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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. Digoxin v. Digitoxin: bioavailability?
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic
Epinephrine to treat anaphylaxis. Also useful if you have open angle glaucoma - asthma - or hypotension.
Digitoxin>95% Digoxin 75%
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval

2. Which antimuscarinic agents are used in producing mydriasis and cycloplegia?
atropine - homatropine - tropicamide
Systemic mycoses
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.
Extended spectrum penicillin: certain Gram + bacteria and Gram - rods

3. What enzyme is responsible for the degredation of Ach
Diarrhea - Urination - Miosis - Bronchospasm - Bradycardia - Excitation of skeletal muscle and CNS - Lacrimation - Sweating - and Salivation = DUMBBELS; also abdominal cramping
NO
As an anticholinesterase it increases endogenous ACh and thus increases strength.
Acetylcholine esterase

4. MOA: Block mRNA synthesis
Modification via Acetylation - Adenylation - or Phosphorylation
fetal renal toxicity - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
Rifampin
- Class III antiarrhythmics (sotalol) - class IA (quinidine)

5. How does Ganciclovir's toxicity relate to that of Acyclovir?
Gram + - Gram - - Norcardia - Chlamydia
1. Addison's disease 2. Inflammation 3. Immune suppression 4. Asthma
Headache - flushing - dyspepsia - blue - green color vision.
Ganciclovir is more toxic to host enzymes

6. MOA for Penicillin (3 answers)?
1)Binds penicillin - binding proteins 2) Blocks transpeptidase cross - linking of cell wall 3) Activates autolytic enzymes
Digitoxin 70% Digoxin 20-40%
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity
hypertension - angina - arrhythmias

7. Hydralazine - class and mechanism?
Erectile dysfunction.
DHPG (dihydroxy-2- propoxymethyl guanine)
- Shifts the curve down - reduces Vmax
vasodilator - increases cGMP to induce smooth muscle relaxation (arterioles>veins; afterload reduction)

8. What are four H2 Blockers?
Blocks Influenza A and RubellA; causes problems with the cerebellA
Treatment of hypertension - especially with renal disease (lowers bp centrally - so flow is maintained to kidney).
Dobutamine has more of an affintiy for beta -1 than beta -2 - and is used for treating heart failure and shock. Albuterol and terbutaline is the reverse - and is used in treatment of acute asthma.
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine

9. What physiological effects was the Anes using Atropine to tx
edrophonium (extremely short acting anticholinesterase)
Meningitis (H. influenza - N. meningitidis - S. pneumoniae) - Conserative treatment due to toxicities
1. Hypoglycemia (more common with 2nd - generation drugs: glyburide - glipizide) 2. Disulfiram - like effects (not seen with 2nd - generation drugs).
SLUD (salivation - Lacrimation - urination - Defecation)as well as airway secretion - GI motility - acid secretions

10. Antiarrhythmic class II- mechanism?
GI distress - Skin rash - and Seizures at high plasma levels
Gemfibrozil - Clofibrate
blocking the beta adrenergic receptor leads to decreased cAMP - and decreased Ca2+ flux
cortical collecting tubule

11. Which diuretics decrease urine Ca2+?
thiazides - amiloride
GI distress - Tooth discoloration and Inhibition of bone growth in children - Fanconi's syndrome - Photosensitivity
Short.
Beta adrenergic receptors and Ca2+ channels (stimulatory)

12. What is treated with Chloroquine - Quinine - Mefloquine?
Benzodiazepine.
Malaria (P. falciparum)
- Clindamycin
loop diuretics - spironolactone

13. Can Warfarin be used during pregnancy?
sedation - positive Coombs' test
Hypersensitivity reactions
No - warfarin - unlike heparin - can cross the placenta.
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine

14. How is Ganciclovir used clinically?
Ataxia - Dizziness - Slurred speech
When pts have Low CD4+ (< 500 cells/cubic mm) or a High Viral Load
CMV - esp in Immunocompromised patients
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.

15. List the specific antidote for this toxin: Anticholinesterases (organophosphate.)
The only local anesthetic with vasoconstrictive properties.
hyperaldosteronism - K+ depletion - CHF
- Clindamycin
- Atropine & pralidoxime

16. What is the MOA for Metronidazole?
Penicillin.
Forms toxic metabolites in the bacterial cell - Bactericidal
Increases coumadin metabolism
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.

