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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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1. Name two classes of drugs for HIV therapy
Protease Inhibitors and Reverse Transcriptase Inhibitors
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine
- Hydralazine - Procainamide - INH - phenytoin

2. How can the t1/2 of INH be altered?
Nucleosides
Fast vs. Slow Acetylators
Cilastatin
Ibuprofen - Naproxen - and Indomethacin

3. For Warfarin What is the Site of action
- ED 50 is less than the Km (less than 50% of receptors)
Liver
Methylzanthine; desired effect is bronchodilation - may cause bronchodilation by inhibiting phosphodiesterase - enzyme involved in degrading cAMP (controversial).
- acetylation - glucuron. - & sulfation - Conjugation - Polar product

4. MOA: Block DNA topoisomerases
Beta 2 agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Use during acute exacerbation.
increase AP duration - increase ERP - increase QT interval - for use When other arrhythmics fail
Quinolones
Rheumatoid and osteoarthritis.

5. What is the lab value used to monitor the effectiveness of Warfarin therapy?
The PT.
Inhibit RT of HIV and prevent the incorporation of viral genome into the host DNA
Interferes with microtubule function - disrupts mitosis - inhibits growth
- Upper respiratory tract infections - pneumonias - STDs: Gram+ cocci (streptococcal infect in pts allergic to penicillin) - Mycoplasma - Legionella - Chlamydia - Neisseria

6. Spironolactone - mechanism?
Chronic (weeks or months)
As an anticholinesterase it increases endogenous ACh and thus increases strength.
Pituitary hormone.
competitive inhibirot of aldosterone in the cortical collecting tubule

7. Quinidine - toxicity?
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow
Oral treatment of superficial infections

8. What are common toxicities associated with Tetracyclines?

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9. What is Imipenem always administered with?
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.
NO
When pts have Low CD4+ (< 500 cells/cubic mm) or a High Viral Load
Cilastatin

10. What is the MOA for the Macrolides?
Captopril - Enalapril - Lisinopril
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.
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic
Phosphorylation by a Viral Kinase

11. A 12yo patient was treated for a reaction to a bee sting - What drug provides the best coverage of sympathomimetic receptors?
- Clindamycin
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.
Resistant Gram - infections
Epinephirine(Alpha1 -2 and Beta 1 -2)

12. Which drug(s) cause this reaction: Hot flashes?
competitive inhibirot of aldosterone in the cortical collecting tubule
Neutropenia
Sotalol - Ibutilide - Bretylium - Amiodarone
- Tamoxifen

13. Which drug(s) cause this reaction: Neuro and Nephrotoxic?
Amphetamine and Ephedrine
- polymyxins
loop diuretics - spironolactone
- N- acetylcystine

14. Aztreonam ________ to penicillinase
is resistant
Systemic mycoses
1)Binds penicillin - binding proteins 2) Blocks transpeptidase cross - linking of cell wall 3) Activates autolytic enzymes
increase AP duration - increase ERP - increase QT interval - for use When other arrhythmics fail

15. What is the mechanism of action of Omeprazole - Lansoprazole?
local anesthetic. CNS stimulation or depression. CV depression.
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention
Irreversibly inhibits H+/K+ ATPase in stomach parietal cells.
- Estrogen receptor antagonist - Breast CA - increased endometrial CA risk

16. Which drug(s) cause this reaction: Adrenocortical Insufficiency
- Glucocorticoid withdrawal
Digitoxin 168hrs Digoxin 40 hrs
- Fluoroquinolones
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility

17. Ca2+ channel blockers - clinical use?
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.
hypertension - angina - arrhythmias
- Methylene blue
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.

