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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. What are common toxicities related to Vancomycin therapy?

2. Ethacrynic Acid - mechanism?
Teratogenic - Carcinogenic - Confusion - Headaches
GI discomfort
- Hypersensitivity reactions - Hemolysis - Nephrotoxicity (tubulointerstitial nephritis) - Kernicterus in infants Displace other drugs from albumin (e.g. - warfarin)
not a sulfonamide - but action is the same as furosemide

3. A 57 yo heart failure pt develops cardiac decompensation - What drug will give you adequate perfusion of his kidneys as well as tx for his Hypotension
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels
Dopamine
torsade de pointes - excessive Beta block

4. K+ sparing diuretics - clinical use?
1. Hot flashes 2. Ovarian enlargement 3. Multiple simultaneous pregnancies 4. Visual disturbances
Foscarnet = pyroFosphate analog
hyperaldosteronism - K+ depletion - CHF
Give an antichloinesterase - neostigmine - edrophonium - etc

5. What are two Glitazones?
Epinephrine
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine
1. Pioglitazone 2. Rosiglitazone.
Carbachol - pilocarpine - physostigmine - echothiophate

6. ADH antagonists - site of action?
Na/K ATPase
Beta lactams - inhibit cell wall synthesis - Bactericidal
collecting ducts
narcolepsy - obesity - and attention deficit disorder (I wouldn't recommend this)

7. What do you treat Nematode/roundworm (pinworm - whipworm) infections with?
- Penicillamine
Prevents the release of ACh - Which results in muscle paralysis.
Pseudomonas species and Gram - rods
Mebendazole/Thiabendazole - Pyrantel Pamoate

8. What is combination TMP- SMZ used to treat?
- Upper respiratory tract infections - pneumonias - STDs: Gram+ cocci (streptococcal infect in pts allergic to penicillin) - Mycoplasma - Legionella - Chlamydia - Neisseria
check PFTs - LFTs - and TFTs
1. Streptokinase 2. Urokinase 3. tPA (alteplase) - APSAC (anistreplase)
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia

9. Why would dopamine be useful in treating shock?
Lidocaine - Mexiletine - Tocainide
thiazides - amiloride
Inhibit viral DNA polymerase
Receptors = D1=D2>beta>alpha - thus increasing heart rate (beta) and blood pressure (alpha vasoconstriction) while maintaining kidney perfusion (dopamine receptors)

10. What two vasodilators require simultaneous treatment with beta blockers to prevent reflex tachycardia and diuretics to prevent salt retention?
Hydralazine and Minoxidil
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow
post MI and digitalis induced arrhythmias
Hypersensitivity reactions

11. What is the category - mechanism of action - and effect of Ipratroprium in Asthma treatment?
1. Skin rash 2. Agranulocytosis (rare) 3. Aplastic anemia
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions
Hemolytic anemia
Muscarinic antagonist; competatively blocks muscarinic receptors - preventing bronchoconstriction.

12. Toxic side effects of the Azoles?
Hormone synthesis inhibition (Gynecomastia) - Liver dysfunction (Inhibits CYP450) - Fever - Chills
Penicillin - G
Muscarinic antagonist; competatively blocks muscarinic receptors - preventing bronchoconstriction.
- Cloazapine - carbamazapine - colchicine - PTU

13. Why is carbachol and pilocarpine useful in treatment of glaucoma?
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).
Hypersensitivity reactions
GI distress - Tooth discoloration and Inhibition of bone growth in children - Fanconi's syndrome - Photosensitivity
These B-2 agonists cause respiratory smooth muscle to relax.

14. Cocaine shares is mechanism of action with What antidepressant
Small lipid - soluble molecule
- Oral Contraceptives
-100% oxygen - hyperbaric
TCA

15. What is a Ribavirin toxicity?
Hemolytic anemia
is resistant
Inhibits cell wall synthesis ( binds to PBP3). A monobactam
Same as penicillin. Extended spectrum antibiotics

16. ___________ are Teratogenic
Same as penicillin. Extended spectrum antibiotics
Aminoglycosides
thiazides - amiloride
fetal renal toxicity - hyperkalemia

17. Are penicillinase resistant
Used in combination therapy with SMZ to sequentially block folate synthesis
Digoxin=urinary Digitoxin=biliary
Doxycycline - because it is fecally eliminated
Methicillin - Nafcillin - and Dicloxacillin

18. MOA: Block peptidoglycan synthesis
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).
- Shifts the curve down - reduces Vmax
Bacitracin - Vancomycin
Hypersensitivity reactions

19. Which drug(s) cause this reaction: G6PD hemolysis(8)?
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions
Carbachol - pilocarpine - physostigmine - echothiophate
- Chloramphenicol - benzene - NSAIDS - PTU - phenytoin
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol

20. How does botulinum toxin result in respiratory arrest?
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis
Ataxia - Dizziness - Slurred speech
Chagas' disease - American Trypanosomiasis (Trypanosoma cruzi)
Prevents the release of ACh - Which results in muscle paralysis.

21. What is the MOA for Metronidazole?
loop diuretics - spironolactone
Forms toxic metabolites in the bacterial cell - Bactericidal
Blocks viral penetration/uncoating; may act to buffer the pH of the endosome
CMV Retinitis in IC pts When Ganciclovir fails

22. What is the effect of the Glitazones in diabetes treatment?
Local anesthetic.
Increase target cell response to insulin.
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).
Chronic gout.

23. What is a sign of toxicity with the use of thrombolytics?
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.
- Upper respiratory tract infections - pneumonias - STDs: Gram+ cocci (streptococcal infect in pts allergic to penicillin) - Mycoplasma - Legionella - Chlamydia - Neisseria
Bleeding.
The PTT.

