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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. Are penicillinase resistant
Methicillin - Nafcillin - and Dicloxacillin
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility
Ototoxicity - Hypokalemia - Dehydration - Allergy (sulfa) - Nephritis (interstitial) - Gout
- NaHCO3

2. What are two mechanisms of action of Propythiouracil?
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.
VACUUM your Bed Room'
Hypersensitivity reactions
Reserpine inhibits dopamine transport into vesicles - attenuating its conversion to NE by dopamine beta - hydroxylase.

3. Common toxicities associated with Griseofulvin?
Teratogenic - Carcinogenic - Confusion - Headaches
Blocks viral penetration/uncoating; may act to buffer the pH of the endosome
- Glucocorticoid withdrawal
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.

4. What is the MOA for Vancomycin?
Antileukotriene; blocks leukotriene receptors.
1. RNA pol inhibitor 2. Revs up P450 3. Red/orange body fluids 4. Rapid resistance if used alone
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium
Inhibits cell wall mucopeptide formation - Bactericidal

5. What is the difference between the affinity for beta receptors between albuterol/terbutaline and dantroline?
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.
- Lithium
Inhibit steroid synthesis - used in the treatment of polycystic ovarian syndrome to prevent hirsutism.
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia

6. Oral Penicillin
toxic
Acetylcholinesterase; ACh is broken down into choline and acetate.
Penicillin - V
Phenothiazine (neuroleptic - antiemetic).

7. What is action of insulin in the liver - in muscle - and in adipose tissue?
1. Gastric ulceration 2. Bleeding 3. Hyperventilation 4. Reye's syndrome 5. Tinnitus (CN VIII)
Spironolactone - Triamterene - Amiloride (the K+ STAys)
1. In liver - increases storage of glucose as glycogen. 2. In muscle - stimulates glycogen and protein synthesis - and K+ uptake. 3. In adipose tissue - facilitates triglyceride storage.
The PTT.

8. What are three complications of Warfarin usage?
Gram + cocci - Haemophilus influenza - Enterobacter aerogenes - Neisseria species - P. mirabilis - E. coli - K. pneumoniae - Serratia marcescens ( HEN PEcKS )
Fluconazole - Ketoconazole - Clotrimazole - Miconazole - Itraconazole
1. Bleeding 2. Teratogenicity 3. Drug - drug interactions
1) Hypersensitivity reactions 2) Increased nephrotoxicity of Aminoglycosides 3) Disulfiram - like reaction with ethanol (those with a methylthiotetrazole group - e.g. - cefamandole)

9. What is clinical use for Carbenicillin - Piperacillin - and Ticarcillin?
Pseudomonas species and Gram - rods
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic
HTN - CHF - calcium stone formation - nephrogenic DI.
DOC in diagnosing and abolishing AV nodal arrhythmias

10. Which drug(s) cause this reaction: Cutaneous flushing (4)?
No. Atropine is used to reduce urgency in mild cystitis. So it would aggravate the urinary retention.
- Niacin - Ca++ channel blockers - adenosine - vancomycin
No - it inhibits the release of Nor Epi
Triple Therapy' 2 Nucleoside RT Inhibitors with a Protease Inhibitor

11. What are common side effects of Protease Inhibitors?
Ototoxicity - Hypokalemia - Dehydration - Allergy (sulfa) - Nephritis (interstitial) - Gout
GI intolerance (nausea - diarrhea) - Hyperglycemia - Lipid abnormalities - Thrombocytopenia (Indinavir)
Nifedipine - Verapamil - Diltiazem
TMP- SMZ (DOC) - aerosolized pentamidine

12. What is the category of drug names ending in - tidine (e.g. Cimetidine)
Cardiac glycoside (inotropic agent).
Ceftriaxone
H2 antagonist
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens

13. What is the MOA for Acyclovir?
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia
- Tetracycline
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow
Inhibit viral DNA polymerase