18. What are the clinical indications for bethanechol?
dizziness - flushing - constipation (verapamil) - nausea
Inhibits DNA dependent RNA polymerase
Activates cholinergic receptors on bladder and bowel smooth muscle - alleviating post - op and neurogenic ileus and urinary retention.
Forms toxic metabolites in the bacterial cell - Bactericidal

19. Which antimuscarinic agents are used in producing mydriasis and cycloplegia?
atropine - homatropine - tropicamide
Cyclooxygenases (COX I - COX II).
Captopril - Enalapril - Lisinopril
1. Bleeding 2. Teratogenicity 3. Drug - drug interactions

20. What is the MOA for Acyclovir?
Inhibit viral DNA polymerase
Clavulanic acid
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.
Bleeding.

21. What is a common side effect of Colchicine used to treat acute gout - especially When given orally?
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium
Anaerobes
GI side effects. (Indomethacin is less toxic - more commonly used.)
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine

22. What is Metronidazole combined with for 'triple therapy'? Against What organism?
proximal convoluted tubule - thin descending limb - and collecting duct
competitive inhibirot of aldosterone in the cortical collecting tubule
Inhibit DNA Gyrase (topoisomerase II) - Bactericidal
Bismuth and Amoxicillin or Tetracycline; against Helobacter pylori

23. Mannitol - mechanism?
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow
Same as penicillin. Extended spectrum antibiotics
DOC in diagnosing and abolishing AV nodal arrhythmias
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.

24. What are the products and their toxicities of the metabolism of Ethylene Glycol by / alcohol dehydrogenase?
- Oxalic acid - Acidosis & nephrotoxicity
Acetylcholine esterase
Verapamil - Diltiazem - Bepridil
- Estrogen receptor antagonist - Breast CA - increased endometrial CA risk

25. Name three calcium channel blockers?
Nifedipine - Verapamil - Diltiazem
Lovastatin - Pravastatin - Simvastatin - Atorvastatin
Does not cross
Norepinephrine (Alpha1 -2 and beta 1)

26. What can result due to antacid overuse?
Can affect absorption - bioavailability - or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying.
loop diuretics - spironolactone
cross - allergenic
Rare.

27. What is a common drug interaction associated with Griseofulvin?
loop diuretics - thiazides
DOC in diagnosing and abolishing AV nodal arrhythmias
Increases coumadin metabolism
bradycardia - AV block - CHF

28. Adverse effects of Clonidine?
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis
dry mouth - sedation - severe rebound hypertension
Edrophonium
Ca2+ (Loops Lose calcium)

29. Amiodarone - toxicity?
Increases mean - systolic - and diastolic bp - while there is little change in pulse pressure.
Activates antithrombin III
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.
CL= (rate of elimination of drug/ Plasma drug conc.)

30. What are two clinical uses of Azathioprine?
Misoprostol is contraindicated in women of childbearing potential because it is an abortifacient.
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)
Fever/Chills - Hypotension - Nephrotoxicity - Arrhythmias
Well tolerated in general but occasionally - Nephrotoxicity - Ototoxicity - Thrombophlebitis - diffuse flushing='Red Man Syndrome'

31. What is the mecanism of action of the COX-2 inhibitors (celecoxib - rofecoxib)?
Megaloblastic anemia - Leukopenia - Granulocytopenia
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.
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)
Selectively inhibit cyclooxygenase (COX) isoform 2 - Which is found in inflammatory cells nad mediates inflammation and pain; spares COX-1 Which helps maintain the gastric mucosa.

32. Which drug(s) cause this reaction: Osteoporosis (2)?
1. Antipyretic 2. Analgesic 3. Anti - inflammatory
BM suppression (neutropenia - anemia) - Peripheral neuropathy
- Corticosteroids - heparin
Neomycin

33. What are the clinical indications for Azole therapy?
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs
Systemic mycoses
1.Gram - rods of the Urinary and GI tracts (including Pseudomonas) 2.Neisseria 3. Some Gram + organisms
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome

34. Where does Griseofulvin deposit?
aPTT (intrinsic pathway)
- ACE inhibitors (Losartan>no cough)
- Vinca alkaloids(inhibit MT) - Paclitaxel
Keratin containing tissues - e.g. - nails

35. List the specific antidote for this toxin: Tricyclic antidepressants
- NaHCO3
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens
- Haloperidol - chlorpromazine - reserpine - MPTP
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity

36. A common side effects of Interferon (INF) treatment is?
thick ascending limb
Neutropenia
Headache - flushing - dyspepsia - blue - green color vision.
GI disturbances.

