Question 1

Which of the following is a muscarinic antagonist selective for the urinary tract and therefore is used to treat urge incontinence?&#10;A) Atropine&#10;B) Bethanechol&#10;C) Tolterodine&#10;D) Ipratropium&#10;E) Glycopyrrolate

Accepted Answer

Tolterodine is a muscarinic antagonist selective for the urinary tract and is used to treat urge incontinence by decreasing the overactivity of the detrusor muscle of the bladder. Atropine, Ipratropium, and Glycopyrrolate are non-selective muscarinic antagonists used to treat a variety of conditions such as bradycardia, asthma, and excessive sweating. Bethanechol is a muscarinic agonist used to stimulate the bladder and gastrointestinal tract.

Question 2

Which of the following is a NOT a probable effect produced by muscarinic stimulation?&#10;A) Decreased heart rate&#10;B) Pupillary dilatation&#10;C) Increased salivation&#10;D) Urinary sphincter relaxation&#10;E) Increased gut motility

Accepted Answer

Muscarinic cholinergic stimulation via the parasympathetic nervous system stimulates contraction of the iris sphincter muscle, thereby producing papillary constriction (miosis).

Question 3

A 58-year-old woman is given scopolamine to treat postoperative nausea. She then becomes extremely sedated and unresponsive. The following medication would be most effective in reversing the central nervous system side effects of scopolamine:

A) Physostigmine
B) Edrophonium
C) Neostigmine
D) Pyridostigmine
E) Pralidoxime (2-PAM)

Physostigmine

Accepted Answer

Scopolamine is a competitive cholinergic receptor antagonist. Physostigmine is an acetylcholinesterase inhibitor that acts to increase the concentration of acetylcholine and thereby overcome antagonism of its effects. Physostigmine has a tertiary amine structure and is less polarized than edrophonium, neostigmine, and pyridostigmine. Therefore physostigmine more effectively crosses the blood-brain barrier to counteract central nervous system side effects.

Deck 10: Drugs Affecting the Parasympathetic Nervous System and Autonomic Ganglia