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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.
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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. Which cancer drugs work at the level of proteins(2)?
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.
- Vinca alkaloids(inhibit MT) - Paclitaxel
Triple sulfas or SMZ
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.

2. Resistance mechanisms for Macrolides

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3. Resistance mechanisms for Cephalosporins/Penicillins
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention
Tricyclic antidepressant.
Beta - lactamase cleavage of Beta - lactam ring
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval

4. What is the clinical use for Sildenafil (Viagra)?
orthostatic and exercise hypotension - sexual dysfunction - diarrhea
1. Better bioavailability 2. 2 to 4 times longer half life 3. Can be administered subcutaneously 4. Does not require laboratory monitoring
Erectile dysfunction.
G6PD deficient individuals

5. What is the mechanism of action of NSAIDs other than Aspirin?
Lidocaine - Mexiletine - Tocainide
is resistant
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.
Short.

6. List the specific antidote for this toxin: Heparin
Pralidoxime regenerates active cholinesterase.
- Alkalate DNA - Brain tumors - CNS toxicity
- Protamine
Mycobacterium tuberculosis - the only agent used as solo prophylaxis against TB

7. Mannitol - toxicity?
pulmonary edema - dehydration
constipation - flushing - edema - CV effects (CHF - AV block - sinus node depression) - and torsade de pointes (Bepridil)
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents
Headache - flushing - dyspepsia - blue - green color vision.

8. Furosemide - toxicity? (OH DANG)
Similar to cyclosporine; binds to FK- binding protein - inhibiting secretion of IL-2 and other cytokines.
With an amino acid change of D- ala D- ala to D- ala D- lac
sedation - positive Coombs' test
Ototoxicity - Hypokalemia - Dehydration - Allergy (sulfa) - Nephritis (interstitial) - Gout

9. Digoxin v. Digitoxin: protein binding?
Protamine sulfate
For serious - Gram + multidrug - resistant organisms
Nephrotoxicity (esp. with Cephalosporins) - Ototoxicity (esp. with Loop Diuretics)
Digitoxin 70% Digoxin 20-40%

10. Which drug(s) cause this reaction: Torsade de pointes (2)?
Epinephrine
- Class III antiarrhythmics (sotalol) - class IA (quinidine)
The PT.
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents

11. Which drug(s) cause this reaction: Fanconi's syndrome?
1. Gastric ulceration 2. Bleeding 3. Hyperventilation 4. Reye's syndrome 5. Tinnitus (CN VIII)
- Tetracycline
is resistant
Methylzanthine; desired effect is bronchodilation - may cause bronchodilation by inhibiting phosphodiesterase - enzyme involved in degrading cAMP (controversial).

12. For Heparin What is the Structure
- Cimetidine - ketoconazole - grapefruit juice - erythromycin - INH - sulfonamides
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.
Large anionic polymer - acidic
Ciprofloxacin - Norfloxacin - Ofloxacin - Grepafloxacin - Enoxacin - Nalidixic acid

13. What is the category and mechanism of action of Zafirlukast in Asthma treatment?
Bleeding.
Antileukotriene; blocks leukotriene receptors.
- acetylation - glucuron. - & sulfation - Conjugation - Polar product
Chronic anticoagulation.

14. Which drug(s) cause this reaction: Hepatitis?
- Isoniazid
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
Penicillin - V

15. What is the major toxic side effect of Penicillin?
dry mouth - sedation - severe rebound hypertension
Hypersensitivity reactions
- Shifts the curve down - reduces Vmax
block Na+ channels in the cortical collecting tubule

16. What is the mechanism of action of Colchicine used to treat acute gout?
Cephalosporins
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time
When pts have Low CD4+ (< 500 cells/cubic mm) or a High Viral Load
Depolymerizes microtubules - impairing leukocyte chemotaxis and degranulation.

