Block 9 Pharm Anti Cholinergic W Exp Prt 1
Questions and Answers
- 1.
This drug is currently used in bronchospastic disorders
- A.
Atropine
- B.
Benztropine
- C.
Darifenacin
- D.
Glycopyrrolate
- E.
Homatropine
- F.
Ipratropium
- G.
Mecamylamine
- H.
Nicotine
- I.
Scopolamine
Correct Answer
F. IpratropiumExplanation
Ipratropium is currently used in bronchospastic disorders. It is an anticholinergic medication that helps to relax the airway muscles and improve airflow to the lungs. It is commonly used in conditions such as asthma and chronic obstructive pulmonary disease (COPD) to relieve symptoms like wheezing, shortness of breath, and coughing. By blocking the action of acetylcholine, a neurotransmitter that causes bronchial constriction, ipratropium helps to open up the airways and make breathing easier.Rate this question:
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- 2.
This drug can block M3 receptors only
- A.
Atropine
- B.
Benztropine
- C.
Darifenacin
- D.
Glycopyrrolate
- E.
Homatropine
- F.
Ipratropium
- G.
Mecamylamine
- H.
Nicotine
- I.
Scopolamine
Correct Answer
C. DarifenacinExplanation
Darifenacin is a selective antagonist of M3 receptors. M3 receptors are found in various tissues including smooth muscles, glands, and the central nervous system. By blocking M3 receptors, darifenacin inhibits the effects of acetylcholine, leading to relaxation of smooth muscles and decreased glandular secretions. This makes darifenacin useful in the treatment of overactive bladder, as it reduces bladder contractions and urinary frequency. The other options listed do not specifically target M3 receptors, making darifenacin the correct answer.Rate this question:
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- 3.
This drug can block Nn receptors only
- A.
Atropine
- B.
Benztropine
- C.
Darifenacin
- D.
Glycopyrrolate
- E.
Homatropine
- F.
Ipratropium
- G.
Mecamylamine
- H.
Nicotine
- I.
Scopolamine
Correct Answer
G. MecamylamineExplanation
Mecamylamine is the correct answer because it is a drug that specifically blocks Nn receptors. Nn receptors are a type of nicotinic acetylcholine receptor found in the autonomic ganglia and adrenal medulla. By blocking these receptors, mecamylamine inhibits the effects of acetylcholine, leading to a decrease in sympathetic and parasympathetic activity. This makes mecamylamine useful in the treatment of conditions such as hypertension and nicotine addiction. None of the other options listed have the same mechanism of action or specificity for Nn receptors.Rate this question:
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- 4.
This drug can increase epinephrine release from adrenal medulla
- A.
Atropine
- B.
Benztropine
- C.
Darifenacin
- D.
Glycopyrrolate
- E.
Homatropine
- F.
Ipratropium
- G.
Mecamylamine
- H.
Nicotine
- I.
Scopolamine
Correct Answer
H. NicotineExplanation
Nicotine is a drug that stimulates the release of epinephrine from the adrenal medulla. Epinephrine, also known as adrenaline, is a hormone that plays a crucial role in the body's "fight or flight" response. It increases heart rate, blood pressure, and blood sugar levels, preparing the body for intense physical activity. Nicotine, when consumed through smoking or other forms of tobacco use, activates the adrenal medulla, leading to the release of epinephrine. This can result in increased alertness, heightened senses, and a temporary increase in energy levels.Rate this question:
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- 5.
Which of the following molecular actions can result from the blockade of M3 receptors by antimuscarinic drugs in non-vascular smooth muscle?
- A.
Less negative resting membrane potential
- B.
Binding of Ca++ to troponin C
- C.
Increased concentration of cytosolic calcium
- D.
Decreased synthesis of intracellular IP3
- E.
