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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. For Warfarin What is the Ability to inhibit coagulation in vitro
GI distress - Tooth discoloration and Inhibition of bone growth in children - Fanconi's syndrome - Photosensitivity
Cardiac glycoside (inotropic agent).
- Shifts the curve to the right - increases Km
No

2. What are two toxicities of the Glitazones?
1. Weight gain 2. Hepatotoxicity (troglitazone)
Prefers beta's at low doses - but at higher doses alpha agonist effects are predominantly seen.
Impairs the synthesis of vitamin K- dependent clotting factors
GI upset - Superinfections - Skin rashes - Headache - Dizziness

3. What is the memory key involving the '4 R's of Rifampin?'
Blocking muscarinic receptors in the circular fibers of the eye - results in unopposed action of radial muscles to dilate.
Indomethacin is used to close a patent ductus arteriosus.
impotence - exacerbation of asthma - CV effects - CNS effects - may mask hypoclycemia
1. RNA pol inhibitor 2. Revs up P450 3. Red/orange body fluids 4. Rapid resistance if used alone

4. Guanethidine enhances the release of Norepi?
- Oral Contraceptives
No - it inhibits the release of Nor Epi
Penicillin - V
Anaerobic infections (e.g. - B. fragilis - C. perfringens)

5. Beta Blockers - CNS toxicity?
sedation - sleep alterations
Gentamicin - Neomycin - Amikacin - Tobramycin - Streptomycin
Ototoxicity - Hypokalemia - Dehydration - Allergy (sulfa) - Nephritis (interstitial) - Gout
sedation - positive Coombs' test

6. What is the clinical use for Penicillin?
Bactericidal for: Gram + rod and cocci - Gram - cocci - and Spirochetes
Foscarnet = pyroFosphate analog
Tubocurarine - atracurium - mivacurium - pancuronium - vecuronium - rapacuronium
cyanide toxicity (releases CN)

7. What is the clinical utility of cocaine?
- Alkalates DNA - CML - Pulmonary fibrosis hyperpigmentation
The only local anesthetic with vasoconstrictive properties.
Primaquine
PT

8. What is the memory key for the effect of aluminum hydroxide overuse?
Post - op and neurogenic ileus and urinary retention - myasthenia gravis - and reversal of neuromuscular junction blockade (post - op) through anticholinesterase activity.
Dermatophytes (tinea - ringworm)
AluMINIMUM amount of feces.
Quinolones

9. Which antimuscarinic agents are used in producing mydriasis and cycloplegia?
Anaerobes
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow
reversible SLE- like syndrome
atropine - homatropine - tropicamide

10. If a patient is given hexamethonium - What would happen to his/her heart rate?
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.
Edrophonium
GI intolerance (nausea - diarrhea) - Hyperglycemia - Lipid abnormalities - Thrombocytopenia (Indinavir)
blocking the beta adrenergic receptor leads to decreased cAMP - and decreased Ca2+ flux

11. What is the mechanism of Azathioprine?
Only in limited amounts
Antimetabolite derivative of 6- mercaptopurine that interferes with the metablolism and synthesis of nucleic acid.
Triple sulfas or SMZ
Sulfonamides - Trimethoprim

12. What do Aminoglycosides require for uptake?
decrease conduction velocity - increase ERP - increase PR interval
Oral
Binds to the Pyrophosphate Binding Site of the enzyme
Oxygen

13. What is the lab value used to monitor the effectiveness of Warfarin therapy?
The PT.
Nephrotoxicity
Phenothiazine (neuroleptic - antiemetic).
Succinylcholine

14. What additional side effects exist for Ampicillin?
Rash - Pseudomembranous colitis
Long.
Suramin
Succinylcholine

15. How can the toxic effects of TMP be ameliorated?
With supplemental Folic Acid
Hydralazine and Minoxidil
The only local anesthetic with vasoconstrictive properties.
Sotalol - Ibutilide - Bretylium - Amiodarone

16. Foscarnet toxicity?
Nifedipine - Verapamil - Diltiazem
Nephrotoxicity
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.
GI discomfort - Acute cholestatic hepatitis - Eosinophilia - Skin rashes