17. Which drug(s) cause this reaction: Gingival hyperplasia?
- Phenytoin
cortical collecting tubule
Decreases synthesis of Mycolic Acid
Phosphorylation by a Viral Kinase

18. What are two clinical uses of Azathioprine?
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)
Acute gout.
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.
Reversible block of histamine H2 receptors

19. Side effects of Isoniazid (INH)?
Megaloblastic anemia - Leukopenia - Granulocytopenia
Beta lactams - inhibit cell wall synthesis - Bactericidal
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome
Gemfibrozil - Clofibrate

20. These drugs acts indirectly by releasing strored catecholamines in the presynaptic terminal
Beta -2 agonist.
Amphetamine and Ephedrine
Well tolerated in general but occasionally - Nephrotoxicity - Ototoxicity - Thrombophlebitis - diffuse flushing='Red Man Syndrome'
RESPIre

21. How is Amphotericin B administered for fungal meningitis?
Intrathecally
Chronic gout.
Chronic anticoagulation.
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.

22. Ethacrynic Acid - mechanism?
Erythromycin - Azithromycin - Clarithromycin
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis
Chagas' disease - American Trypanosomiasis (Trypanosoma cruzi)
not a sulfonamide - but action is the same as furosemide

23. What is the MOA for Carbenicillin - Piperacillin - and Ticarcillin?
- Steroids - Tamoxifen
Same as penicillin. Extended spectrum antibiotics
- Tricyclic antidepressants
- Aminocaproic acid

24. Ryanodine - site of action?
Gram + cocci - Proteus mirabilis - E. coli - Klebsiella pneumoniae (PEcK)
blocks SR Ca2+ channels
Rapid (seconds)
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time

25. What is the category - desired effect - and possible mechanism of Theophylline in treating Asthma?
Babiturate.
Cryptococcal meningitis in AIDS patients and Candidal infections of all types
Methylzanthine; desired effect is bronchodilation - may cause bronchodilation by inhibiting phosphodiesterase - enzyme involved in degrading cAMP (controversial).
Delirium - Tremor - Nephrotoxicity

26. ________ ae not resistant to penicillinase - - but they are less susceptible than the other Beta lactams
Verapamil - Diltiazem - Bepridil
Digitoxin 168hrs Digoxin 40 hrs
Oxygen
Cephalosporins

27. In What population does Gray Baby Syndrome occur? Why?
Digitoxin>95% Digoxin 75%
Epinephrine
Modification via Acetylation - Adenylation - or Phosphorylation
Premature infants - because they lack UDP- glucuronyl transferase

28. What type of neurological blockade would hexamethonium create?
Blood
Give an antichloinesterase - neostigmine - edrophonium - etc
Increase target cell response to insulin.
Hexamethonium is a nicotinic antagonist - and thus is a ganglionic blocker.

29. What are common toxic side effects of Sulfonamides? (5)
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility
decrease AP duration - affects ischemic or depolarized Purkinje and ventricular system
- Hypersensitivity reactions - Hemolysis - Nephrotoxicity (tubulointerstitial nephritis) - Kernicterus in infants Displace other drugs from albumin (e.g. - warfarin)
Carbenicillin - Piperacillin - and Ticarcillin

30. When is Rifampin not used in combination with other drugs?
Amphotericin B - Nystatin - Fluconazole/azoles
Scopolamine
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.
1. Meningococcal carrier state 2. Chemoprophylaxis in contacts of children with H. influenzae type B

31. What is the chemical name for Ganciclovir?
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels
Phosphorylation by a Viral Kinase
DHPG (dihydroxy-2- propoxymethyl guanine)
Increase target cell response to insulin.

32. How is Ribavirin used clinically?
for RSV
Beta - lactamase cleavage of Beta - lactam ring
- Airway - Breathing - Circulation - Dextrose (thiamine & narcan) - ABCD
Pralidoxime regenerates active cholinesterase.