17. Clonidine is the preferred sym pathomimetic tx of HTN in pts with renal disease - why??
Scopolamine
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow
GI upset
Saquinavir - Ritonavir - Indinavir - Nelfinavir

18. Ca2+ channel blockers - site of action?
Sulfonamides - Trimethoprim
Inhibits cell wall mucopeptide formation - Bactericidal
Cell membrane Ca2+ channels of cardiac sarcomere
- Physostigmine salicylate

19. Name the steps in drug approval(4)?
- Phase I (clinical tests) - Phase II - Phase III - PhaseIV (surveillance)
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
Does not cross
INH: Injures Neurons and Hepatocytes

20. Name two classes of drugs for HIV therapy
Protease Inhibitors and Reverse Transcriptase Inhibitors
- Vitamin K & fresh frozen plasma
Lipoxygenase
Oxygen

21. Which Aminoglycoside is used for Bowel Surgery ?
Fluconazole - Ketoconazole - Clotrimazole - Miconazole - Itraconazole
Modification via Acetylation - Adenylation - or Phosphorylation
- Niacin - Ca++ channel blockers - adenosine - vancomycin
Neomycin

22. What is the category and mechanism of action of Zafirlukast in Asthma treatment?
impotence - exacerbation of asthma - CV effects - CNS effects - may mask hypoclycemia
not a sulfonamide - but action is the same as furosemide
Antileukotriene; blocks leukotriene receptors.
Diarrhea

23. Are penicillinase resistant
Digitoxin 70% Digoxin 20-40%
1. Antipyretic 2. Analgesic 3. Anti - inflammatory 4. Antiplatelet drug.
Captopril - Enalapril - Lisinopril
Methicillin - Nafcillin - and Dicloxacillin

24. A 12yo patient was treated for a reaction to a bee sting - What drug provides the best coverage of sympathomimetic receptors?
Epinephirine(Alpha1 -2 and Beta 1 -2)
loop diuretics - spironolactone
all except the K+ sparing diuretics Spironolactone - Triamterene - Amiloride
Does not cross

25. Which drug(s) cause this reaction: Gynecomastia (6)?
hyperchloremic metabolic acidosis - neuropathy - NH3 toxicity - sulfa allergy
Sotalol - Ibutilide - Bretylium - Amiodarone
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens
pulmonary edema - dehydration

26. What is the chemical name for Ganciclovir?
DHPG (dihydroxy-2- propoxymethyl guanine)
Receptors = D1=D2>beta>alpha - thus increasing heart rate (beta) and blood pressure (alpha vasoconstriction) while maintaining kidney perfusion (dopamine receptors)
Peptic ulcer disease.
local anesthetic. CNS stimulation or depression. CV depression.

27. Why are the Sulfonylureas inactive in IDDM (type -1)?
Protease inhibitor.
torsade de pointes - excessive Beta block
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic
Because they require some residual islet function.

28. List the mechanism - clinical use - & toxicity of Busulfan.
Peptic ulcer disease.
- Alkalates DNA - CML - Pulmonary fibrosis hyperpigmentation
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.
glaucoma - urinary alkalinization - metabolic alkalosis - altitude sickness

29. What is the mechanism of Tacrolimus (FK506)?
Similar to cyclosporine; binds to FK- binding protein - inhibiting secretion of IL-2 and other cytokines.
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.
- Glucagon
Inhibits DNA dependent RNA polymerase

30. In What population does Gray Baby Syndrome occur? Why?
Premature infants - because they lack UDP- glucuronyl transferase
Oral treatment of superficial infections
hyperchloremic metabolic acidosis - neuropathy - NH3 toxicity - sulfa allergy
- polymyxins

31. List the specific antidote for this toxin: Cyanide
- Haloperidol - chlorpromazine - reserpine - MPTP
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)
- Nitrate - hydroxocobalamin thiosulfate
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)

32. ADH antagonists - site of action?
- Disulfram & also sulfonylureas - metronidazole
GET on the Metro
- Alkalating agent - testicular - bladder - ovary -& lung - Nephrotoxicity & CN VIII damage.
collecting ducts

33. Furosemide - class and mechanism?
Heparin catalyzes the activation of antithrombin III.
Sucralfate cannot work in the presence of antacids or H2 blockers because it requires an acidic environment to polymerize.
first dose orthostatic hypotension - dizziness - headache
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.

