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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. Adverse effects of Hydrochlorothiazide?
Peptic ulcer disease.
No - it inhibits the release of Nor Epi
- Corticosteroids - heparin
hypokalemia - slight hyperlipidemia - hyperuricemia - lassitude - hypercalcemia - hyperglycemia

2. Procainamide - toxicity?
Atropine pts are suffering from Cholinestrase inhibitor poisining (Nerve gas/Organophosphate poisining)
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis
Acts as a wide spectrum carbapenem
reversible SLE- like syndrome

3. Antiarrhythmic class IV- effects?
cardiac muscle: Verapamil>Diltiazem>Nifedipine
1. Buffalo hump 2. Moon facies 3. Truncal obesity 4. Muscle wasting 5. Thin skin 6. Easy bruisability 7. Osteoporosis 8. Adrenocortical atrophy 9. Peptic ulcers
decrease conduction velocity - increase ERP - increase PR interval
all except the K+ sparing diuretics Spironolactone - Triamterene - Amiloride

4. Which drug(s) cause this reaction: Stevens - Johnson syn. (3)?
Aluminum sucrose sulfate polymerizes in the acid environment of the stomach and selectively binds necrotic peptic ulcer tissue. Acts as a barrier to acid - pepsin - and bile.
Chronic anticoagulation.
- Ethosuxamide - sulfonamides - lamotrigine
Pralidoxime regenerates active cholinesterase.

5. List the specific antidote for this toxin: Amphetamine
Na/K ATPase
Vibrio cholerae Acne Chlamydia Ureaplasma Urealyticum Mycoplasma pneumoniae Borrelia burgdorferi (Lyme's) Rickettsia Tularemia
- Ammonium Chloride
thick ascending limb

6. List the specific antidote for this toxin: Benzodiazepines
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
- Flumazenil
loop diuretics - thiazides
Sotalol - Ibutilide - Bretylium - Amiodarone

7. For Heparin What is the Structure
Large anionic polymer - acidic
Hypokalemic metabolic alkalosis - hyponatremia - hyperGlycemia - hyperLipidemia - hyperUricemia - hyperCalcemia - sulfa allergy.
INH: Injures Neurons and Hepatocytes
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time

8. What is the mechanism of action of the glucocorticoids?
Albuterol - tertbutaline
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.
- Airway - Breathing - Circulation - Dextrose (thiamine & narcan) - ABCD
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.

9. What is the category of drug names ending in - azepam (e.g. Diazepam)
Tetracycline - Doxycycline - Demeclocycline - Minocycline
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time
Modification via Acetylation
Benzodiazepine.

10. Digoxin v. Digitoxin: bioavailability?
Digitoxin>95% Digoxin 75%
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol
- Fluoroquinolones
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents

11. What is an acronym to remember Anti - TB drugs?
Succinylcholine
RESPIre
first dose orthostatic hypotension - dizziness - headache
Tricyclic antidepressant.

12. Adverse effects of Prazosin?
Receptors = D1=D2>beta>alpha - thus increasing heart rate (beta) and blood pressure (alpha vasoconstriction) while maintaining kidney perfusion (dopamine receptors)
physostigmine
first dose orthostatic hypotension - dizziness - headache
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide

13. What is the memory aid for subunit distribution of ribosomal inhibitors?

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14. What is the receptor affinity and clinical use of isoproterenol?
It affects beta receptors equally and is used in AV heart block (rare).
severe orthostatic hypotension - blurred vision - constipation - sexual dysfunction
Triple sulfas or SMZ
Well tolerated in general but occasionally - Nephrotoxicity - Ototoxicity - Thrombophlebitis - diffuse flushing='Red Man Syndrome'

15. List the specific antidote for this toxin: Opioids
propanolol - esmolol - metoprolol - atenolol - timolol
block Na+ channels in the cortical collecting tubule
loop diuretics - thiazides
- B51Naloxone / naltrexone (Narcan)

16. Which RT inhibitors cause Lactic Acidosis?
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow
Nucleosides
Finasteride inhibits 5 Alpha - reductase - this decreases the conversion of testosterone to dihydrotestosterone - useful in BPH
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide

17. Which drug(s) cause this reaction: Focal to massive hepatic necrosis (4)?
proarrhythmic
- Halothane - Valproic acid - acetaminophen - Amantia phalloides
- Alkalinize urine & dialysis
Mebendazole/Thiabendazole - Pyrantel Pamoate

18. What are the clinical uses for Ticlopidine - Clopidogrel?
Rifampin
1. Skin rash 2. Agranulocytosis (rare) 3. Aplastic anemia
Ciprofloxacin - Norfloxacin - Ofloxacin - Grepafloxacin - Enoxacin - Nalidixic acid
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.

