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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 is Fluconazole specifically used for?
Nevirapine - Delavirdine
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium
Cryptococcal meningitis in AIDS patients and Candidal infections of all types
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.

2. K+ sparing diuretics - toxicity?
- Tamoxifen
hyperkalemia - endocrine effects (gynecomastia - anti - androgen)
Verapamil - Diltiazem - Bepridil
No

3. What is Metronidazole combined with for 'triple therapy'? Against What organism?
Bismuth and Amoxicillin or Tetracycline; against Helobacter pylori
Antileukotriene; blocks leukotriene receptors.
effective in torsade de pointes and digoxin toxicity
GI discomfort

4. How is Leishmaniasis treated?
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine
Pentavalent Antimony
AZT
Increase target cell response to insulin.

5. Antiarrhythmic class II- toxicity?
Impairs the synthesis of vitamin K- dependent clotting factors
- Methylene blue
increase AP duration - increase ERP - increase QT interval - for use When other arrhythmics fail
impotence - exacerbation of asthma - CV effects - CNS effects - may mask hypoclycemia

6. What is Clindamycin used for clinically?
decrease conduction velocity - increase ERP - increase PR interval
Anaerobic infections (e.g. - B. fragilis - C. perfringens)
Diarrhea
Used in combination therapy with SMZ to sequentially block folate synthesis

7. What is the mechanism of action of Probenacid used to treat chronic gout?
Epinephrine to treat anaphylaxis. Also useful if you have open angle glaucoma - asthma - or hypotension.
Chronic gout.
Inhibits reabsorption of uric acid.
Diuresis in pateints with sulfa allergy

8. Name the common Fluoroquinolones (6)
ACIDazolamide' causes acidosis
Ciprofloxacin - Norfloxacin - Ofloxacin - Grepafloxacin - Enoxacin - Nalidixic acid
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow
Severe Gram - rod infections.

9. What is the MOA of Isoniazid (INH)?
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
Decreases synthesis of Mycolic Acid
- Daunorubicin & Doxorubicin
Digitoxin 168hrs Digoxin 40 hrs

10. Which drug(s) cause this reaction: Tardive dyskinesia?
Blood
- Antipsychotics
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).
Epinephirine(Alpha1 -2 and Beta 1 -2)

11. What is the mechanism of Azathioprine?
Pentavalent Antimony
Antimetabolite derivative of 6- mercaptopurine that interferes with the metablolism and synthesis of nucleic acid.
Acute (hours)
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity

12. Resistance mechanisms for Chloramphenicol
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
Modification via Acetylation
Cephalosporins
1. Predisposes to viral infections and lymphoma 2. Nephrotoxic (preventable with mannitol diuresis)

13. What are two processes Corticosteroids inhibit leading to decreased inflammation?
Inhibit DNA Gyrase (topoisomerase II) - Bactericidal
Beta -2 agonist.
1. Phospholipase A2 is prevented from releasing arachidonic acid 2. Decreases protein synthesis thus lowering amount of Cyclooxygenase enzymes
- Fluoroquinolones

14. What Sulfonamides are used for simple UTIs?
NO AP duration effect. useful in V- tach that progresses to V- fib and in intractable SVT Last RESORT
Triple sulfas or SMZ
Beta - lactam antibiotics
cardiac depression - peripheral edema - flushing - dizziness - constipation

15. Mannitol - clinical use?
Chronic Hepatitis A and B - Kaposi's Sarcoma
- DNA intercalator - testicular & lymphomas - Pulmonary fibrosis mild myelosuppression.
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.
ARF - shock - drug overdose - decrease intracranial/intraocular pressure

16. What is the MOA for the Tetracyclines?
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents
first dose orthostatic hypotension - dizziness - headache

17. For Warfarin What is the Structure
Amphetamine and Ephedrine
Small lipid - soluble molecule
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.
Bethanechol - Neostigmine - physostigmine

18. Mannitol - site of action?
Headache - flushing - dyspepsia - blue - green color vision.
proximal convoluted tubule - thin descending limb - and collecting duct
Competitive inibitor of progestins at progesterone receptors.
Giardiasis - Amoebic dysentery (E. histolytica) - Bacterial vaginitis (Gardnerella vaginalis) - Trichomonas

19. What is Niclosamide used for?
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity
Sildenafil fills the penis
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis
Potent immunosuppressive used in organ transplant recipients.

20. What are two indirect acting adrenergic agonists?
Cell membrane Ca2+ channels of cardiac sarcomere
Amphotericin B - Nystatin - Fluconazole/azoles
amphetamine and ephedrine
Sulfonamides - Trimethoprim

21. What cholinergic inhibitor acts by directly inhibiting Ach release at the presynaptic terminal
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors
Clavulanic acid
Botulinum
Fluconazole - Ketoconazole - Clotrimazole - Miconazole - Itraconazole

22. Which drug(s) cause this reaction: Pseudomembranous colitis?
- Clindamycin
Impairs the synthesis of vitamin K- dependent clotting factors
- Formaldehyde & formic acid - severe acidosis & retinal damage
Digitoxin 70% Digoxin 20-40%

23. How can Isoniazid (INH)- induced neurotoxicity be prevented?
Large anionic polymer - acidic
Blocks Norepi - but not Dopamine
Pyridoxine (B6) administration
Carbenicillin - Piperacillin - and Ticarcillin

24. Describe Phase I metabolism in liver(3)?
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.
No - warfarin - unlike heparin - can cross the placenta.
depresses ectopic pacemakers - especially in digoxin toxicity
- reduction - oxy - & hydrolysis - H2O sol. Polar product - P450

25. What antimicrobial class is Aztreonam syngergestic with?
- Clindamycin
Acetaminophen has antipyretic and analgesic properties - but lacks anti - inflammatory properties.
cardiac depression - peripheral edema - flushing - dizziness - constipation
Aminoglycosides

26. What is a common side effect of Colchicine used to treat acute gout - especially When given orally?
Lipoxygenase
GI side effects. (Indomethacin is less toxic - more commonly used.)
- EDTA - dimercaprol - succimer - & penicillamine
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.