34. Which drug(s) cause this reaction: Drug induced Parkinson's (4) ?
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.
Inhibit steroid synthesis - used in the treatment of polycystic ovarian syndrome to prevent hirsutism.
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased
- Haloperidol - chlorpromazine - reserpine - MPTP

35. Toxic effects of TMP include?
Megaloblastic anemia - Leukopenia - Granulocytopenia
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.
Oral
- Chloramphenicol

36. How would hemicholinium treatment affect cholinergic neurons?
Keratin containing tissues - e.g. - nails
cardiac depression - peripheral edema - flushing - dizziness - constipation
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.
Hemicholinium inhibits the transport of choline into the nerve - thus inhibiting formation of ACh.

37. What is the receptor affinity and clinical use of isoproterenol?
Scopolamine
prevention of nodal arrhythmias (SVT)
Neurotoxicity - Acute renal tubular necrosis
It affects beta receptors equally and is used in AV heart block (rare).

38. Resistance mechanisms for Sulfonamides
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis
anticholinesterase glaucoma
hyperchloremic metabolic acidosis - neuropathy - NH3 toxicity - sulfa allergy
Acetaminophen has antipyretic and analgesic properties - but lacks anti - inflammatory properties.

39. Which antimicrobial classes inhibit protein synthesis at the 30S subunit? (2)
very short acting
- Clindamycin
check PFTs - LFTs - and TFTs
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic

40. What is the memory key to remember Which pathway (extrinsic vs. intrinsic) and Which lab value Warfarin affects?
Hormone synthesis inhibition (Gynecomastia) - Liver dysfunction (Inhibits CYP450) - Fever - Chills
Prevents release of mediators from mast cells. Effective only for the prophylaxis of asthma. Not effective during an acute attack.
Indomethacin is used to close a patent ductus arteriosus.
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.

41. What is a mnemonic to remember Amantadine's function?
Blocks Influenza A and RubellA; causes problems with the cerebellA
Protease inhibitor.
Phenothiazine (neuroleptic - antiemetic).
- Methylene blue

42. Ethacrynic Acid - toxicity?
1. Acarbose 2. Miglitol
Heparin catalyzes the activation of antithrombin III.
Giardiasis - Amoebic dysentery (E. histolytica) - Bacterial vaginitis (Gardnerella vaginalis) - Trichomonas
NO HYPERURICEMIA - NO SULFA AllERGY; same as furosemide otherwise

43. Why is reserpine effective in treating HTN?
AV nodal cells
Rare.
Reserpine inhibits dopamine transport into vesicles - attenuating its conversion to NE by dopamine beta - hydroxylase.
Prevents the release of ACh - Which results in muscle paralysis.

44. What is combination TMP- SMZ used to treat?
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs
Antileukotriene; blocks synthesis by lipoxygenase.
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia
anticholinesterase glaucoma

45. Furosemide - clinical use?
1. In liver - increases storage of glucose as glycogen. 2. In muscle - stimulates glycogen and protein synthesis - and K+ uptake. 3. In adipose tissue - facilitates triglyceride storage.
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.
Dopamine
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia

46. What are Fluoroquinolones indicated for? (3)
Rheumatoid and osteoarthritis.
1.Gram - rods of the Urinary and GI tracts (including Pseudomonas) 2.Neisseria 3. Some Gram + organisms
NO HYPERURICEMIA - NO SULFA AllERGY; same as furosemide otherwise
Early myocardial infarction.

47. How would you reverse the effect of a neuromuscular blocking agent?
Interferes with microtubule function - disrupts mitosis - inhibits growth
Give an antichloinesterase - neostigmine - edrophonium - etc
Hemicholinium inhibits the transport of choline into the nerve - thus inhibiting formation of ACh.
Pseudomonas species and Gram - rods

48. Preferential action of the Ca2+ channel blockers at vascular smooth muscle?
new arrhythmias - hypotension
Prefers beta's at low doses - but at higher doses alpha agonist effects are predominantly seen.
vascular sm. Mus.: Nifedipine>Diltiazem>Verapamil
all of them

49. Name four HMG- CoA reductase inhibitors.
Intrathecally
Due to the presence of a bulkier R group
Lovastatin - Pravastatin - Simvastatin - Atorvastatin
Methylation of rRNA near Erythromycin's ribosome binding site

50. What are three clinical uses of the NSAIDs?
1. Antipyretic 2. Analgesic 3. Anti - inflammatory
Gram + and Anerobes
Diuresis in pateints with sulfa allergy
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)