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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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1. What is Clindamycin used for clinically?
penicillinase resistant
Increase target cell response to insulin.
Anaerobic infections (e.g. - B. fragilis - C. perfringens)
- Methylene blue

2. Adverse effects of Clonidine?
- Aminocaproic acid
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.
Penicillin - G
dry mouth - sedation - severe rebound hypertension

3. What is the clinical use for Warfarin?
Cryptococcal meningitis in AIDS patients and Candidal infections of all types
Premature infants - because they lack UDP- glucuronyl transferase
Chronic anticoagulation.
GI intolerance (nausea - diarrhea) - Hyperglycemia - Lipid abnormalities - Thrombocytopenia (Indinavir)

4. Name two organisms Vancomycin is commonly used for?
Activates cholinergic receptors on bladder and bowel smooth muscle - alleviating post - op and neurogenic ileus and urinary retention.
Increase target cell response to insulin.
Lipoxygenase
Staphlococcus aureus and Clostridium difficile (pseudomembranous colitis)

5. What is the major toxic side effect of Penicillin?
Diarrhea
Rifampin
AmOxicillin has greater Oral bioavailability
Hypersensitivity reactions

6. How do spare receptors effect the Km?
- ED 50 is less than the Km (less than 50% of receptors)
Inhibit viral DNA polymerase
Constant FRACTION eliminated per unit time.(exponential)
Useful in muscle paralysis during surgery or mechanical ventilation.

7. Which drug(s) cause this reaction: Agranulocytosis (3)?
- Clindamycin
Beta1 more than B2
Gram + cocci - Gram - rods - and Anerobes
- Cloazapine - carbamazapine - colchicine - PTU

8. What is the mechanism of action of the Sulfonylureas?
Fever/Chills - Hypotension - Nephrotoxicity - Arrhythmias
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.
- Chloramphenicol - benzene - NSAIDS - PTU - phenytoin
- aminoglycosides - loop diuretics - cisplatin

9. What is the memory key involving the '4 R's of Rifampin?'
- Haloperidol - chlorpromazine - reserpine - MPTP
Polymyxin B - Polymyxin E
- Upper respiratory tract infections - pneumonias - STDs: Gram+ cocci (streptococcal infect in pts allergic to penicillin) - Mycoplasma - Legionella - Chlamydia - Neisseria
1. RNA pol inhibitor 2. Revs up P450 3. Red/orange body fluids 4. Rapid resistance if used alone

10. What is the major side effect for Ampicillin and Amoxicillin?
Cryptococcal meningitis in AIDS patients and Candidal infections of all types
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis
Hypersensitivity reactions
1. Antipyretic 2. Analgesic 3. Anti - inflammatory

11. If a patient is given hexamethonium - What would happen to his/her heart rate?
Bethanechol - Neostigmine - physostigmine
Paranteral (IV - SC)
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.
These B-2 agonists cause respiratory smooth muscle to relax.

12. What enzymes are inhibited by NSAIDs - acetaminophen and COX II inhibitors?
- Constant AMOUNT eliminated per unit time. - Etoh & ASA
Blocks Influenza A and RubellA; causes problems with the cerebellA
GI upset
Cyclooxygenases (COX I - COX II).

13. Resistance mechanisms for Macrolides

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14. What is combination TMP- SMZ used to treat?
- Cloazapine - carbamazapine - colchicine - PTU
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia
Diarrhea
GI distress - Tooth discoloration and Inhibition of bone growth in children - Fanconi's syndrome - Photosensitivity

15. Digitalis - site of action?
Suramin
- EDTA - dimercaprol - succimer - & penicillamine
Na/K ATPase
sedation - positive Coombs' test

16. What are three possible toxicities of NSAID usage?
effective in torsade de pointes and digoxin toxicity
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents
1. Renal damage 2. Aplastic anemia 3. GI distress
Triple Therapy' 2 Nucleoside RT Inhibitors with a Protease Inhibitor

17. Antiarrhythmic class IB- toxicity?
Increase target cell response to insulin.
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents
local anesthetic. CNS stimulation or depression. CV depression.
- B51Naloxone / naltrexone (Narcan)

