1996  EXAM 3

Select the letter of the BEST single answer.

17. Reversal agents are ______ which act by ______.

a. antimuscarinics; antagonizing effects of acetylcholine at nicotinic cholinergic postjunctional receptors

b. anticholinergics; inhibiting pseudocholinesterase

c. anticholinesterases; inhibiting acetylcholinesterase, thereby favoring acetylcholine binding to the beta subunits of the nicotinic cholinergic postjunctional receptors

d. none of the above

18. Edrophonium is not recommended for using to reverse neuromuscular blockade that is considered a ‘deep’ block, i.e., 0-1 of 4 twitches on the train-of-four. A plausible explanation for this recommendation is that:

A.     B.     C.     D.

a. edrophonium’s electrostatic attachment to the anionic site on acetylcholinesterase is a weak attachment

b. edrophonium’s formation of a carbamyl-ester complex at the esteratic site on acetylcholinesterase is a weak attachment

c. edrophonium works via irreversible inhibition of acetylcholinesterase

d. edrophonium’s clinical duration of action is shorter than either pyridostigmine or neostigmine

19. Pyridostigmine features the following pharmacokinetic characteristics:

a. onset is delayed; duration is 60 min; reversal dose is 0.15-0.35 mg/kg

b. onset is rapid; duration is 90 min; reversal dose is 0.035-0.070 mg/kg

c. onset is delayed; duration is 90 min; reversal dose is 0.15-0.35 mg/kg

d. onset is intermediate; duration is 60 min; reversal dose is 0.5-1.0 mg/kg

20. Why is an antimuscarinic administered along with an anticholinesterase in reversing non-depolarizing neuromuscular blockade?

a. in order to offset the decreased heart rate

b. muscarinic effects are evoked by lower concentrations of acetylcholine than are required for producing nicotinic effects at the autonomic ganglia and the neuromuscular junction

c. anticholinesterases produce greater effects at the muscarinic receptors than at the nicotinic cholinergic postjunctional receptors

d. acetylcholine does not work at the nicotinic cholinergic postjunctional receptors without the presence of an antimuscarinic in the plasma

21. Of the antimuscarinic agents, ______ raises the heart rate the most, _______ produces no sedation, and ________ is the most effective antisialogogue.

a. atropine; glycopyrrolate; scopolamine

b. glycopyrrolate; atropine; scopolamine

c. scopolamine; glycopyrrolate; atropine

d. none of the above

22. Glycopyrrolate can cause significant bradycardia when administered at the same time as edrophonium due to glycopyrrolate's ______.

a. weak antimuscarinic effects on the cardiac muscarinic receptors

b. longer duration of action than edrophonium

c. slower onset than edrophonium

d. weak peripheral muscarinic receptor agonist action at lower doses

23. When introduced in the early 1980s, the new intermediate-acting non-depolarizing neuromuscular blockers vecuronium and atracurium rapidly gained popularity over the long-acting non-depolarizing neuromuscular blockers largely due to:

a. lower cost and lower intubating doses

b. absence of histamine release and absence of cardiovascular effects

c. efficient clearance mechanisms and significantly less cumulative effects

d. monoquaternary steroid-based chemical structures

24. Due to its long, slender, flexible structure (which is 2 acetylcholine molecules back-to-back), succinylcholine can bind to and _______ cholinergic receptors, whereas non-depolarizing neuromuscular blockers ________ cholinergic receptors.

a. activate; cannot activate

b. inactivate; activate

c. repolarize; depolarize

d. antagonize; are agonists at