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USMLE Step 1 Pharmacology

Subjects : health-sciences, usmle-step-1

Instructions:

Answer 50 questions in 15 minutes.
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Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. What is the MOA for the Tetracyclines?
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic
Prevents the release of Ca from SR of skeletal muscle
1. Hot flashes 2. Ovarian enlargement 3. Multiple simultaneous pregnancies 4. Visual disturbances
physostigmine

2. What is the MOA for Carbenicillin - Piperacillin - and Ticarcillin?
- Corticosteroids - heparin
- Chlorpromazine - thioridazine - haloperidol
Same as penicillin. Extended spectrum antibiotics
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.

3. What patients are at risk for life threatening hypotension When taking Sildenafil (Viagra)?
Those patients who are taking nitrates.
Teratogenic - Carcinogenic - Confusion - Headaches
Edrophonium
Cephalosporin: 1) has a 6 member ring attached to the Beta lactam instead of a 5 member ring 2)has an extra functional group ( attached to the 6 member ring)

4. What are the major toxic side effects of Imipenem/cilastatin?
post MI and digitalis induced arrhythmias
Benzodiazepine.
GI distress - Skin rash - and Seizures at high plasma levels
pulmonary edema - dehydration

5. Ganciclovir associated toxicities?
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity
Gemfibrozil - Clofibrate
Topical and Oral - for Oral Candidiasis (Thrush)
Tricyclic antidepressant.

6. Resistance mechanisms for Sulfonamides
Pyridoxine (B6) administration
Sucralfate cannot work in the presence of antacids or H2 blockers because it requires an acidic environment to polymerize.
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis
Cimetidine is a potent inhibitor of P450; it also has an antiandrogenic effect and decreases renal excretion of creatinine. Other H2 blockers are relatively free of these effects.

7. A fellow passenger on a Carnival cruise ship looks pale and diaphoretic - What antimuscarinic agent would you give them?
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.
Pentamidine
Increases coumadin metabolism
scopolamine

8. For Heparin What is the Ability to inhibit coagulation in vitro
Yes
- Tricyclic antidepressants
Neomycin
With supplemental Folic Acid

9. Mannitol - mechanism?
compensatory tachycardia - fluid retention - lupus - like syndrome
Penicillin - Ampicillin - Ticarcillin - Pipercillin - Imipenem - Aztreonam - Cephalosporins
Dermatophytes (tinea - ringworm)
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow

10. What is the category of drug names ending in - olol (e.g. Propranolol)
Meningitis (H. influenza - N. meningitidis - S. pneumoniae) - Conserative treatment due to toxicities
Penicillin - G
- N- acetylcystine
Beta antagonist.

11. What is the category - mechanism of action - and particular use of beclomethasone and prednisone in Asthma treatment?
Corticosteroids; prevent production of leukotrienes from arachodonic acid by blocking phospholipase A2. Drugs of choice in a patient with status asthmaticus (in combination with albuterol.)
cholestyramine - colestipol
ACIDazolamide' causes acidosis
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis

12. Which drug(s) cause this reaction: Tendonitis and rupture?
HTN - CHF - calcium stone formation - nephrogenic DI.
- Fluoroquinolones
Early myocardial infarction.
Carbachol - pilocarpine - physostigmine - echothiophate

13. Ethacrynic Acid - clinical use?
Diuresis in pateints with sulfa allergy
- Acetaldehyde - Nausea - vomiting - headache - & hypotension
GI distress - Tooth discoloration and Inhibition of bone growth in children - Fanconi's syndrome - Photosensitivity
increase AP duration - increase ERP - increase QT interval - for use When other arrhythmics fail

14. Does Ampicillin or Amoxicillin have a greater oral bioavailability?
AmOxicillin has greater Oral bioavailability
cross - allergenic
Carbachol - pilocarpine - physostigmine - echothiophate
- Alkalating agents+cisplatin - Doxorubicin+Dactinomycin - Bleomycin - Etoposide

15. What parasitic condition is treated with Ivermectin?

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16. What is the mechanism of action of Ticlopidine - Clopidogrel
Megaloblastic anemia - Leukopenia - Granulocytopenia
Inhibits Viral DNA polymerase
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.
Vd= (Amt. of drug in body/ Plasma drug conc.)