18. What is the MOA for Methicillin - Nafcillin - and Dicloxacillin?
NO HYPERURICEMIA - NO SULFA AllERGY; same as furosemide otherwise
Sucralfate cannot work in the presence of antacids or H2 blockers because it requires an acidic environment to polymerize.
Same as penicillin. Act as narrow spectrum antibiotics
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased

19. What class of drug is echothiophate? What is its indication?
- Shifts the curve to the right - increases Km
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.
Quinolones
anticholinesterase glaucoma

20. What is the effect of the Glitazones in diabetes treatment?
Increase target cell response to insulin.
- S- phase anti - metabolite folate analogue - Luk - Lymp - sarc - RA - & psoriasis / - Reversible myelosuppression
RESPIre
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic

21. For Heparin What is the Duration of action
Quinidine - Amiodarone - Procainamide - Disopyramide
Acute (hours)
TMP- SMZ (DOC) - aerosolized pentamidine
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.

22. Which diuretics decrease urine Ca2+?
Flutamide is a nonsteroidal competitive inhibitor of androgens at the testosterone receptor - used in prostate carcinoma.
loop diuretics - spironolactone
Digitoxin 168hrs Digoxin 40 hrs
thiazides - amiloride

23. Which drug(s) cause this reaction: Osteoporosis (2)?
- Corticosteroids - heparin
Forms toxic metabolites in the bacterial cell - Bactericidal
fetal renal toxicity - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.

24. What is the formula for Volume of distribution (Vd)
Short.
Vd= (Amt. of drug in body/ Plasma drug conc.)
Methicillin - Nafcillin - and Dicloxacillin
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis

25. What type of patient should not take Misoprostol and why?
Hemicholinium inhibits the transport of choline into the nerve - thus inhibiting formation of ACh.
Misoprostol is contraindicated in women of childbearing potential because it is an abortifacient.
- reduction - oxy - & hydrolysis - H2O sol. Polar product - P450
Inhibit DNA Gyrase (topoisomerase II) - Bactericidal

26. What is the category - desired effect - and possible mechanism of Theophylline in treating Asthma?
Rash - Pseudomembranous colitis
Decreased uptake or Increased transport out of cell
Methylzanthine; desired effect is bronchodilation - may cause bronchodilation by inhibiting phosphodiesterase - enzyme involved in degrading cAMP (controversial).
Gram - rods: Klebsiella species - Pseudomonas species - Serratia species

27. What additional side effects exist for Ampicillin?
Inhibt Assembly of new virus by Blocking Protease Enzyme
Chronic gout.
Rash - Pseudomembranous colitis
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic

28. Antimicrobial prophylaxis for Syphilis
Stimulates beta adrenergic receptors
Benzathine penicillin G
- Shifts the curve down - reduces Vmax
Sucralfate cannot work in the presence of antacids or H2 blockers because it requires an acidic environment to polymerize.

29. How does a noncompetitive antagonist effect an agonist?
- Shifts the curve down - reduces Vmax
severe hypertension - CHF
Fever/Chills - Hypotension - Nephrotoxicity - Arrhythmias
SLUD (salivation - Lacrimation - urination - Defecation)as well as airway secretion - GI motility - acid secretions

30. Antiarrhythmic Class III- effects?
Bacitracin - Vancomycin
HSV - VZV - EBV - Mucocutaneous and Genital Herpes Lesions - Prophylaxis in Immunocompromised pts
- ACE inhibitors (Losartan>no cough)
increase AP duration - increase ERP - increase QT interval - for use When other arrhythmics fail

31. Resistance mechanisms for Sulfonamides
Hormone synthesis inhibition (Gynecomastia) - Liver dysfunction (Inhibits CYP450) - Fever - Chills
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis
Primaquine

32. Reserpine will block the syntheis of this drug and but not its precursor.
Blocks Norepi - but not Dopamine
AV nodal cells
1. Antipyretic 2. Analgesic 3. Anti - inflammatory 4. Antiplatelet drug.
Ca2+ (Loops Lose calcium)

33. What enzyme is responsible for the breakdown of ACh in the synaptic cleft?
- Fluoroquinolones
Acetylcholinesterase; ACh is broken down into choline and acetate.
Hemicholinium inhibits the transport of choline into the nerve - thus inhibiting formation of ACh.
Cephalosporins

