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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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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. Which antimicrobial classes inhibit protein synthesis at the 30S subunit? (2)
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.
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic
Hypersensitivity reactions
-100% oxygen - hyperbaric

2. List the specific antidote for this toxin: Lead
- EDTA - dimercaprol - succimer - & penicillamine
Prevents the release of ACh - Which results in muscle paralysis.
Increase target cell response to insulin.
Beta Blockers

3. List the mechanism - clinical use - & toxicity of Doxorubicin.

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4. Why is Cilastatin administered with Imipenem?
Methicillin - Nafcillin - and Dicloxacillin
Milk or Antacids - because divalent cations inhibit Tetracycline absorption in the gut
To inhibit renal Dihydropeptidase I and decrease Imipenem inactivation in the renal tubules
Rare.

5. Which Tetracycline is used in patients with renal failure? / Why?
- Nitrate - hydroxocobalamin thiosulfate
Doxycycline - because it is fecally eliminated
It inhibits release of NE.
NO

6. What is Fluconazole specifically used for?
- polymyxins
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels
Cryptococcal meningitis in AIDS patients and Candidal infections of all types
- Alkalates DNA - CML - Pulmonary fibrosis hyperpigmentation

7. What are five toxicities associated with Tacrolimus (FK506)?
Acute gout.
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.
Enterobacter
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.

8. Name the common Non - Nucleoside Reverse Transcriptase Inhibitors
Nevirapine - Delavirdine
1. Acarbose 2. Miglitol
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.
alpha -1 > alpha -2; used as a pupil dilator - vasoconstrictor - and for nasal decongestion

9. Hydralazine - toxicity?
compensatory tachycardia - fluid retention - lupus - like syndrome
Malaria (P. falciparum)
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.
Penicillin.

10. How are the HIV drugs used clinically?

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11. What is the mechanism of action of the Sulfonylureas?
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.
- Fluoroquinolones
Penicillin.
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis

12. List five common glucocorticoids.
Sulfonamides - Trimethoprim
ACIDazolamide' causes acidosis
Anaerobic infections (e.g. - B. fragilis - C. perfringens)
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone

13. What type of gout is treated with Colchicine?
Acute gout.
Interferes with microtubule function - disrupts mitosis - inhibits growth
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
Rare.

14. What patients are at risk for life threatening hypotension When taking Sildenafil (Viagra)?
Nephrotoxicity
Disulfiram - like reaction with EtOH - Headache
Inhibits Viral DNA polymerase
Those patients who are taking nitrates.

15. Ethacrynic Acid - clinical use?
Diuresis in pateints with sulfa allergy
increase AP duration - increase ERP - increase QT interval - for use When other arrhythmics fail
decrease the slope of phase 4 - increase PR interval (the AV node is particularly sensitive)
Giardiasis - Amoebic dysentery (E. histolytica) - Bacterial vaginitis (Gardnerella vaginalis) - Trichomonas

16. What is the most common cause of Pt noncompliance with Macrolides?
GI discomfort
Gemfibrozil - Clofibrate
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).
Pseudomonas species and Gram - rods

17. What is a common side effect of Misoprostol?
AZT - to reduce risk of Fetal Transmission
- Halothane - Valproic acid - acetaminophen - Amantia phalloides
Diarrhea
- Haloperidol - chlorpromazine - reserpine - MPTP

18. Name three K+ sparing diuretics?
GI side effects. (Indomethacin is less toxic - more commonly used.)
- Penicillin
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow
Spironolactone - Triamterene - Amiloride (the K+ STAys)

19. What is the MOA for Nystatin?
Oral treatment of superficial infections
Binds ergosterol - Disrupts fungal membranes
- B51Naloxone / naltrexone (Narcan)
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

20. What are four advantages of newer low - molecular - weight heparins (Enoxaparin)?
Similar to cyclosporine; binds to FK- binding protein - inhibiting secretion of IL-2 and other cytokines.
Gram + - Gram - - Norcardia - Chlamydia
1. Better bioavailability 2. 2 to 4 times longer half life 3. Can be administered subcutaneously 4. Does not require laboratory monitoring
- Phenytoin

21. List the specific antidote for this toxin: Warfarin
Onchocerciasis ('river blindness'-- rIVER- mectin)
compensatory tachycardia - fluid retention - lupus - like syndrome
- Vitamin K & fresh frozen plasma
sedation - depression - nasal stuffiness - diarrhea

22. What is the clinical use for Nystatin?
Binds to the Pyrophosphate Binding Site of the enzyme
Methylxanthine.
Topical and Oral - for Oral Candidiasis (Thrush)
1. Hypoglycemia (more common with 2nd - generation drugs: glyburide - glipizide) 2. Disulfiram - like effects (not seen with 2nd - generation drugs).

23. List the specific antidote for this toxin: Heparin
- Chloramphenicol
Intrathecally
Non - Nucleosides
- Protamine

24. Aztreonam is not ________ with penicillins
atropine - homatropine - tropicamide
cross - allergenic
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
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.

25. For Heparin What is the Route of administration
Indomethacin is used to close a patent ductus arteriosus.
Pseudomonas species and Gram - rods
Paranteral (IV - SC)
Botulinum

26. What is the MOA for Methicillin - Nafcillin - and Dicloxacillin?
Same as penicillin. Act as narrow spectrum antibiotics
Mg = Must go to the bathroom.
- Quinidine - quinine
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.