19. What is the mechanism of Azathioprine?
Inhibits reabsorption of uric acid.
Tendonitis and Tendon rupture
1. Bleeding 2. Teratogenicity 3. Drug - drug interactions
Antimetabolite derivative of 6- mercaptopurine that interferes with the metablolism and synthesis of nucleic acid.

20. Name four HMG- CoA reductase inhibitors.
Lovastatin - Pravastatin - Simvastatin - Atorvastatin
Rash - Pseudomembranous colitis
Onchocerciasis ('river blindness'-- rIVER- mectin)
Neutropenia

21. Which antimicrobial classes inhibit protein synthesis at the 30S subunit? (2)
Verapamil - Diltiazem - Bepridil
- Shifts the curve down - reduces Vmax
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic

22. What microorganisms is Aztreonam not effective against?
Decreases synthesis of Mycolic Acid
local anesthetic. CNS stimulation or depression. CV depression.
Gram + and Anerobes
No - warfarin - unlike heparin - can cross the placenta.

23. What is the MOA of Ganciclovir?
Lovastatin - Pravastatin - Simvastatin - Atorvastatin
- Chlorpromazine - thioridazine - haloperidol
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.
Inhibits CMV DNA polymerase

24. MOA: Block DNA topoisomerases
Keratin containing tissues - e.g. - nails
Chronic gout.
Quinolones
Chronic gout.

25. Triamterene and amiloride - mechanism?
cholestyramine - colestipol
- Phase I (clinical tests) - Phase II - Phase III - PhaseIV (surveillance)
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis
block Na+ channels in the cortical collecting tubule

26. For Warfarin What is the Site of action
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time
severe orthostatic hypotension - blurred vision - constipation - sexual dysfunction
Liver
Protamine sulfate

27. What are two toxicities associated with Cyclosporine?
1. Predisposes to viral infections and lymphoma 2. Nephrotoxic (preventable with mannitol diuresis)
- Methylene blue
Neutropenia (ticlopidine); reserved for those who cannot tolerate aspirin.
These B-2 agonists cause respiratory smooth muscle to relax.

28. What is the category - method of use - and adverse effects of Salmeterol in Asthma treatment?
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.
Zidovudine (AZT) - Didanosine (ddI) - Zalcitabine (ddC) - Stavudine (d4T) - Lamivudine (3TC)
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.
- Steroids - Tamoxifen

29. Cocaine shares is mechanism of action with What antidepressant
TCA
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain
proximal convoluted tubule - thin descending limb - and collecting duct
Those patients who are taking nitrates.

30. Can Heparin be used during pregnancy?
Clomiphene is a partial agonist at estrogen receptors in the pituitary gland. Prevents normal feedback inhibition and increses release of LH and FSHfrom the pituitary - Which stimulates ovulation.
Yes - it does not cross the placenta.
Botulinum
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels

31. Ca2+ channel blockers - site of action?
Cell membrane Ca2+ channels of cardiac sarcomere
cortical collecting tubule
Minor hepatotoxicity - Drug interactions (activates P450)
Protamine Sulfate is used for rapid reversal of heparinization (positively charged molecule that binds to negatively charged heparin).