Direct opening of K+ channels
Correct Answer
D. Decreased synthesis of intracellular IP3Explanation
The postreceptor mechanism triggered by activation of M3 receptors is the stimulation of
phospholipase C which in turn increases the synthesis of IP3. By blocking M3 receptors the
opposite occurs.
A) When M3 receptors are activated by acetylcholine the membrane potential of a smooth
muscle becomes less negative, that is the muscle is more excitable. This explains the increase
in tonic tension and in the number of contractions brought about by acetylcholine. By blocking
M3 receptors antimuscarinic drugs cause the opposite, that is the resting membrane potential
becomes more negative, not less negative, and the muscle is less excitable.
B) In smooth muscle CA++ binds to calmodulin, not to troponin C.
C) Since the synthesis of intracellular IP3 is decreased concentration of cytosolic calcium is
decreased, not increased.
E) Potassium channels are mainly regulated by M2 receptors, not by M3 receptors.Rate this question:
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- 6.
Which of the following is an effects of atropine upon the respiratory system?
- A.
Increased contraction of airway smooth muscle
- B.
Increased secretion of bronchial glands
- C.
Decreased mucociliary clearance
- D.
Decreased pulmonary vital capacity
- E.
Decreased diaphragmatic performance
Correct Answer
C. Decreased mucociliary clearanceExplanation
Answer: C
Antimuscarinic drugs (except ipratropium and tiotropium) decrease mucociliary clearance, an
effect that contraindicates these drugs in asthmatic patients.
A, B, D) Actually antimuscarinic drugs do the opposite.
E) Diaphragm is a skeletal muscle and therefore is not under the control of the autonomic
nervous system.Rate this question:
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- 7.
Which of the following is a common side effect of quaternary ammonium antimuscarinic drugs?
- A.
Urge incontinence
- B.
Drowsiness
- C.
Difficulty in near vision
- D.
AV block
- E.
Hallucinations
Correct Answer
C. Difficulty in near visionExplanation
Answer: C
Quaternary ammonium antimuscarinic drugs mainly block muscarinic receptors but also exhibit a
significant blocking activity at ganglionic Nn receptors. The blockade of M3 receptors in the
ciliary muscle and of Nn receptors in the ciliary ganglion cause cycloplegia with loss of
accommodation for near vision.
A) Urge incontinence is due to contraction of the detrusor muscle. By blocking M3 receptors
antimuscarinic drugs actually cause relaxation, not contraction, of the detrusor muscle.
B, E) Quaternary ammonium antimuscarinic drugs do not cross the blood brain barrier so these
effects are unlikely.
D) By blocking M2 receptors in the heart antimuscarinic drugs increase AV conduction, so AV
block is unlikelyRate this question:
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- 8.
Antimuscarinic drugs usually increase the heart rate because they can counteract which of the following acetylcholine-induced actions?
- A.
Release of nitric oxide
- B.
Opening of K+ channels in SA node
- C.
Decrease in cardiac contractility
- D.
Opening of Na+ channels in ganglionic neurons
- E.
Activation of cardiac presynaptic autoreceptors
Correct Answer
B. Opening of K+ channels in SA nodeExplanation
Answer: B
By activating M2 receptors acetylcholine opens K+ channels in the SA node. This increases the
outward K+ current and the membrane becomes hyperpolarized. The result is a decrease in
firing rate of the SA node. By blocking M2 receptors antimuscarinic drugs counteract the
acetylcholine-induced opening of K+ channels in the SA node. The firing rate of the SA node is
increased so causing an increase in heart rate.
A) Acetylcholine-induced release of nitric oxide causes vasodilation which could lead to reflex
tachycardia. By counteracting this action antimuscarinic drugs would decrease, not increase ,the
heart rate.
C) Antimuscarinic drugs can counteract acetylcholine-induced decrease in cardiac contractility,
but this has nothing to do with the increase in heart rate.
D) Acetylcholine-induced Opening of Na+ channels in ganglionic neurons is mediated by the
activation of Nn receptors. Antimuscarinic drugs have weak or negligible blocking activity on
these receptors.