17. Why are albuterol and terbutaline effective in tx of acute asthmatic attacks?
Mycobacterium tuberculosis - the only agent used as solo prophylaxis against TB
increase AP duration - increase ERP - increase QT interval - for use When other arrhythmics fail
These B-2 agonists cause respiratory smooth muscle to relax.
Babiturate.

18. How does a noncompetitive antagonist effect an agonist?
With an amino acid change of D- ala D- ala to D- ala D- lac
Liver
Pentavalent Antimony
- Shifts the curve down - reduces Vmax

19. What is the MOA of Polymyxins?
severe hypertension - CHF
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents
1)Binds penicillin - binding proteins 2) Blocks transpeptidase cross - linking of cell wall 3) Activates autolytic enzymes
Buy AT 30 - CELL at 50'

20. List the specific antidote for this toxin: Benzodiazepines
GI discomfort
- Flumazenil
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic
Sildenafil fills the penis

21. What are Amantadine - associated side effects?
Quinolones
Hypersensitivity reactions
Ataxia - Dizziness - Slurred speech
effective in torsade de pointes and digoxin toxicity

22. In coma situations you rule out What (7)?

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23. What is the mechanism of action of Mifepristone (RU486)?
Competitive inibitor of progestins at progesterone receptors.
AluMINIMUM amount of feces.
It acts presynaptically to increase NE release.
- Disulfram & also sulfonylureas - metronidazole

24. What is the mechanism of action of Allopurinol used to treat chronic gout?
- Physostigmine salicylate
Slow - limited by half lives of clotting factors
Useful in muscle paralysis during surgery or mechanical ventilation.
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.

25. What is the MOA of Imipenem?
Acts as a wide spectrum carbapenem
Verapamil - Diltiazem - Bepridil
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic
Bacitracin - Vancomycin

26. Esmolol - short or long acting?
very short acting
Foscarnet = pyroFosphate analog
Alpha -1 antagonist
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity

27. What is are two clinical uses of Cyclosporine?
Digitoxin 70% Digoxin 20-40%
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.
When pts have Low CD4+ (< 500 cells/cubic mm) or a High Viral Load
It inhibits release of NE.

28. What are two clinical uses of Azathioprine?
In 4 half - lifes= (94%) T1/2 = (0.7x Vd)/CL
Lidocaine - Mexiletine - Tocainide
distal convoluted tubule (early)
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)

29. What are common toxicities associated with Tetracyclines?

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30. List the mechanism - clinical use - & toxicity of Nitrosureas.
- Alkalate DNA - Brain tumors - CNS toxicity
- Methylene blue
cross - allergenic
Blocks Peptide Bond formation at the 50S subunit - Bacteriostatic

31. What is a common drug interaction associated with Griseofulvin?
Increases coumadin metabolism
severe hypertension - CHF
Extended spectrum penicillin: certain Gram + bacteria and Gram - rods
Inhibit DNA Gyrase (topoisomerase II) - Bactericidal

32. List the specific antidote for this toxin: Antimuscarinic (anticholinergic)
orthostatic and exercise hypotension - sexual dysfunction - diarrhea
No - hemicholinum block the uptake of Choline and thus Ach synthesis
- Physostigmine salicylate
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome

33. Name four HMG- CoA reductase inhibitors.
Interferes with microtubule function - disrupts mitosis - inhibits growth
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.
Lovastatin - Pravastatin - Simvastatin - Atorvastatin
Cephalosporins

