Flashcards in CHOLINOCEPTOR-BLOCKING DRUGS Deck (44)
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1
MUSCARINIC ANTAGONISTS
Selective
Only a few receptor-selective
--- antagonists have reached clinical trial
Pirenzipine
M1
2
MUSCARINIC ANTAGONISTS
A. CLASSIFICATION AND PHARMACOKINETICS
Subdivided into
Most of the drugs in the market
2. Nonselective
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.
MUSCARINIC
NICOTINIC
4
Cholinoreceptor antagotists are divided into two:
blocks parasympathetic autonomic discharge. Atropine is the prototype of these drugs.
Muscarinic
5
Cholinoreceptor antagotists are divided into two:
competitively block the actions of acetylcholine at nicotinic receptors of both parasympathetic and sympathetic ganglia.
Nicotinic
6
Prototype nonselective muscarinic
blocker
Derivative of a deadly night shade
Atropa belladona and other plants
ATROPINE
7
Tertiary amine
Relatively lipid soluble
Crosses membrane barriers
Well distributed in the CNS and other
organs
ATROPINE
8
Eliminated partially by metabolism in
the liver
Partially by renal excretion
Elimination half-life is 2 hours
ATROPINE
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
ATROPINE
10
organ affected by muscarinic antagonists
Sedation, hallucination, drowsiness, antimotion sickness action, antiparkinson action, amnesia
CNS
11
organ affected by muscarinic antagonists
Mydriasis, cyclopegia, lacrimal glands become dry and sandy
eye
12
organ affected by muscarinic antagonists
Initial bradycardia at low doses then tachycardia
heart
13
organ affected by muscarinic antagonists
Bronchodilation, decrease in bronchial secretions
Respiratory
14
organ affected by muscarinic antagonists
Relaxation, decrease motility, antidiarrheal, prolongs gastric
emptying time
GIT
15
organ affected by muscarinic antagonists
Relaxation of the bladder wall, urinary retention
gut
16
organ affected by muscarinic antagonists
Decrease secretion, salivation, lacrimation, sweating
gland
17
organ affected by muscarinic antagonists
None
skeletal muscle
18
EFFECTS OF INCREASING DOSE OF
ATROPINE
(7)
Decrease bronchial and salivary
secretions
Decrease sweating
Mydriasis
Tachycardia
Urinary hesitancy
Decrease intestinal motility
Decrease gastric secretion
19
MUSCARINIC ANTAGONISTS
D. CLINICAL USES
1. CNS
Parkinson’s disease
Decrease dopamine and cholinergic
transmission
Benztrypine, biperiden,
trihexyphenidyl
20
MUSCARINIC ANTAGONISTS
D. CLINICAL USES
2. EYE
Used to dilate the pupil
Paralyze accommodation
21
D. CLINICAL USES
1. CNS
Widely distributed
Excreted rapidly
Standard therapy for motion sickness
Dicyclomine
22
Used to reduce airway secretions
during general anesthesia
IV atropine
23
Quaternary antimuscarinic agent
Used by inhalation
Promote bronchodilation
Asthma and COPD
Ipratropium
24
Used for peptic ulcer
M1-selective inhibitor pirenzipine
25
Used to reduce acid secretion
Not as effective as the H
2 antagonists
Atropine
26
MUSCARINIC ANTAGONISTS
D. CLINICAL USES
5. GUT
Used to reduce urgency in mild cystitis
Used to reduce bladder spasm following
urologic surgery
Treatment of enuresis
27
MUSCARINIC ANTAGONISTS
D. CLINICAL USES
6. CHOLINERGIC POISONING
Antidote for organophosphate insecticide poisoning
28
Blockade of thermoregulatory
sweating
Can result to hyperthermia
“Atropine fever”
29
Dilation of the cutaneous vessels
of the arm, head, neck and trunk
“Atropine flush”
30