E) The blockade of presynaptic autoreceptors increases the release of acetylcholine from
cholinergic terminals. This would decrease, not increase, the heart rate.Rate this question:
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- 9.
Which of the following statements correctly pairs the antimuscarinic drug with one of its common adverse effects?
- A.
Atropine - cough
- B.
Darifenacin - constipation
- C.
Glycopyrrolate -insomnia
- D.
Ipratropium -restlessness
- E.
Scopolamine - impairment of far vision
Correct Answer
B. Darifenacin - constipationExplanation
Answer: B
Darifenacin is a selective M3 receptor antagonist. The drug-induced decrease in intestinal
peristalsis can lead to constipation.
A) By causing bronchodilation atropine can actually relieve cough.
C, D) Ipratropium and glycopyrrolate are quaternary ammonium compound that do not enter the
brain. Therefore central adverse effects are quite unlikely.
E) By causing cycloplegia scopolamine impairs the near, not the far vision.Rate this question:
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- 10.
Antimuscarinic drugs are contraindicated, or should be used with caution, in which of the following disease states?
- A.
Irritable bowel syndrome
- B.
Sialorrhea
- C.
Travelers’ diarrhea
- D.
Urinary urge incontinence
- E.
Sinus bradycardia
- F.
Ulcerative colitis
Correct Answer
F. Ulcerative colitisExplanation
Answer: F
Antimuscarinic drugs decrease intestinal peristalsis. In case of severe inflammatory bowel
diseases, this can cause toxic megacolon.
A, B, C, D, E) These options are indications, not contraindications, to the use of antimuscarinic
drugsRate this question:
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- 11.
Atropine can most effectively counteract which of the following drug-induced effects?
- A.
Physostigmine-induced sweating
- B.
Epinephrine-induced increased in blood pressure
- C.
Nicotine-induced increase in peripheral vascular resistance
- D.
Prazosin-induced reflex tachycardia
- E.
Scopolamine-induced sleepiness
Correct Answer
A. Physostigmine-induced sweatingExplanation
Answer: A
Physostigmine is a cholinesterase inhibitors and therefore it can increase the availability of
acetylcholine at cholinergic neuroeffector junctions. Activation of M3 receptors in sweat glands
promotes sweating. By blocking these receptors atropine can counteract this action.
B) Epinephrine increase blood pressure by activating alpha-1 and beta-1 receptors. These
receptors are not affected by atropine.
C) Nicotine can increase peripheral vascular resistance by activating Nn receptors at
sympathetic ganglia. Atropine has negligible effects on Nn receptors.
D) Prazosin can cause reflex tachycardia by blocking alpha-1 receptors which in turn decreases
the blood pressure. Atropine actually can cause tachycardia and therefore it can increase, not
counteract, the action of prazosin.
E) Scopolamine and atropine are belladonna alkaloids with very close pharmacological
properties. Therefore the effects of the two drugs enhance, not antagonize, each other.Rate this question:
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- 12.
A 32-year-old woman suffering from irritable bowel syndrome was prescribed glycopyrrolate. The blockade of which of the following pairs of receptors best explains the mechanism of the therapeutic effect of the drug in this patient?
- A.
Beta-2 and Nm
- B.
M2 and Nn
- C.
M3 Nn
- D.
Alpha-1 and M2
- E.
M1 M3
Correct Answer
C. M3 NnExplanation
Answer: C
Glycopyrrolate is a quaternary ammonium antimuscarinic drug. These drugs relax the intestinal
smooth muscle and are often given to patients with irritable bowel syndrome in order to relieve
the hyperactivity of the gut. Quaternary ammonium antimuscarinic drugs mainly block muscarinic
receptors but also exhibit a significant blocking activity of ganglionic Nn receptors. Both the
blockade of M3 receptors in the gastrointestinal smooth muscle and the blockade of the Nn
receptors in the ganglia of myenteric plexus likely contribute to the relaxation of the smooth
muscle.