32. How does resistance to Vancomycin occur?
No
- Shifts the curve down - reduces Vmax
With an amino acid change of D- ala D- ala to D- ala D- lac
depresses ectopic pacemakers - especially in digoxin toxicity

33. Thiazides - site of action?
dry mouth - sedation - severe rebound hypertension
distal convoluted tubule (early)
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
Beta1 more than B2

34. What is the clincial use for Misoprostol?
Mycobacterium tuberculosis - the only agent used as solo prophylaxis against TB
Prevention of NSAID- induced peptic ulcers - maintains a PDA.
- Hypersensitivity reactions - Hemolysis - Nephrotoxicity (tubulointerstitial nephritis) - Kernicterus in infants Displace other drugs from albumin (e.g. - warfarin)
impotence - exacerbation of asthma - CV effects - CNS effects - may mask hypoclycemia

35. Which drug(s) cause this reaction: Diabetes insipidus?
Phase 1 = prolonged depolarization - no antidote - effect potentiated by anticholinesterase; Phase 2 = repolarized but blocked - an anticholinesterase is the antidote for this phase.
- Cloazapine - carbamazapine - colchicine - PTU
- Lithium
INH: Injures Neurons and Hepatocytes

36. Which H2 Blocker has the most toxic effects and What are they?
Abortifacient.
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.
Same as penicillin. Extended spectrum antibiotics
competitive inhibirot of aldosterone in the cortical collecting tubule

37. What is the category - mechanism of action - and particular use of beclomethasone and prednisone in Asthma treatment?
Used in combination therapy with SMZ to sequentially block folate synthesis
check PFTs - LFTs - and TFTs
blocking the beta adrenergic receptor leads to decreased cAMP - and decreased Ca2+ flux
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.)

38. Verapamil has similar action to?
Captopril - Enalapril - Lisinopril
Beta Blockers
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine
Pseudomembranous colitis (C. difficile) - fever - diarrhea

39. What are four clinical uses of glucocorticoids?

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40. What is the MOA of Amantadine?
Blocks viral penetration/uncoating; may act to buffer the pH of the endosome
Decreases synthesis of Mycolic Acid
Inhibits reabsorption of uric acid.
Beta - lactam antibiotics

41. What is Metronidazole combined with for 'triple therapy'? Against What organism?
scopolamine
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow
- Methylene blue
Bismuth and Amoxicillin or Tetracycline; against Helobacter pylori

42. How is Amphotericin B administered for fungal meningitis?
aPTT (intrinsic pathway)
Chagas' disease - American Trypanosomiasis (Trypanosoma cruzi)
Intrathecally
- DNA intercalator - Hodgkin's - myeloma - sarcoma - and solid tumors - Cardiotoxicity & alopecia

43. Spironolactone - mechanism?
Increased systolic and pulse pressure - decreased diastolic pressure - and little change in mean pressure.
competitive inhibirot of aldosterone in the cortical collecting tubule
Prevents the release of calcium from the sarcoplasmic reticulum of skeletal muscle.
Digitoxin 70% Digoxin 20-40%

44. What are the major structural differences between Penicillin and Cephalosporin?
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)
Gram + and Anerobes
Potent immunosuppressive used in organ transplant recipients.
Imipenem

45. Antiarrhythmic class II- toxicity?
impotence - exacerbation of asthma - CV effects - CNS effects - may mask hypoclycemia
prevention of nodal arrhythmias (SVT)
Minor hepatotoxicity - Drug interactions (activates P450)
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time

46. Hydralazine - class and mechanism?
Doxycycline - because it is fecally eliminated
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.
H2 antagonist
vasodilator - increases cGMP to induce smooth muscle relaxation (arterioles>veins; afterload reduction)

47. What is the memory key for Metronidazole's clinical uses?
AluMINIMUM amount of feces.
No - hemicholinum block the uptake of Choline and thus Ach synthesis
GET on the Metro
Antifungal.

48. Which drug(s) cause this reaction: Tubulointerstitial Nephritis (5)?
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)
Binds to cyclophilins (peptidyl proline cis - trans isomerase) - blocking the differentiation and activation of T cells mainly by inhibiting the production of IL-2 and its receptor.
edrophonium (extremely short acting anticholinesterase)
Blocking muscarinic receptors in the circular fibers of the eye - results in unopposed action of radial muscles to dilate.

49. What is the difference in receptor affinity of epinephrine at low doses? High doses?

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50. What is the MOA of Ribavirin?
- Bleomycin - amiodarone - busulfan
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis
- Act on same receptor - Full has greater efficacy
Verapamil - Diltiazem - Bepridil