33. List the specific antidote for this toxin: Methemoglobin
Saquinavir - Ritonavir - Indinavir - Nelfinavir
- Isoniazid
- Tetracycline - amiodarone - sulfonamides
- Methylene blue

34. Which drug(s) cause this reaction: Cinchonism (2)?
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.
1. Reliable (<1% failure) 2. Lowers risk of endometrial and ovarian cancer 3. Decreased incidence of ectopic pregnancy 4. Lower risk of pelvic infections 5. Regulation of menses
Digitoxin 70% Digoxin 20-40%
- Quinidine - quinine

35. What is the clinical utility of clonidine?
competitive inhibirot of aldosterone in the cortical collecting tubule
Treatment of hypertension - especially with renal disease (lowers bp centrally - so flow is maintained to kidney).
proximal convoluted tubule - thin descending limb - and collecting duct
- Glucagon

36. For Warfarin What is the Treatment for overdose
- Metronidazole - certain cephalosporins - procarbazine - sulfonylureas
IV vitamin K and fresh frozen plasma
- Quinidine - quinine
Inhibit Ergosterol synthesis

37. Name three Antiarrhythmic drugs in class IV.
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone
Aplastic anemia (dose independent) - Gray Baby Syndrome
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis
Verapamil - Diltiazem - Bepridil

38. Mannitol - mechanism?
Inhibition of 50S peptidyl transferase - Bacteriostatic
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow
ACIDazolamide' causes acidosis
Aminoglycosides - Tetracyclines

39. Antiarrhythmic class II- effects?
Indirect agonist - uptake inhibitor
- Phenytoin
Succinylcholine
decrease the slope of phase 4 - increase PR interval (the AV node is particularly sensitive)

40. Which Aminoglycoside is used for Bowel Surgery ?
Neomycin
Pentamidine
- Ethosuxamide - sulfonamides - lamotrigine
Pseudomembranous colitis (C. difficile) - fever - diarrhea

41. Resistance mechanisms for Tetracycline
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis
Decreased uptake or Increased transport out of cell
Malaria (P. falciparum)
Beta - lactamase cleavage of Beta - lactam ring

42. What is an acronym to remember Anti - TB drugs?
RESPIre
- Phase I (clinical tests) - Phase II - Phase III - PhaseIV (surveillance)
Reserpine inhibits dopamine transport into vesicles - attenuating its conversion to NE by dopamine beta - hydroxylase.
Giardiasis - Amoebic dysentery (E. histolytica) - Bacterial vaginitis (Gardnerella vaginalis) - Trichomonas

43. Which drug(s) cause this reaction: Diabetes insipidus?
Similar to cyclosporine; binds to FK- binding protein - inhibiting secretion of IL-2 and other cytokines.
- Lithium
Binds to the Pyrophosphate Binding Site of the enzyme
Ca2+ (Loops Lose calcium)

44. How does dantrolene work?
- Antipsychotics
Beta1 more than B2
carbonic anhydrase inhibitors - K+ sparing diuretics
Prevents the release of calcium from the sarcoplasmic reticulum of skeletal muscle.

45. List the specific antidote for this toxin: Digitalis
TMP- SMZ
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents
- Normalize K+ - Lidocaine - & Anti - dig Mab
Pituitary hormone.

46. What are common toxicities related to Vancomycin therapy?

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47. What is the MOA for Acyclovir?
Inhibit viral DNA polymerase
1. Pioglitazone 2. Rosiglitazone.
Rash - Pseudomembranous colitis
impotence - exacerbation of asthma - CV effects - CNS effects - may mask hypoclycemia

48. What are two Alpha - glucosidase inhibitors?
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic
1. Acarbose 2. Miglitol
- Cloazapine - carbamazapine - colchicine - PTU
decrease conduction velocity - increase ERP - increase PR interval

49. How is Vancomycin used clinically?
Phosphorylation by a Viral Kinase
1. Pioglitazone 2. Rosiglitazone.
For serious - Gram + multidrug - resistant organisms
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)

50. For Warfarin What is the Onset of action
Slow - limited by half lives of clotting factors
Increased systolic and pulse pressure - decreased diastolic pressure - and little change in mean pressure.
As an anticholinesterase it increases endogenous ACh and thus increases strength.
Paranteral (IV - SC)