A, B, D, E) (see explanation above).Rate this question:
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- 13.
A 85-year-old man resident of a nursing facility recently developed urinary incontinence. He was treated with darifenacin, which was able to decrease the urge to urinate and the pain associated with it. Which of the following molecular mechanism of action most likely mediated the therapeutic effect of the drug in this patient?
- A.
Decreased potassium efflux from cells of detrusor muscle
- B.
Decreased availability of cytosolic calcium in cells of detrusor muscle
- C.
Activation of alpha-1 receptors in bladder internal sphincter
- D.
Activation of M3 receptors in bladder internal sphincter
- E.
Increased sodium influx into cells of detrusor muscle
Correct Answer
B. Decreased availability of cytosolic calcium in cells of detrusor muscleExplanation
Answer: B
Darifenacin is a selective M3 antagonist currently used to treat urge incontinence.. Activation of
M3 receptors by acetylcholine increases the synthesis of IP3 which in turn triggers the release of
calcium from storage vesicles. Blockade of M3 receptors does the opposite, so the availability of
cytosolic calcium in smooth muscle cells is decreased and the muscle relaxes. Relaxation of the
detrusor muscle of the bladder relieves the urge to urinate.
A) This effect is caused by blockade of M2 receptors, not by blockade of M3 receptors.
C, D, E) Antimuscarinic drugs do not cause any of these effects.Rate this question:
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- 14.
A 5-year-old boy was prescribed ophthalmic drops in order to prepare the eye for measurement of refractive errors. One hour after the first administration the boy showed mental confusion, restlessness, incoherence and hallucinatory behavior. His pulse rate was 120 bpm. Which of the following drugs was most likely administered?
- A.
Phenylephrine
- B.
Epinephrine
- C.
Atropine
- D.
Timolol
- E.
Apraclonidine
Correct Answer
C. AtropineExplanation
Answer: C
Antimuscarinic drugs are sometime used to prepare the eye for measurement of refractive
errors. Even if atropine is administered topically, it can pass into the nasolacrimal duct and can
be absorbed from the nasal mucosa. Children are especially sensitive to the effects of
antimuscarinic drugs and may exhibit the classic central and cardiovascular symptoms of
atropine overdose, like in the present case.
B) This drug can also be absorbed from the nasal mucosa and could transiently increase the
heart rate, but it would cause negligible central effects since it does not enter the brain.
A, D, E) These drugs would cause a decrease, not an increase, in heart rate.Rate this question:
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- 15.
A 48-year-old man was admitted to the coronary unit with an acute myocardial infarction. He had been suffering from a left bundle branch block which now changed into a Mobiz 1 AV block. His heart rate decreased from 70 bpm to 48 bpm. Which of the following drugs would be appropriate to manage the patient’s bradycardia?
- A.
Epinephrine
- B.
Propranolol
- C.
Clonidine
- D.
Phenylephrine
- E.
Atropine
Correct Answer
E. AtropineExplanation
Answer: E
When complicating an inferior myocardial infarction, AV block often results from an increased
parasympathetic tone and usually respond to atropine. Sometimes the block resolve
spontaneously, but in the present case the block must be treated since the heart rate is too low
for a sufficient cardiac output.
A) Epinephrine can increase the heart rate but is usually contraindicated in myocardial
infarction, since it increases the heart workload and oxygen consumption. Moreover in this case
bradycardia is due to acetylcholine. Epinephrine is a physiologic antagonist of acetylcholine
whereas atropine is a pharmacological antagonist. As a general rule, pharmacological
antagonism is much better than physiologic antagonism, in most cases.
B, D, E) These drugs are actually contraindicated because they decrease, not increase, the
heart rate.Rate this question:
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Mar 22, 2023Quiz Edited by
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Jun 03, 2012Quiz Created by
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