27. How are the HIV drugs used clinically?

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28. What is the memory aid for subunit distribution of ribosomal inhibitors?

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29. What are Methicillin - Nafcillin - and Dicloxacillin used for clinically?
Staphlococcus aureus
- Penicillin
very short acting
Digoxin=urinary Digitoxin=biliary

30. Does Heparin have a long - medium - or short half life?
Pyridoxine (B6) administration
Penicillin - Cephalosporins - Vancomycin - Aminoglycosides - Fluoroquinolones - Metronidazole
Topical and Oral - for Oral Candidiasis (Thrush)
Short.

31. Acetazolamide - mechanism?
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.
Extended spectrum penicillin: certain Gram + bacteria and Gram - rods
- acetylation - glucuron. - & sulfation - Conjugation - Polar product
- Protamine

32. How do we stop angina?
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time
TCA

33. Beta Blockers - CNS toxicity?
Prevents the release of ACh - Which results in muscle paralysis.
loop diuretics - thiazides
Foscarnet = pyroFosphate analog
sedation - sleep alterations

34. Common toxicities associated with Griseofulvin?
No - warfarin - unlike heparin - can cross the placenta.
- Disulfram & also sulfonylureas - metronidazole
Teratogenic - Carcinogenic - Confusion - Headaches
amphetamine and ephedrine

35. How is Ganciclovir used clinically?
Premature infants - because they lack UDP- glucuronyl transferase
CMV - esp in Immunocompromised patients
Penicillin - G
Same as penicillin. Act as narrow spectrum antibiotics

36. What are are the Sulfonylureas (general description) and What is their use?
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
Prevention of NSAID- induced peptic ulcers - maintains a PDA.
Acetylcholinesterase; ACh is broken down into choline and acetate.
aPTT (intrinsic pathway)

37. Ethacrynic Acid - clinical use?
Diuresis in pateints with sulfa allergy
The PT.
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)
loop diuretics - spironolactone

38. How would you treat African Trypanosomiasis (sleeping sickness)?
Norepinephrine (Alpha1 -2 and beta 1)
Suramin
With supplemental Folic Acid
Modification via Acetylation - Adenylation - or Phosphorylation

39. K+- clinical use?
Increase target cell response to insulin.
depresses ectopic pacemakers - especially in digoxin toxicity
AZT - to reduce risk of Fetal Transmission
Liver

40. List the specific antidote for this toxin: Anticholinesterases (organophosphate.)
Norepinephrine
- Bleomycin - amiodarone - busulfan
- Atropine & pralidoxime
Polymyxin B - Polymyxin E

41. What is a common drug interaction associated with Griseofulvin?
- Estrogen receptor antagonist - Breast CA - increased endometrial CA risk
not a sulfonamide - but action is the same as furosemide
The PTT.
Increases coumadin metabolism

42. List the mechanism - clinical use - & toxicity of Bleomycin.
compensatory tachycardia - fluid retention - lupus - like syndrome
HSV - VZV - EBV - Mucocutaneous and Genital Herpes Lesions - Prophylaxis in Immunocompromised pts
To inhibit renal Dihydropeptidase I and decrease Imipenem inactivation in the renal tubules
- DNA intercalator - testicular & lymphomas - Pulmonary fibrosis mild myelosuppression.

43. Name three Antiarrhythmic drugs in class IB.
Botulinum
Protease Inhibitors and Reverse Transcriptase Inhibitors
- Penicillin
Lidocaine - Mexiletine - Tocainide

44. For Heparin What is the Route of administration
Paranteral (IV - SC)
1. Acarbose 2. Miglitol
- EDTA - dimercaprol - succimer - & penicillamine
Norepinephrine

45. List the specific antidote for this toxin: Warfarin
Penicillin - G
prevention of nodal arrhythmias (SVT)
- Aminocaproic acid
- Vitamin K & fresh frozen plasma

46. K+ sparing diuretics - site of action?
1. Addison's disease 2. Inflammation 3. Immune suppression 4. Asthma
cortical collecting tubule
Inhibits formation of Initiation Complex - causes misreading of mRNA - Bactericidal
Beta -2 agonist.

47. What is the formula for Clearance (CL)
CL= (rate of elimination of drug/ Plasma drug conc.)
Blocks Norepi - but not Dopamine
Foscarnet = pyroFosphate analog
Beta antagonist.

48. What are the Anti - TB drugs?
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.
Rifampin - Ethambutol - Streptomycin - Pyrazinamide - Isoniazid (INH)
Tricyclic antidepressant.
cyanide toxicity (releases CN)

49. What reversal agent could a Anes give to reverse the effects of Atropine
Bethanechol - Neostigmine - physostigmine
Oral
Beta adrenergic receptors and Ca2+ channels (stimulatory)
Indomethacin is used to close a patent ductus arteriosus.

50. What is the effect of the Glitazones in diabetes treatment?
The PT.
Increase target cell response to insulin.
- reduction - oxy - & hydrolysis - H2O sol. Polar product - P450
Blocks viral penetration/uncoating; may act to buffer the pH of the endosome