Drug Action II Exam 3 Review: Autonomic Nervous System & Cranial Nerves

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Questions and Answers

Which of the following is the primary reason why scopolamine has greater central nervous system (CNS) effects compared to atropine?

Scopolamine is more lipophilic and can cross the blood-brain barrier more easily (correct)
Scopolamine is a more potent muscarinic antagonist
Scopolamine has a longer duration of action
Scopolamine has a higher affinity for muscarinic receptors

Which of the following is the primary mechanism by which tolterodine, a muscarinic antagonist, exerts its effects in the treatment of urinary incontinence?

Longer half-life due to shielding of the ester group
Uroselective action that preferentially targets the bladder
Nonselective blockade of M2 and M3 muscarinic receptors (correct)
Selective blockade of M2 muscarinic receptors in the bladder

Which of the following is the primary mechanism by which solifenacin, a muscarinic antagonist, exhibits a longer half-life compared to other muscarinic antagonists used for urinary incontinence?

Enantiomeric selectivity, with the R-enantiomer being more potent
Aromatic rings that protect the ester group from hydrolysis (correct)
Selective blockade of M3 receptors in the bladder
Uroselective action that preferentially targets the bladder

How do muscarinic antagonists, such as ipratropium and tiotropium, help alleviate pulmonary constriction in conditions like COPD or asthma?

By selectively blocking M3 receptors in the bronchial smooth muscle, preventing cholinergic-mediated bronchoconstriction (D) Signup and view all the answers

What is the primary reason why tropicamide and cyclopentolate, ophthalmic muscarinic antagonists, have a shorter duration of action compared to atropine?

They are more rapidly metabolized by esterases compared to atropine (C) Signup and view all the answers

Which of the following is the primary mechanism by which neuromuscular blockers, such as competitive non-depolarizing blocking agents (CNMBs), interfere with neuromuscular transmission?

By competitively binding to and blocking the postsynaptic nicotinic acetylcholine receptors (A) Signup and view all the answers

How does the quaternary ammonium structure of ipratropium contribute to its mechanism of action as a muscarinic antagonist?

The quaternary ammonium structure limits the systemic absorption of ipratropium, leading to a more localized, site-specific effect (A) Signup and view all the answers

What is the primary advantage of the thiophene ring structure in the muscarinic antagonist tiotropium compared to ipratropium?

The thiophene ring protects the ester group of tiotropium from hydrolysis, resulting in a longer duration of action (D) Signup and view all the answers

Flashcards

Why does scopolamine have greater CNS effects than atropine?

Scopolamine is more lipophilic, allowing it to cross the blood-brain barrier more easily, leading to greater CNS effects compared to atropine.

Tolterodine's mechanism for urinary incontinence

Tolterodine exerts its effects by nonselectively blocking M2 and M3 muscarinic receptors, which reduces urinary incontinence.

Why does solifenacin have a longer half-life?

Solifenacin has aromatic rings that protect the ester group from hydrolysis, resulting in a longer half-life compared to other muscarinic antagonists.

How do ipratropium and tiotropium help with COPD/asthma?

Muscarinic antagonists like ipratropium and tiotropium alleviate pulmonary constriction by selectively blocking M3 receptors in bronchial smooth muscle, which prevents cholinergic-mediated bronchoconstriction.