24. Which drug increases Sys BP w/o affecting Pulse Pressure
- acetylation - glucuron. - & sulfation - Conjugation - Polar product
Anaerobes
Epinephrine
Erectile dysfunction.

25. Why would a patient with cog - wheel rigidity and a shuffling gait be given benztropine?
Parkinson patients benefit from antimuscarinic agents through its inhibitory action within the indirect pathway.
Only in limited amounts
Norepinephrine
Inhibits CMV DNA polymerase

26. What class of drug is echothiophate? What is its indication?
anticholinesterase glaucoma
Pretreat with antihistamines and a slow infusion rate
Same as penicillin. Extended spectrum antibiotics
- Flumazenil

27. List the specific antidote for this toxin: Anticholinesterases (organophosphate.)
Pretreat with antihistamines and a slow infusion rate
Cilastatin
Nucleosides
- Atropine & pralidoxime

28. Which RT inhibitors cause a Rash?
Neomycin
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.
Non - Nucleosides
Diarrhea

29. How can Isoniazid (INH)- induced neurotoxicity be prevented?
Pyridoxine (B6) administration
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia
torsade de pointes
- Glucocorticoid withdrawal

30. Why does atropine dilate the pupil?
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).
Sildenafil fills the penis
Blocking muscarinic receptors in the circular fibers of the eye - results in unopposed action of radial muscles to dilate.
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia

31. What is the major side effect for Ampicillin and Amoxicillin?
Hypersensitivity reactions
CMV Retinitis in IC pts When Ganciclovir fails
is resistant
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.

32. What is the mechanism of action of Ticlopidine - Clopidogrel
- Ethanol - dialysis - & fomepizole
- Phenytoin
Diuresis in pateints with sulfa allergy
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.

33. What drug is given for Pneumocystis carinii prophylaxis?
Lidocaine - Mexiletine - Tocainide
Penicillin - Ampicillin - Ticarcillin - Pipercillin - Imipenem - Aztreonam - Cephalosporins
Pentamidine
Antileukotriene; blocks synthesis by lipoxygenase.

34. List the specific antidote for this toxin: Methemoglobin
- Methylene blue
Ld= (CpxVd)/F Cp=plasma conc. F= Bioaval.
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis
- Oral Contraceptives

35. For Warfarin What is the Ability to inhibit coagulation in vitro
No
post MI and digitalis induced arrhythmias
Aminoglycosides
Cyclooxygenases (COX I - COX II).

36. List five common glucocorticoids.
GI upset - Superinfections - Skin rashes - Headache - Dizziness
Irreversibly inhibits H+/K+ ATPase in stomach parietal cells.
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone
Digitoxin 168hrs Digoxin 40 hrs

37. What is the mechanism of action of the H2 Blockers?
Reversible block of histamine H2 receptors
DHPG (dihydroxy-2- propoxymethyl guanine)
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.
Can affect absorption - bioavailability - or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying.

38. Guanethidine enhances the release of Norepi?
No - it inhibits the release of Nor Epi
Finasteride inhibits 5 Alpha - reductase - this decreases the conversion of testosterone to dihydrotestosterone - useful in BPH
depresses ectopic pacemakers - especially in digoxin toxicity
Directly of indirectly aid conversion of plasminogen to plasmin Which cleaves thrombin and fibrin clots. (It is claimed that tPA specifically converts fibrin - bound plasminogen to plasmin.)

39. MOA: Block DNA topoisomerases
cortical collecting tubule
In 4 half - lifes= (94%) T1/2 = (0.7x Vd)/CL
Tetracycline - Doxycycline - Demeclocycline - Minocycline
Quinolones

40. What is the MOA for Carbenicillin - Piperacillin - and Ticarcillin?
Bleeding.
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.
Does not cross
Same as penicillin. Extended spectrum antibiotics

41. What microorganisms are clinical indications for Tetracycline therapy?

42. Preferential action of the Ca2+ channel blockers at cardiac muscle?
cardiac muscle: Verapamil>Diltiazem>Nifedipine
Hypersensitivity reactions
troponin - tropomyosin system
amphetamine and ephedrine

43. Resistance mechanisms for Aminoglycosides
is resistant
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
Modification via Acetylation - Adenylation - or Phosphorylation
Blocks Influenza A and RubellA; causes problems with the cerebellA

44. Triamterene and amiloride - mechanism?
Norepinephrine
cross - allergenic
block Na+ channels in the cortical collecting tubule
loop diuretics - spironolactone

45. What are are the Sulfonylureas (general description) and What is their use?
Immediate anticoagulation for PE - stroke - angina - MI - DVT.
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
Oxygen

46. What is the MOA of Ribavirin?
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis
Systemic mycoses
Blocks Peptide Bond formation at the 50S subunit - Bacteriostatic
- Aminocaproic acid

47. Specifically - How does Foscarnet inhibit viral DNA pol?
Binds to the Pyrophosphate Binding Site of the enzyme
loop diuretics - spironolactone
Indirect agonist - uptake inhibitor
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.

48. MOA: Block protein synthesis at 50s subunit
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
- Fluoroquinolones
Anaerobic infections (e.g. - B. fragilis - C. perfringens)
sedation - positive Coombs' test

49. Name the common Non - Nucleoside Reverse Transcriptase Inhibitors
Nevirapine - Delavirdine
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.
blocks SR Ca2+ channels
Onchocerciasis ('river blindness'-- rIVER- mectin)

50. What are Methicillin - Nafcillin - and Dicloxacillin used for clinically?
Staphlococcus aureus
Rheumatoid and osteoarthritis.
Nucleosides
impotence - asthma - CV effects (bradycardia - CHF - AV block) - CNS effects (sedation - sleep alterations)