14. What drug is used during the pregnancy of an HIV+ mother? - Why?
Competitive inibitor of progestins at progesterone receptors.
Na/K ATPase
AZT - to reduce risk of Fetal Transmission
NO AP duration effect. useful in V- tach that progresses to V- fib and in intractable SVT Last RESORT

15. Resistance mechanisms for Tetracycline
Decreased uptake or Increased transport out of cell
- Penicillamine
Cardiac glycoside (inotropic agent).
decrease the slope of phase 4 - increase PR interval (the AV node is particularly sensitive)

16. Digoxin v. Digitoxin: excretion?
Erectile dysfunction.
sedation - positive Coombs' test
Gram + and Anerobes
Digoxin=urinary Digitoxin=biliary

17. What is the clinical use for Ampicillin and Amoxicillin?
Penicillin - G
Penicillin - V
Extended spectrum penicillin: certain Gram + bacteria and Gram - rods
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels

18. What are four Sulfonylureas?
amphetamine and ephedrine
- Nitrate - hydroxocobalamin thiosulfate
Impairs the synthesis of vitamin K- dependent clotting factors
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide

19. Why would you use pralidoxime after exposure to an organophosphate?
viral kinase
Pralidoxime regenerates active cholinesterase.
Chronic (weeks or months)
1. Antiandrogen 2. Nausea 3. Vomiting

20. Specifically - How does Foscarnet inhibit viral DNA pol?
Peptic ulcer disease.
Binds to the Pyrophosphate Binding Site of the enzyme
Forms toxic metabolites in the bacterial cell - Bactericidal
With supplemental Folic Acid

21. What is an acronym to remember Anti - TB drugs?
Ipratropium
Resistant Gram - infections
Rifampin
RESPIre

22. Which drug(s) cause this reaction: Gray baby syndrome?
- Chloramphenicol
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis
carbonic anhydrase inhibitors - K+ sparing diuretics
Triple Therapy' 2 Nucleoside RT Inhibitors with a Protease Inhibitor

23. For Warfarin What is the Ability to inhibit coagulation in vitro
-100% oxygen - hyperbaric
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs
- aminoglycosides - loop diuretics - cisplatin
No

24. What microorganisms is Aztreonam not effective against?
- inhibits HGPRT (pur. Syn.) - Luk - Lymph
Gram + and Anerobes
Flecainide - Encainide - Propafenone
Hemolytic anemia

25. What is the clinical use for Clomiphene?
Give an antichloinesterase - neostigmine - edrophonium - etc
BM suppression (neutropenia - anemia) - Peripheral neuropathy
Treatment of infertility.
Inhibits cell wall mucopeptide formation - Bactericidal

26. Ethacrynic Acid - mechanism?
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.
As an anticholinesterase it increases endogenous ACh and thus increases strength.
Quinidine - Amiodarone - Procainamide - Disopyramide
not a sulfonamide - but action is the same as furosemide

27. Clonidine is the preferred sym pathomimetic tx of HTN in pts with renal disease - why??
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow
Inhibits cGMP phosphodiesterase - casuing increased cGMP - smooth muscle relaxation in the corpus cavernosum - increased blood flow - and penile erection.
GI distress - Skin rash - and Seizures at high plasma levels
Inhibits reabsorption of uric acid.

28. Digoxin v. Digitoxin: bioavailability?
Modification via Acetylation - Adenylation - or Phosphorylation
hyperaldosteronism - K+ depletion - CHF
Digitoxin>95% Digoxin 75%
- Aminocaproic acid

29. What drug is used to diagnose myasthenia gravis?
ACIDazolamide' causes acidosis
Buy AT 30 - CELL at 50'
edrophonium (extremely short acting anticholinesterase)
- Acetaldehyde - Nausea - vomiting - headache - & hypotension

30. List the specific antidote for this toxin: Lead
Benzodiazepine.
- EDTA - dimercaprol - succimer - & penicillamine
- Alkalinize urine & dialysis
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.)