34. Which drug(s) cause this reaction: Cinchonism (2)?
Aminoglycosides - Tetracyclines
Inhibits CMV DNA polymerase
When pts have Low CD4+ (< 500 cells/cubic mm) or a High Viral Load
- Quinidine - quinine

35. How is Griseofulvin used clinically?
is resistant
Local anesthetic.
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.
Oral treatment of superficial infections

36. What is the memory key to remember Which pathway (extrinsic vs. intrinsic) and Which lab value Warfarin affects?
Hexamethonium is a nicotinic antagonist - and thus is a ganglionic blocker.
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.
GET on the Metro
Dopamine; causes its release from intact nerve terminals

37. How can the t1/2 of INH be altered?
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.
Modification via Acetylation - Adenylation - or Phosphorylation
Post - op and neurogenic ileus and urinary retention - myasthenia gravis - and reversal of neuromuscular junction blockade (post - op) through anticholinesterase activity.
Fast vs. Slow Acetylators

38. What enzyme is responsible for the breakdown of ACh in the synaptic cleft?
Treatment of infertility.
Acetylcholinesterase; ACh is broken down into choline and acetate.
- S- phase anti - metabolite folate analogue - Luk - Lymp - sarc - RA - & psoriasis / - Reversible myelosuppression
Penicillin.

39. What is the MOA for Acyclovir?
Pyridoxine (B6) administration
Inhibit viral DNA polymerase
Premature infants - because they lack UDP- glucuronyl transferase
Amphetamine and Ephedrine

40. Are Ampicillin and Amoxicillin are not...
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity
penicillinase resistant
Non - Nucleosides

41. What is the MOA for the Aminoglycosides?
Inhibits formation of Initiation Complex - causes misreading of mRNA - Bactericidal
Megaloblastic anemia - Leukopenia - Granulocytopenia
Inhibition of 50S peptidyl transferase - Bacteriostatic
Epinephrine to treat anaphylaxis. Also useful if you have open angle glaucoma - asthma - or hypotension.

42. How is Amantadine used clinically?

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43. What are the side effects of Rifampin?
Minor hepatotoxicity - Drug interactions (activates P450)
competitive inhibirot of aldosterone in the cortical collecting tubule
CL= (rate of elimination of drug/ Plasma drug conc.)
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity

44. Acetaldehyde is metabolized by Acetaldehyde dehydrogenase - Which drug inhibs this enzyme?
GI upset - Superinfections - Skin rashes - Headache - Dizziness
- Disulfram & also sulfonylureas - metronidazole
sedation - sleep alterations
dizziness - flushing - constipation (verapamil) - nausea

45. K+ sparing diuretics - site of action?
- Shifts the curve down - reduces Vmax
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.
vasodilator - increases cGMP to induce smooth muscle relaxation (arterioles>veins; afterload reduction)
cortical collecting tubule

46. What is a common side effect of Misoprostol?
Diarrhea
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)
Erythromycin - Azithromycin - Clarithromycin
narcolepsy - obesity - and attention deficit disorder (I wouldn't recommend this)

47. What is the memory key for Isoniazid (INH) toxicity?
- Haloperidol - chlorpromazine - reserpine - MPTP
Erythromycin - Azithromycin - Clarithromycin
propanolol - esmolol - metoprolol - atenolol - timolol
INH: Injures Neurons and Hepatocytes

48. MOA: Block protein synthesis at 30s subunit
1. Streptokinase 2. Urokinase 3. tPA (alteplase) - APSAC (anistreplase)
Aminoglycosides - Tetracyclines
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more
decrease conduction velocity - increase ERP - increase PR interval

49. Ca2+ channel blockers - mechanism?
Norepinephrine
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility
Hypersensitivity reactions
Rheumatoid and osteoarthritis.

50. List the specific antidote for this toxin: Heparin
- Halothane - Valproic acid - acetaminophen - Amantia phalloides
Acetylcholinesterase; ACh is broken down into choline and acetate.
- Protamine
- Class III antiarrhythmics (sotalol) - class IA (quinidine)