17. How can Vancomycin - induced 'Red Man Syndrome' be prevented?
GI discomfort
Pretreat with antihistamines and a slow infusion rate
Oral treatment of superficial infections
Anaerobic infections (e.g. - B. fragilis - C. perfringens)

18. Acetazolamide - clinical uses?
glaucoma - urinary alkalinization - metabolic alkalosis - altitude sickness
1. Hot flashes 2. Ovarian enlargement 3. Multiple simultaneous pregnancies 4. Visual disturbances
narcolepsy - obesity - and attention deficit disorder (I wouldn't recommend this)
- Deferoxamine

19. What is a possible toxicity of Ticlopidine - Clopidogrel usage?
GI distress - Tooth discoloration and Inhibition of bone growth in children - Fanconi's syndrome - Photosensitivity
Interferes with microtubule function - disrupts mitosis - inhibits growth
Neutropenia (ticlopidine); reserved for those who cannot tolerate aspirin.
Fast vs. Slow Acetylators

20. How does a noncompetitive antagonist effect an agonist?
- ED 50 is less than the Km (less than 50% of receptors)
1) Chloramphenical = bacteriostatic 2) Erythromycin = bacteriostatic 3) Lincomycin = bacteriostatic 4)cLindamycin = bacteriostatic
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.
- Shifts the curve down - reduces Vmax

21. What is combination TMP- SMZ used to treat?
severe hypertension - CHF
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia
Muscarinic antagonist; competatively blocks muscarinic receptors - preventing bronchoconstriction.

22. What Sulfonamides are used for simple UTIs?
Triple sulfas or SMZ
- Tricyclic antidepressants
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.
- Tetracycline

23. Hydrochlorothiazide - mechanism?
Erectile dysfunction.
Ciprofloxacin - Norfloxacin - Ofloxacin - Grepafloxacin - Enoxacin - Nalidixic acid
Erythromycin - Azithromycin - Clarithromycin
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.

24. Which drug(s) cause this reaction: Gynecomastia (6)?
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis
- Normalize K+ - Lidocaine - & Anti - dig Mab
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens
AmOxicillin has greater Oral bioavailability

25. Quinidine - toxicity?
hypertension - CHF - diabetic renal disease
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval
Prefers beta's at low doses - but at higher doses alpha agonist effects are predominantly seen.
GI intolerance (nausea - diarrhea) - Hyperglycemia - Lipid abnormalities - Thrombocytopenia (Indinavir)

26. List the specific antidote for this toxin: Amphetamine
sedation - depression - nasal stuffiness - diarrhea
- Ammonium Chloride
Ataxia - Dizziness - Slurred speech
Bacitracin - Vancomycin

27. How do Sulfonamides act on bacteria?
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
Cyclooxygenases (COX I - COX II).
- ACE inhibitors (Losartan>no cough)
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)

28. Resistance mechanisms for Aminoglycosides
- Dimercaprol - succimer
Modification via Acetylation - Adenylation - or Phosphorylation
Polymyxin B - Polymyxin E
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.

29. Which drug(s) cause this reaction: Thrombotic complications?
Babiturate.
glaucoma - urinary alkalinization - metabolic alkalosis - altitude sickness
- Oral Contraceptives
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.

30. What are three complications of Warfarin usage?
1. Bleeding 2. Teratogenicity 3. Drug - drug interactions
Quinolones
Erythromycin - Azithromycin - Clarithromycin
- Penicillin

31. What microorganisms are Aminoglycosides ineffective against?
The only local anesthetic with vasoconstrictive properties.
- Acetaldehyde - Nausea - vomiting - headache - & hypotension
physostigmine
Anaerobes

32. Which antimicrobial classes inhibit protein synthesis at the 30S subunit? (2)
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic
- Ammonium Chloride
Cyclooxygenases (COX I - COX II).
Chronic (weeks or months)

33. What is the category - desired effect - and adverse effect of Isoproterenol in the treatment of Asthma?
- Bleomycin - amiodarone - busulfan
1)Binds penicillin - binding proteins 2) Blocks transpeptidase cross - linking of cell wall 3) Activates autolytic enzymes
Nonspecific beta - agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Adverse effect is tachycardia (Beta 1).
Nucleosides

34. What is the most common cause of Pt noncompliance with Macrolides?
TCA
GI discomfort
for RSV
It acts presynaptically to increase NE release.