31. What is the memory key for Isoniazid (INH) toxicity?
INH: Injures Neurons and Hepatocytes
viral kinase
- aminoglycosides - loop diuretics - cisplatin
Mg = Must go to the bathroom.

32. What is the mechanism of Leuprolide?
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia
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
- Tetracycline - amiodarone - sulfonamides
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more

33. Resistance mechanisms for Macrolides

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34. Which individuals are predisposed to Sulfonamide - induced hemolysis?
CMV Retinitis in IC pts When Ganciclovir fails
cardiac muscle: Verapamil>Diltiazem>Nifedipine
Stimulates beta adrenergic receptors
G6PD deficient individuals

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

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36. Name some common Tetracyclines (4)
sedation - positive Coombs' test
fetal renal toxicity - hyperkalemia
Tetracycline - Doxycycline - Demeclocycline - Minocycline
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.

37. What is Niclosamide used for?
fetal renal toxicity - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.
Pretreat with antihistamines and a slow infusion rate

38. ACE inhibitors - mechanism?
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased
sedation - sleep alterations
Triple sulfas or SMZ
- Vitamin K & fresh frozen plasma

39. Name the common Non - Nucleoside Reverse Transcriptase Inhibitors
Nevirapine - Delavirdine
Hexamethonium is a nicotinic antagonist - and thus is a ganglionic blocker.
Pretreat with antihistamines and a slow infusion rate
GI upset - Superinfections - Skin rashes - Headache - Dizziness

40. What is the category of drug names ending in - zosin (e.g. Prazosin)
Ciprofloxacin - Norfloxacin - Ofloxacin - Grepafloxacin - Enoxacin - Nalidixic acid
Aminoglycosides - Tetracyclines
Alpha -1 antagonist
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.

41. Which drug(s) cause this reaction: Tubulointerstitial Nephritis (5)?
Warfarin interferes with the normal synthesis and gamma - carboxylation of vitamin K- dependent clotting factors II - VII - IX - and X - Protein C and S via vitamin K antagonism.
- Chloramphenicol - benzene - NSAIDS - PTU - phenytoin
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)
Modification via Acetylation

42. What is the mechanism of action of Probenacid used to treat chronic gout?
effective in torsade de pointes and digoxin toxicity
Inhibits reabsorption of uric acid.
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.
Disulfiram - like reaction with EtOH - Headache

43. What is the category of drug names ending in - oxin (e.g. Digoxin)
alpha -1 > alpha -2; used as a pupil dilator - vasoconstrictor - and for nasal decongestion
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)
Cardiac glycoside (inotropic agent).

44. What are the clinical uses for 1st Generation Cephalosporins?
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis
Gram + cocci - Proteus mirabilis - E. coli - Klebsiella pneumoniae (PEcK)
Potent immunosuppressive used in organ transplant recipients.
Inhibits Viral DNA polymerase

45. Ca2+ channel blockers - mechanism?
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.
Chronic (weeks or months)
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.

46. List the specific antidote for this toxin: Beta Blockers
Cardiac glycoside (inotropic agent).
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more
Prevents the release of Ca from SR of skeletal muscle
- Glucagon

47. Loop diuretics (furosemide)- site of action?
cortical collecting tubule
Hemolytic anemia
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis
thick ascending limb

48. What do Aminoglycosides require for uptake?
Amphotericin B - Nystatin - Fluconazole/azoles
Oxygen
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.
- Phase I (clinical tests) - Phase II - Phase III - PhaseIV (surveillance)

49. Does Ampicillin or Amoxicillin have a greater oral bioavailability?
hyperkalemia - endocrine effects (gynecomastia - anti - androgen)
Same as penicillin. Extended spectrum antibiotics
AmOxicillin has greater Oral bioavailability
Staphlococcus aureus

50. How can Vancomycin - induced 'Red Man Syndrome' be prevented?
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.)
Pretreat with antihistamines and a slow infusion rate
pulmonary edema - dehydration
Milk or Antacids - because divalent cations inhibit Tetracycline absorption in the gut