARINIC ANTAGONISTS
D. CLINICAL USES
2. EYE

A

 Used to dilate the pupil

 Paralyze accommodation

21
Q

D. CLINICAL USES

1. CNS

A

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

22
Q

 Used to reduce airway secretions

during general anesthesia

A

IV atropine

23
Q

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

A

Ipratropium

24
Q

 Used for peptic ulcer

A

M1-selective inhibitor pirenzipine

25
Q

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

A

Atropine

26
Q

MUSCARINIC ANTAGONISTS
D. CLINICAL USES
5. GUT

A

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

27
Q

MUSCARINIC ANTAGONISTS
D. CLINICAL USES
6. CHOLINERGIC POISONING

A

 Antidote for organophosphate insecticide poisoning

28
Q

 Blockade of thermoregulatory
sweating
 Can result to hyperthermia

A

“Atropine fever”

29
Q

 Dilation of the cutaneous vessels

of the arm, head, neck and trunk

A

“Atropine flush”

30
Q

NICOTINIC ANTAGONISTS
A. CLASSIFICATION
Subdivided into

 Act like competitive pharmacologic
antagonists
 First successful agents for the treatment
of hypertension

A
  1. GANGLION-BLOCKING DRUGS
31
Q
  1. GANGLION-BLOCKING DRUGS
A

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

32
Q

NICOTINIC ANTAGONISTS
A. CLASSIFICATION

 Adverse effects in hypertension are so
severe
 Both sympathetic and parasympathetic
are blocked

A
  1. GANGLION-BLOCKING DRUGS
33
Q
  1. GANGLION-BLOCKING DRUGS

 Adverse effects

A

Dry mouth
 Blurred vision
 Severe sexual dysfunction

34
Q

NICOTINIC ANTAGONISTS
A. CLASSIFICATION

 Important for producing complete
muscle skeletal relaxation in surgery
 Classified into two

A
  1. NEUROMUSCULAR-BLOCKING DRUGS
35
Q

NEUROMUSCULAR-BLOCKING DRUGS

 Tubocurarine is the prototype
 Competitive block at the end plate
nicotinic receptor

A

a. NONDEPOLARIZING GROUP

36
Q

NEUROMUSCULAR-BLOCKING DRUGS

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

A

a. NONDEPOLARIZING GROUP

37
Q

NEUROMUSCULAR-BLOCKING DRUGS

 Nicotinic agonists not antagonists that
cause flaccid paralysis
 Succinylcholine is the only member

A

b. DEPOLARIZING GROUP

38
Q

effect of nicotinic antagonists on the CNS

A

Sedation, tremor

39
Q

effect of nicotinic antagonists on the EYE

A

Mydriasis and cycloplegia

40
Q

effect of nicotinic antagonists on the GIT

A

Marked reduced motility, constipation

41
Q

effect of nicotinic antagonists on the GUT

A

Reduced contractility of the bladder, urinary

hesitancy, impairment of erection and ejaculation

42
Q

effect of nicotinic antagonists on the HEART

A

Vasodilator, antihypertensive, tachycardia

43
Q

effect of nicotinic antagonists on the BLOOD VESSELS

A

Reduction in arteriolar and venous tone, BP decrease,

orthostatic hypotension

44
Q

effect of nicotinic antagonists on the GLANDS

A

Reduction in salivation, lacrimation, sweating and

gastric secretion