1
USMLE
USMLE step 3 - drug MOA
(indications) Exam Questions
with Correct Verified Solutions
100% Guaranteed Pass
1. Ondansetron (Zofran) - ANS ✓5HT-3 antagonist at chemoreceptor
trigger zone --> down-regulate input to vomiting center in lateral
medulla
2. Clozapine, risperidone, olanzapine, quetiapine - ANS ✓5HT-2
antagonist (atypical antipsychotic)
3. Chlorpromazine, thioridazine - ANS ✓low-potency D2 antagonist
(antipsychotic)
4. Haloperidol, fluphenazine - ANS ✓high-potency D2 antagonist
(antipsychotic)
5. Heparin - ANS ✓ACTIVATES ANTITHROMBIN --> dec thrombin and
clotting factor Xa (anticoagulation for pts with PE, MI, stroke, etc.)
6. Streptokinas, tpa - ANS ✓converts plasminogen to plasmin -->
cleavage of thrombin and fibrin
7. Aspirin - ANS ✓irreversible COX inhibition --> dec thromboxane
USMLE step 3 - drug MOA (indications)
, 2
USMLE
8. Clopidogrel - ANS ✓irreversibly blocks ADP receptors --> dec
Gp2b/3a expression
9. Warfarin - ANS ✓blocks vitamin K dependent carboxylation of
clotting factors
10. Nitroglycerine - ANS ✓NO stimulates guanylate cyclase --> inc
cgmp --> activation of protein kinases --> dec intracellular Ca, inc
MLCK --> smooth muscle relaxation --> dilation of arteries > veins -->
DECREASED PRELOAD (angina, take with beta blocker to minimize
reflex tachycardia)
11. Albuterol, terbutaline, metaproterenol, salmeterol,
formoterol - ANS ✓β2 agonists (asthma)
12. Ipratropium - ANS ✓muscarinic antagonists (block
vasoconstriction in asthma)
13. Beclomethasone, prednisone, other corticosteroids - ANS
✓• inhibit phospholipase A --> block arachidonic acid cascade
• inactivate NF-κβ --> dec tnfα
(asthma)
14. Acyclovir - ANS ✓• activated by viral thymidine kinase
• guanosine analog --> chain elongation termination
• inhibition of viral DNA polymerase
(HSV, VZV, EBV)
USMLE step 3 - drug MOA (indications)
USMLE
USMLE step 3 - drug MOA
(indications) Exam Questions
with Correct Verified Solutions
100% Guaranteed Pass
1. Ondansetron (Zofran) - ANS ✓5HT-3 antagonist at chemoreceptor
trigger zone --> down-regulate input to vomiting center in lateral
medulla
2. Clozapine, risperidone, olanzapine, quetiapine - ANS ✓5HT-2
antagonist (atypical antipsychotic)
3. Chlorpromazine, thioridazine - ANS ✓low-potency D2 antagonist
(antipsychotic)
4. Haloperidol, fluphenazine - ANS ✓high-potency D2 antagonist
(antipsychotic)
5. Heparin - ANS ✓ACTIVATES ANTITHROMBIN --> dec thrombin and
clotting factor Xa (anticoagulation for pts with PE, MI, stroke, etc.)
6. Streptokinas, tpa - ANS ✓converts plasminogen to plasmin -->
cleavage of thrombin and fibrin
7. Aspirin - ANS ✓irreversible COX inhibition --> dec thromboxane
USMLE step 3 - drug MOA (indications)
, 2
USMLE
8. Clopidogrel - ANS ✓irreversibly blocks ADP receptors --> dec
Gp2b/3a expression
9. Warfarin - ANS ✓blocks vitamin K dependent carboxylation of
clotting factors
10. Nitroglycerine - ANS ✓NO stimulates guanylate cyclase --> inc
cgmp --> activation of protein kinases --> dec intracellular Ca, inc
MLCK --> smooth muscle relaxation --> dilation of arteries > veins -->
DECREASED PRELOAD (angina, take with beta blocker to minimize
reflex tachycardia)
11. Albuterol, terbutaline, metaproterenol, salmeterol,
formoterol - ANS ✓β2 agonists (asthma)
12. Ipratropium - ANS ✓muscarinic antagonists (block
vasoconstriction in asthma)
13. Beclomethasone, prednisone, other corticosteroids - ANS
✓• inhibit phospholipase A --> block arachidonic acid cascade
• inactivate NF-κβ --> dec tnfα
(asthma)
14. Acyclovir - ANS ✓• activated by viral thymidine kinase
• guanosine analog --> chain elongation termination
• inhibition of viral DNA polymerase
(HSV, VZV, EBV)
USMLE step 3 - drug MOA (indications)