35. What is the mechanism of action of the Sulfonylureas?
Butyrophenone (neuroleptic).
Bleeding.
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.
- inhibits HGPRT (pur. Syn.) - Luk - Lymph

36. What are five possible toxic effects of Aspirin therapy?

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37. What is the MOA of Aztreonam?
Inhibits cell wall synthesis ( binds to PBP3). A monobactam
Blood
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)

38. Name four Antiarrhythmic drugs in class III.
Gram + and Anerobes
Sotalol - Ibutilide - Bretylium - Amiodarone
Antibiotic - protein synthesis inhibitor.
AV nodal cells

39. What is the mechanism of action of Probenacid used to treat chronic gout?
Inhibits reabsorption of uric acid.
Tricyclic antidepressant.
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.
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.

40. What drug is given for Pneumocystis carinii prophylaxis?
Beta Blockers
impotence - asthma - CV effects (bradycardia - CHF - AV block) - CNS effects (sedation - sleep alterations)
Dopamine; causes its release from intact nerve terminals
Pentamidine

41. Adverse effect of Nitroprusside?
Bacitracin - Vancomycin
Hypokalemic metabolic alkalosis - hyponatremia - hyperGlycemia - hyperLipidemia - hyperUricemia - hyperCalcemia - sulfa allergy.
cyanide toxicity (releases CN)
Erythromycin - Azithromycin - Clarithromycin

42. For Warfarin What is the Structure
Small lipid - soluble molecule
1. Streptokinase 2. Urokinase 3. tPA (alteplase) - APSAC (anistreplase)
Cyclooxygenases (COX I - COX II).
Protamine sulfate

43. What are the clinical uses for Imipenem/cilastatin?
- Alkalates DNA - CML - Pulmonary fibrosis hyperpigmentation
Gram + cocci - Gram - rods - and Anerobes
sedation - sleep alterations
- Phase I (clinical tests) - Phase II - Phase III - PhaseIV (surveillance)

44. What is the MOA for the Aminoglycosides?
Inhibits formation of Initiation Complex - causes misreading of mRNA - Bactericidal
Rheumatoid and osteoarthritis.
- DNA intercalator - Hodgkin's - myeloma - sarcoma - and solid tumors - Cardiotoxicity & alopecia
Neutropenia

45. What neurotransmitter does Amantadine affect? How does it influence this NT?
Dopamine; causes its release from intact nerve terminals
SLUD (salivation - Lacrimation - urination - Defecation)as well as airway secretion - GI motility - acid secretions
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)
loop diuretics - thiazides

46. Which receptors does phenylephrine act upon?
first dose orthostatic hypotension - dizziness - headache
loop diuretics - spironolactone
Tricyclic antidepressant.
alpha -1 > alpha -2; used as a pupil dilator - vasoconstrictor - and for nasal decongestion

47. Which drug(s) cause this reaction: P450 inhibition(6)?
Systemic mycoses
hyperchloremic metabolic acidosis - neuropathy - NH3 toxicity - sulfa allergy
Primaquine
- Cimetidine - ketoconazole - grapefruit juice - erythromycin - INH - sulfonamides

48. 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)
HSV - VZV - EBV - Mucocutaneous and Genital Herpes Lesions - Prophylaxis in Immunocompromised pts
Reversible block of histamine H2 receptors
first dose orthostatic hypotension - dizziness - headache

49. What are two Alpha - glucosidase inhibitors?
Atropine pts are suffering from Cholinestrase inhibitor poisining (Nerve gas/Organophosphate poisining)
- Act on same receptor - Full has greater efficacy
Pseudomonas species and Gram - rods
1. Acarbose 2. Miglitol

50. How would you reverse the effect of a neuromuscular blocking agent?
Fluconazole - Ketoconazole - Clotrimazole - Miconazole - Itraconazole
Give an antichloinesterase - neostigmine - edrophonium - etc
The PT.
Chagas' disease - American Trypanosomiasis (Trypanosoma cruzi)