27. For Heparin What is the Duration of action
severe hypertension - CHF
Acute (hours)
- Vitamin K & fresh frozen plasma
Pituitary hormone.

28. Which diuretics increase urine Ca2+?
- Niacin - Ca++ channel blockers - adenosine - vancomycin
Botulinum
Amphetamine and Ephedrine
loop diuretics - spironolactone

29. What is the mechanism of action of Allopurinol used to treat chronic gout?
Zidovudine (AZT) - Didanosine (ddI) - Zalcitabine (ddC) - Stavudine (d4T) - Lamivudine (3TC)
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia
Digitoxin 168hrs Digoxin 40 hrs
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.

30. What is the clincial use for Misoprostol?
Acute gout.
1. Antiandrogen 2. Nausea 3. Vomiting
Ganciclovir is more toxic to host enzymes
Prevention of NSAID- induced peptic ulcers - maintains a PDA.

31. What is the memory key to remember Which pathway (extrinsic vs. intrinsic) and Which lab value Warfarin affects?
Leukotrienes increasing bronchial tone.
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.
Erectile dysfunction.
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.

32. Which drug(s) cause this reaction: P450 inhibition(6)?
Clavulanic acid
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide
- Cimetidine - ketoconazole - grapefruit juice - erythromycin - INH - sulfonamides
Hypersensitivity reactions

33. MOA: Block DNA topoisomerases
distal convoluted tubule (early)
Quinolones
Same as penicillin. Extended spectrum antibiotics
sedation - sleep alterations

34. What is a sign of toxicity with the use of thrombolytics?
Bleeding.
Buy AT 30 - CELL at 50'
block Na+ channels in the cortical collecting tubule
1. Antipyretic 2. Analgesic 3. Anti - inflammatory

35. What are the clinical uses for 3rd Generation Cephalosporins?
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)
torsade de pointes
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.

36. As an Anes you want to use a depolarizing neuromuscular blocking drug on your pt - What do you use
Penicillin - V
Succinylcholine
VACUUM your Bed Room'
Increase target cell response to insulin.

37. What process does Zafirlukast interfere with?
Bismuth and Amoxicillin or Tetracycline; against Helobacter pylori
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.
Leukotrienes increasing bronchial tone.
Gram + and Anerobes

38. How do you calculate maintenance dose?
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.
Lovastatin - Pravastatin - Simvastatin - Atorvastatin
Competitive inibitor of progestins at progesterone receptors.
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.

39. 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).
Milk or Antacids - because divalent cations inhibit Tetracycline absorption in the gut
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.
- Chlorpromazine - thioridazine - haloperidol

40. What is the mechanism of action of Omeprazole - Lansoprazole?
Irreversibly inhibits H+/K+ ATPase in stomach parietal cells.
fetal renal damage - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
NO AP duration effect. useful in V- tach that progresses to V- fib and in intractable SVT Last RESORT
Albuterol - tertbutaline

41. What side effect of using atropine to induce pupillary dilation would you expect?
Atropine would also block the receptors in the ciliary muscle - causing an impairment in accommodation (cycloplegia).
Beta Blockers
Inhibits formation of Initiation Complex - causes misreading of mRNA - Bactericidal
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.

42. MOA: Bactericidal antibiotics
- Deferoxamine
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
- Estrogen receptor antagonist - Breast CA - increased endometrial CA risk
Penicillin - Cephalosporins - Vancomycin - Aminoglycosides - Fluoroquinolones - Metronidazole

43. What are toxic side effects for Metronidazole?
Stimulates beta adrenergic receptors
Disulfiram - like reaction with EtOH - Headache
- Steroids - Tamoxifen
- Cimetidine - ketoconazole - grapefruit juice - erythromycin - INH - sulfonamides

44. What are two Glitazones?
1. Pioglitazone 2. Rosiglitazone.
AZT - to reduce risk of Fetal Transmission
Digitoxin 70% Digoxin 20-40%
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.

45. Ca2+ channel blockers - site of action?
Cell membrane Ca2+ channels of cardiac sarcomere
- Infections - Trauma - Seizures - CO - Overdose - Metabolic - Alcohol (IT'S COMA)
Disulfiram - like reaction with EtOH - Headache
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs

46. List the mechanism - clinical use - & toxicity of Prednisone.

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47. How can Vancomycin - induced 'Red Man Syndrome' be prevented?
sedation - sleep alterations
distal convoluted tubule (early)
Pretreat with antihistamines and a slow infusion rate
Blocks Norepi - but not Dopamine

48. What drug is used to treat Trematode/fluke (e.g. - Schistosomes - Paragonimus - Clonorchis) or Cysticercosis
Praziquantel
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow
Intrathecally
GI discomfort - Acute cholestatic hepatitis - Eosinophilia - Skin rashes

49. What are four conditions in Which H2 Blockers are used clinically?
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
Epinephrine to treat anaphylaxis. Also useful if you have open angle glaucoma - asthma - or hypotension.

50. What are the clinical uses for Imipenem/cilastatin?
K+ wasting - metabolic alkalosis - hypotension - ototoxicity
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.
Gram + cocci - Gram - rods - and Anerobes
Dopamine