37. What is the mechanism of action and clinical use of the antiandrogens Ketoconazole and Spironolactone?
No. Atropine is used to reduce urgency in mild cystitis. So it would aggravate the urinary retention.
Inhibit steroid synthesis - used in the treatment of polycystic ovarian syndrome to prevent hirsutism.
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids
Penicillin - V

38. Acetaminophen has What two clinical uses and lacks What one clinical use of the NSAIDs?
Dry flushed skin - due to inhibition of sympathetic post - ganglionic blockade on muscarinic receptors of sweat glands. All others are opposite of What would be expected.
physostigmine
1. Acarbose 2. Miglitol
Acetaminophen has antipyretic and analgesic properties - but lacks anti - inflammatory properties.

39. Clinical use of Isoniazid (INH)?
proximal convoluted tubule
Mycobacterium tuberculosis - the only agent used as solo prophylaxis against TB
Rapid (seconds)
Albuterol - tertbutaline

40. What musculo - skeletal side effects in Adults are associated with Floroquinolones?
Blocks Peptide Bond formation at the 50S subunit - Bacteriostatic
collecting ducts
Beta antagonist.
Tendonitis and Tendon rupture

41. Why is there a drop in systolic - mean - and diastolic bp with infusion of isoproterenol?
TCA
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
Cyclooxygenases (COX I - COX II).

42. Amprotericin B ___________ the BBB
Does not cross
Extended spectrum penicillin: certain Gram + bacteria and Gram - rods
effective in torsade de pointes and digoxin toxicity
Rheumatoid and osteoarthritis.

43. These drugs acts indirectly by releasing strored catecholamines in the presynaptic terminal
Tubocurarine - atracurium - mivacurium - pancuronium - vecuronium - rapacuronium
- Alkalate DNA - Brain tumors - CNS toxicity
Amphetamine and Ephedrine
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors

44. Hydrochlorothiazide - clinical use?
HTN - CHF - calcium stone formation - nephrogenic DI.
AZT - to reduce risk of Fetal Transmission
Anaerobes
Prevents release of mediators from mast cells. Effective only for the prophylaxis of asthma. Not effective during an acute attack.

45. List the specific antidote for this toxin: Methanol & Ethylene glycol
- Ethanol - dialysis - & fomepizole
Benzathine penicillin G
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
cardiac depression - peripheral edema - flushing - dizziness - constipation

46. Would blockade of muscarininc receptors in the bladder be useful in treating urinary retention?
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.
No. Atropine is used to reduce urgency in mild cystitis. So it would aggravate the urinary retention.
Cilastatin
dizziness - flushing - constipation (verapamil) - nausea

47. What are three possible complications of Heparin therapy?
- Ethanol - dialysis - & fomepizole
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions
Edrophonium
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow

48. Describe Phase I metabolism in liver(3)?
- reduction - oxy - & hydrolysis - H2O sol. Polar product - P450
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.
Spironolactone - Triamterene - Amiloride (the K+ STAys)
Pseudomonas species and Gram - rods

49. What is the mechanism of action of Acetaminophen?
sedation - depression - nasal stuffiness - diarrhea
Rare.
Premature infants - because they lack UDP- glucuronyl transferase
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.

50. What are four Sulfonylureas?
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium
Finasteride inhibits 5 Alpha - reductase - this decreases the conversion of testosterone to dihydrotestosterone - useful in BPH
Leukotrienes increasing bronchial tone.
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide