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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. What is the clinical use for Nystatin?
NO HYPERURICEMIA - NO SULFA AllERGY; same as furosemide otherwise
Headache - flushing - dyspepsia - blue - green color vision.
Topical and Oral - for Oral Candidiasis (Thrush)
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.

2. In What population does Gray Baby Syndrome occur? Why?
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
Methylxanthine.
propanolol - esmolol - metoprolol - atenolol - timolol
Premature infants - because they lack UDP- glucuronyl transferase

3. Describe first - order kinetics?
Constant FRACTION eliminated per unit time.(exponential)
Inhibits CMV DNA polymerase
Mycobacterium tuberculosis - the only agent used as solo prophylaxis against TB
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.

4. What is the mechanism of action of Acetaminophen?
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.
- Steroids - Tamoxifen
Bismuth and Amoxicillin or Tetracycline; against Helobacter pylori
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

5. What is the formula for Volume of distribution (Vd)
penicillinase resistant
Vd= (Amt. of drug in body/ Plasma drug conc.)
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention
Staphlococcus aureus and Clostridium difficile (pseudomembranous colitis)

6. Decrease Digoxin dose in renal failure?
YES
Interferes with microtubule function - disrupts mitosis - inhibits growth
Ibuprofen - Naproxen - and Indomethacin
Increases mean - systolic - and diastolic bp - while there is little change in pulse pressure.

7. Digoxin v. Digitoxin: half life?
Digitoxin 168hrs Digoxin 40 hrs
- Methotrexate - 5 FU - 6 mercaptopurine
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone
Rapid (seconds)

8. Which drug(s) cause this reaction: Cutaneous flushing (4)?
Can affect absorption - bioavailability - or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying.
Hypersensitivity reactions
- Niacin - Ca++ channel blockers - adenosine - vancomycin
depresses ectopic pacemakers - especially in digoxin toxicity

9. What is the MOA of Ribavirin?
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome
Aplastic anemia (dose independent) - Gray Baby Syndrome
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis
G6PD deficient individuals

10. Furosemide increases the excretion of What ion?
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.
Ca2+ (Loops Lose calcium)
Keratin containing tissues - e.g. - nails
1. Renal damage 2. Aplastic anemia 3. GI distress

11. Adverse effects of Methyldopa?

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12. What is the major side effect for Carbenicillin - Piperacillin - and Ticarcillin?
Ceftriaxone
Severe Gram - rod infections.
proximal convoluted tubule - thin descending limb - and collecting duct
Hypersensitivity reactions

13. What are two clinical uses of Azathioprine?
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)
Binding to the presynaptic alpha 2 release modulating receptors
Bleeding.

14. List the specific antidote for this toxin: Methanol & Ethylene glycol
Tricyclic antidepressant.
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol
- Ethanol - dialysis - & fomepizole
cyanide toxicity (releases CN)

15. Which antimicrobials inhibit protein synthesis at the 50S subunit? (4)
1) Chloramphenical = bacteriostatic 2) Erythromycin = bacteriostatic 3) Lincomycin = bacteriostatic 4)cLindamycin = bacteriostatic
Methicillin - Nafcillin - and Dicloxacillin
GnRH analog with agonist properties When used in pulsatile fashion and antagonist properties When used in continuous fashion - causing a transient initial burst of LH and FSH
Lidocaine - Mexiletine - Tocainide

16. Would blockade of muscarininc receptors in the bladder be useful in treating urinary retention?
Binds Ergosterol - forms Membrane Pores that Disrupt Homeostatis
No. Atropine is used to reduce urgency in mild cystitis. So it would aggravate the urinary retention.
Hypersensitivity reactions
- Lithium

17. What is the memory key for organisms treated with Tetracyclines?

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18. What is the effect of norepinephrine on bp and pulse pressure?
Diuresis in pateints with sulfa allergy
Increases mean - systolic - and diastolic bp - while there is little change in pulse pressure.
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome
Fast vs. Slow Acetylators

19. Which drug(s) cause this reaction: Stevens - Johnson syn. (3)?
Chagas' disease - American Trypanosomiasis (Trypanosoma cruzi)
Nephrotoxicity (esp. with Cephalosporins) - Ototoxicity (esp. with Loop Diuretics)
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs
- Ethosuxamide - sulfonamides - lamotrigine

20. List the specific antidote for this toxin: Salicylates
Peptic ulcer disease.
- Alkalinize urine & dialysis
Systemic mycoses
Neomycin

21. What type of patient should not take Misoprostol and why?
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol
GET on the Metro
Misoprostol is contraindicated in women of childbearing potential because it is an abortifacient.
Increases mean - systolic - and diastolic bp - while there is little change in pulse pressure.

22. What is the category - method of use - and adverse effects of Salmeterol in Asthma treatment?
Cryptococcal meningitis in AIDS patients and Candidal infections of all types
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis
Beta1 more than B2
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.

23. Which drug(s) cause this reaction: Extrapyramidal side effects (3)?
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.
- Chlorpromazine - thioridazine - haloperidol
viral kinase
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis

24. How is Ganciclovir activated?
- Daunorubicin & Doxorubicin
Phosphorylation by a Viral Kinase
Parkinson patients benefit from antimuscarinic agents through its inhibitory action within the indirect pathway.
Acetylcholinesterase; ACh is broken down into choline and acetate.

25. Steady state concentration is reached in __ number of half - lifes
Rifampin
Acetylcholinesterase; ACh is broken down into choline and acetate.
In 4 half - lifes= (94%) T1/2 = (0.7x Vd)/CL
Aminoglycosides - Tetracyclines

26. What is a mnemonic to remember Amantadine's function?
GI upset
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.
Blocks Influenza A and RubellA; causes problems with the cerebellA
Diuresis in pateints with sulfa allergy

27. Which Aminoglycoside is used for Bowel Surgery ?
Hypersensitivity reactions
Neomycin
Stimulates beta adrenergic receptors
local anesthetic. CNS stimulation or depression. CV depression.

28. What are two toxicities of the Sulfonylureas?
Protamine sulfate
- Deferoxamine
is resistant
1. Hypoglycemia (more common with 2nd - generation drugs: glyburide - glipizide) 2. Disulfiram - like effects (not seen with 2nd - generation drugs).

29. How does NE modulate its own release? What other neurotransmitter has this same effect?
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
Protease inhibitor.
Ipratropium
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.

30. For Heparin What is the Site of action
Digitoxin 168hrs Digoxin 40 hrs
- N- acetylcystine
Penicillin - G
Blood

31. What is the category of drug names ending in - tropin (e.g. Somatotropin)
Pseudomembranous colitis (C. difficile) - fever - diarrhea
Pituitary hormone.
CL= (rate of elimination of drug/ Plasma drug conc.)
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine

32. What do you treat Nematode/roundworm (pinworm - whipworm) infections with?
GI disturbances.
Mebendazole/Thiabendazole - Pyrantel Pamoate
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine

33. What class of drug is echothiophate? What is its indication?
Beta adrenergic receptors and Ca2+ channels (stimulatory)
Nevirapine - Delavirdine
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis
anticholinesterase glaucoma

34. What is the category and mechanism of action of Zafirlukast in Asthma treatment?
PT
Antileukotriene; blocks leukotriene receptors.
Polymyxin B - Polymyxin E
loop diuretics - thiazides

35. Which antimuscarinic agents are used in producing mydriasis and cycloplegia?
Phase 1 = prolonged depolarization - no antidote - effect potentiated by anticholinesterase; Phase 2 = repolarized but blocked - an anticholinesterase is the antidote for this phase.
atropine - homatropine - tropicamide
Local anesthetic.
decrease conduction velocity - increase ERP - increase PR interval

36. Resistance mechanisms for Aminoglycosides
Modification via Acetylation - Adenylation - or Phosphorylation
Rare.
Similar to cyclosporine; binds to FK- binding protein - inhibiting secretion of IL-2 and other cytokines.
viral kinase

37. Which diuretics decrease urine Ca2+?
hyperchloremic metabolic acidosis - neuropathy - NH3 toxicity - sulfa allergy
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.
Anaerobes
thiazides - amiloride

38. What is the MOA for the Macrolides?
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic
GI discomfort
cardiac muscle: Verapamil>Diltiazem>Nifedipine
thick ascending limb

39. How does botulinum toxin result in respiratory arrest?
Prevents the release of ACh - Which results in muscle paralysis.
Epinephrine
- Methotrexate - 5 FU - 6 mercaptopurine
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions

40. What is Metronidazole used for clinically?
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.
Epinephrine to treat anaphylaxis. Also useful if you have open angle glaucoma - asthma - or hypotension.
Dopamine

41. Which drug(s) cause this reaction: Cough?
Beta -2 agonist.
Misoprostol is contraindicated in women of childbearing potential because it is an abortifacient.
- ACE inhibitors (Losartan>no cough)
Neutropenia

42. What is a Ribavirin toxicity?
Epinephirine(Alpha1 -2 and Beta 1 -2)
K+ wasting - metabolic alkalosis - hypotension - ototoxicity
Hemolytic anemia
Neutropenia (ticlopidine); reserved for those who cannot tolerate aspirin.

43. Secretion of What drug is inhibited by Probenacid used to treat chronic gout?
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.
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).
Penicillin.
Chronic (weeks or months)

44. What are three common NSAIDS other than Aspirin?
GI discomfort
1. Bleeding 2. Teratogenicity 3. Drug - drug interactions
Ibuprofen - Naproxen - and Indomethacin
NO HYPERURICEMIA - NO SULFA AllERGY; same as furosemide otherwise

45. For Heparin What is the Ability to inhibit coagulation in vitro
Protamine Sulfate is used for rapid reversal of heparinization (positively charged molecule that binds to negatively charged heparin).
Norepinephrine (Alpha1 -2 and beta 1)
Yes
- N- acetylcystine

46. Hydrochlorothiazide - clinical use?
HTN - CHF - calcium stone formation - nephrogenic DI.
Polymyxins
Chagas' disease - American Trypanosomiasis (Trypanosoma cruzi)
GET on the Metro

47. Name four Antiarrhythmic drugs in class III.
Inhibits bacterial Dihydrofolate Reductase - Bacteriostatic
- Glucagon
Inhibits cell wall synthesis ( binds to PBP3). A monobactam
Sotalol - Ibutilide - Bretylium - Amiodarone

48. What is the mecanism of action - effective period - and ineffective period of use for Cromolyn in treating Asthma?
Prevents release of mediators from mast cells. Effective only for the prophylaxis of asthma. Not effective during an acute attack.
Digitoxin>95% Digoxin 75%
ARF - shock - drug overdose - decrease intracranial/intraocular pressure
anuria - CHF

49. List the specific antidote for this toxin: Cyanide
- Nitrate - hydroxocobalamin thiosulfate
increase AP duration - increase ERP - increase QT interval - for use When other arrhythmics fail
It would increase to ~ 100 beats/min. Both sympathetic and vagal stimulation would be knocked out - but the SA node has an intrinsic pace of 100 beats/min - Which is normally checked by vagal stimulation.
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.

50. Spironolactone - mechanism?
competitive inhibirot of aldosterone in the cortical collecting tubule
Minor hepatotoxicity - Drug interactions (activates P450)
physostigmine
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.