34. What are Amantadine - associated side effects?
1. Antipyretic 2. Analgesic 3. Anti - inflammatory 4. Antiplatelet drug.
Digitoxin 70% Digoxin 20-40%
Norepinephrine
Ataxia - Dizziness - Slurred speech

35. Why would dopamine be useful in treating shock?
Receptors = D1=D2>beta>alpha - thus increasing heart rate (beta) and blood pressure (alpha vasoconstriction) while maintaining kidney perfusion (dopamine receptors)
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
severe orthostatic hypotension - blurred vision - constipation - sexual dysfunction

36. How is Vancomycin used clinically?
For serious - Gram + multidrug - resistant organisms
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.
Methylzanthine; desired effect is bronchodilation - may cause bronchodilation by inhibiting phosphodiesterase - enzyme involved in degrading cAMP (controversial).
Tubocurarine - atracurium - mivacurium - pancuronium - vecuronium - rapacuronium

37. Cocaine shares is mechanism of action with What antidepressant
Gentamicin - Neomycin - Amikacin - Tobramycin - Streptomycin
TCA
It inhibits release of NE.
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol

38. What is the most common cause of Pt noncompliance with Macrolides?
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
GI discomfort
Blocking muscarinic receptors in the circular fibers of the eye - results in unopposed action of radial muscles to dilate.
Mg = Must go to the bathroom.

39. Aztreonam is not usually...
Well tolerated in general but occasionally - Nephrotoxicity - Ototoxicity - Thrombophlebitis - diffuse flushing='Red Man Syndrome'
Blocks viral penetration/uncoating; may act to buffer the pH of the endosome
toxic
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs

40. Furosemide - clinical use?
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia
hypertension - CHF - diabetic renal disease
Imipenem
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions

41. What is a sign of toxicity with the use of thrombolytics?
Bleeding.
Cardiac glycoside (inotropic agent).
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.)
Penicillin - V

42. Which diuretics cause alkalosis?
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.
CL= (rate of elimination of drug/ Plasma drug conc.)
- DNA intercalator - Hodgkin's - myeloma - sarcoma - and solid tumors - Cardiotoxicity & alopecia
loop diuretics - thiazides

43. What sympathomimetic would you not prescribe for hypotension in a pt with renal artery sclerosis.
- Physostigmine salicylate
pulmonary edema - dehydration
Norepinephrine (Alpha1 -2 and beta 1)
Penicillin - Ampicillin - Ticarcillin - Pipercillin - Imipenem - Aztreonam - Cephalosporins

44. How is Amphotericin B used clinically?
Wide spectrum of systemic mycoses: Cryptococcus - Blastomyces - Coccidioides - Aspergillus - Histoplasma - Candida - Mucor
all except the K+ sparing diuretics Spironolactone - Triamterene - Amiloride
- ED 50 is less than the Km (less than 50% of receptors)
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow

45. What is the MOA of Amantadine?
- Daunorubicin & Doxorubicin
Beta -2 agonist.
Blocks viral penetration/uncoating; may act to buffer the pH of the endosome
Activates antithrombin III

46. Common toxicities associated with Fluoroquinolones?
- Protamine
hyperchloremic metabolic acidosis - neuropathy - NH3 toxicity - sulfa allergy
GI upset - Superinfections - Skin rashes - Headache - Dizziness
Foscarnet = pyroFosphate analog

47. Does Ampicillin or Amoxicillin have a greater oral bioavailability?
1. Pioglitazone 2. Rosiglitazone.
Onchocerciasis ('river blindness'-- rIVER- mectin)
1. Streptokinase 2. Urokinase 3. tPA (alteplase) - APSAC (anistreplase)
AmOxicillin has greater Oral bioavailability

48. Beta Blockers - BP?
decrease
hypertension - angina - arrhythmias
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine
Local anesthetic.

49. List the mechanism - clinical use - & toxicity of Paclitaxel.
Triple Therapy' 2 Nucleoside RT Inhibitors with a Protease Inhibitor
GET on the Metro
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.

50. Name common Polymyxins
Polymyxin B - Polymyxin E
CMV Retinitis in IC pts When Ganciclovir fails
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.
Aluminum sucrose sulfate polymerizes in the acid environment of the stomach and selectively binds necrotic peptic ulcer tissue. Acts as a barrier to acid - pepsin - and bile.