Prepared by M.L. Thompson, Ph. D., Dept. of General Dentistry, Tufts Dental School
C:\Documents and Settings\mthomp01\Desktop\pharm2007 shortcuts\Boards2005.doc
17
Analgesics- NSAIDS:
1. Mechanism of action questions regarding analgesic, antipyretic and
effects on bleeding:
Analgesic effects: aspirin inhibits the synthesis of prostaglandins
Antipyretic effects: aspirin inhibits PG synthesis in the
hypothalamic temperature regulation center
Bleeding time: inhibit synthesis of thromboxane A2 preventing
platelet synthesis
2. A 2nd type of question has to do with pharmacological or toxic effects
of aspirin: you get to pick which of the list is or is not associated
with aspirin. Therapeutic effects of aspirin include pain relief,
antipyretic effects, antirheumatic and anti-inflammatory effects.
Adverse or toxic effects include all of the following: occult bleeding
from the GI tract, tinnitus, nausea and vomiting, acid-base
disturbance or metabolic acidosis, decreased tubular reabsorption
of uric acid, salicylism, delirium, hyperventilation, etc.
3. A third type of question focuses on the difference between 1) aspirin
and acetaminophen, 2) aspirin and other anti-inflammatories like
prednisone, and 3) between aspirin and ibuprofen:
1) Acetaminophen lacks anti-inflammatory activity, is hepatotoxic,
and does not cause GI upset
2) Anti-inflammatories like prednisone, hydrocortisone,
triamcinolone etc. are steroids and do not act primarily by PG
inhibition
3) Ibuprofen causes much less GI irritation
4) Diflunisal (Dolobid) has a longer half-life than aspirin,
acetaminophen and ibuprofen
4. Newer versions of the boards have questions about COX-2
inhibitors like vioxx. (Which of the following is a COX-2
inhibitor?)
5. These old questions focus a lot on aspirin. Nowadays,
acetaminophen and ibuprofen are used much more
commonly than aspirin, because of the many side effects of
aspirin that turn up in these kinds of questions. So since
aspirin is the comparator prototype drug, reviewing these
questions are still useful.
1) But expect newer questions asking you to know:
a. Acetaminophen causes liver toxicity, especially
when combined with alcohol or taken in excess
of 4 gr/day.
b. Acetaminophen is the drug of choice for the
feverish child (they usually ask the reverse,
which is which drug should be avoided in the
feverish child (aspirin- increased risk of Reye’s
syndrome)
Frequently asked questions on NSAIDS
4. The therapeutic effect of the salicylates is explained on the basis of the
ability of the drug to
a.
Activate autonomic reflexes
b.
Uncouple oxidative phosphorylation
c.
Inhibit the synthesis of prostaglandins
d.
Competitively antagonize prostaglandins at the receptor site
(c)
5. The mechanism of the antipyretic action of salicylates probably results
from
a.
Inhibition of prostaglandin synthesis in the CNS affecting
hypothalamic temperature regulation
b.
Inhibition of bradykinin in the periphery leading to sweating
c.
Depression of oxidative enzymes leading to decreased heat
production
d.
Suppression of cholinergic mediators in the hypothalamus
e.
Stimulation of norepinephrine in the hypothalamus
(a)
6. The antipyretic action of salicylates is explained in part by
a. Analgesia leading to sedation
b. Increased blood flow through the hypothalamus
c. Cutaneous vasodilation leading to increased heat loss
d. Depression of oxidative processes leading to decreased heat
production
(c)
7. The locus of action of aspirin's central antipyretic effect is the
a.
Brain stem
b.
Hypothalamus
c.
Basal ganglia
d.
Limbic system
e.
Cerebral cortex
(b) memorization question- remember antipyresis means
antifever. Temperature regulation center is in the hypothalamus.
8. A patient who has been taking large quantities of aspirin might show
increased postoperative bleeding because aspirin inhibits
a.
Synthesis of thromboxane A2 and prevents platelet
aggregation
b.
Synthesis of prostacyclin and prevents platelet aggregation
c.
Synthesis of prostaglandin and prevents production of blood
platelets
d.
Thrombin and prevents formation of the fibrin network
e.
G.I. absorption of vitamin K and prevents synthesis of blood
clotting factors
(a) The first fact you must remember is that aspirin prevents
platelet aggregation- this limits your choices to (a) and (b). They
hope to confuse you by using prostacylin, but of course you
know that this is wrong immediately, the right word is
prostaglandin, as in (c), but you have already eliminated that
choice because it doesn't mention prevention of platelet
aggregation. Thus, even if you didn't remember that
thromboxane A2 induces platelet aggregation, and aspirin
blocks this action, you could get the answer by elimination. (d) is
how heparin works, while (e) is how coumarin works.
9. Anti-inflammatory agents, such as aspirin, interfere with hemostasis by
a.
Activating antithrombin
b.
Preventing vasoconstriction
c.
Inhibiting thrombin generation
d.
Inhibiting platelet aggregation
e.
Inhibiting polymerization of fibrin
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