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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. What is the major toxic side effect of Penicillin?
Hypersensitivity reactions
- Glucocorticoid withdrawal
Diarrhea
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.

2. Is resistant to penicillinase?
Verapamil - Diltiazem - Bepridil
- Penicillamine
Bacitracin - Vancomycin
Imipenem

3. ACE inhibitors - mechanism?
- Clindamycin
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic
Used in combination therapy with SMZ to sequentially block folate synthesis
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased

4. What conditions are treated with Metronidazole?
Giardiasis - Amoebic dysentery (E. histolytica) - Bacterial vaginitis (Gardnerella vaginalis) - Trichomonas
Lipoxygenase
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic

5. A common side effects of Interferon (INF) treatment is?
- Alkalates DNA - CML - Pulmonary fibrosis hyperpigmentation
physostigmine
Neutropenia
It affects beta receptors equally and is used in AV heart block (rare).

6. 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.
-100% oxygen - hyperbaric
- ED 50 is less than the Km (less than 50% of receptors)
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval

7. What is the category - desired effect - and possible mechanism of Theophylline in treating Asthma?
Methylzanthine; desired effect is bronchodilation - may cause bronchodilation by inhibiting phosphodiesterase - enzyme involved in degrading cAMP (controversial).
Erythromycin - Azithromycin - Clarithromycin
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)
- Upper respiratory tract infections - pneumonias - STDs: Gram+ cocci (streptococcal infect in pts allergic to penicillin) - Mycoplasma - Legionella - Chlamydia - Neisseria

8. What is the MOA of Polymyxins?
1. Antiandrogen 2. Nausea 3. Vomiting
Prophylaxis for Influenza A - Rubella; Parkinson's disease
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents

9. What is the formula for Clearance (CL)
Butyrophenone (neuroleptic).
CL= (rate of elimination of drug/ Plasma drug conc.)
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.
Spironolactone - Triamterene - Amiloride (the K+ STAys)

10. Why are Methicillin - Nafcillin - and Dicloxacillin penicillinase resistant?
Premature infants - because they lack UDP- glucuronyl transferase
- NaHCO3
Due to the presence of a bulkier R group
Chronic anticoagulation.

11. List the mechanism - clinical use - & toxicity of Paclitaxel.
1. Addison's disease 2. Inflammation 3. Immune suppression 4. Asthma
- Lithium
Enterobacter
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.

12. What are the nondepolarizing neuromuscular blocking drugs?
Tubocurarine - atracurium - mivacurium - pancuronium - vecuronium - rapacuronium
1. Meningococcal carrier state 2. Chemoprophylaxis in contacts of children with H. influenzae type B
Only in limited amounts
When pts have Low CD4+ (< 500 cells/cubic mm) or a High Viral Load

13. What is the clinical utility of clonidine?
1. Hypoglycemia (more common with 2nd - generation drugs: glyburide - glipizide) 2. Disulfiram - like effects (not seen with 2nd - generation drugs).
Treatment of hypertension - especially with renal disease (lowers bp centrally - so flow is maintained to kidney).
Enterobacter
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)

14. What is the MOA for Acyclovir?
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions
Antileukotriene; blocks synthesis by lipoxygenase.
Depolymerizes microtubules - impairing leukocyte chemotaxis and degranulation.
Inhibit viral DNA polymerase

15. Why is reserpine effective in treating HTN?
Reserpine inhibits dopamine transport into vesicles - attenuating its conversion to NE by dopamine beta - hydroxylase.
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.
Cephalosporins
Pseudomembranous colitis (C. difficile) - fever - diarrhea

16. Which drug(s) cause this reaction: Fanconi's syndrome?
Rifampin
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.
- Tetracycline
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.

17. List the specific antidote for this toxin: Anticholinesterases (organophosphate.)
- Atropine & pralidoxime
Inhibits Viral DNA polymerase
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.
- partial agonist can have increased - decreased - /A21or equal potency as full agonist. - Potency is an independent factor.

18. Adenosine - clinical use?
Benzodiazepine.
first dose orthostatic hypotension - dizziness - headache
Antileukotriene; blocks leukotriene receptors.
DOC in diagnosing and abolishing AV nodal arrhythmias

19. Ibutilide - toxicity?
amphetamine and ephedrine
Immediate anticoagulation for PE - stroke - angina - MI - DVT.
- Triggers apoptosis - CLL - Hodgkin's in MOPP - Cushing - like syndrome
torsade de pointes

20. Furosemide increases the excretion of What ion?
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
Gram + cocci - Haemophilus influenza - Enterobacter aerogenes - Neisseria species - P. mirabilis - E. coli - K. pneumoniae - Serratia marcescens ( HEN PEcKS )
Ca2+ (Loops Lose calcium)
Captopril - Enalapril - Lisinopril

21. What is the mechanism of action of Allopurinol used to treat chronic gout?
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.
- Ethosuxamide - sulfonamides - lamotrigine
- Glucocorticoid withdrawal
Aminoglycosides

22. What drug is used to treat Trematode/fluke (e.g. - Schistosomes - Paragonimus - Clonorchis) or Cysticercosis
- aminoglycosides - loop diuretics - cisplatin
- polymyxins
Praziquantel
hypertension - CHF - diabetic renal disease

23. What is the mecanism of action of the COX-2 inhibitors (celecoxib - rofecoxib)?
Ceftriaxone
Aminoglycosides
Inhibits CMV DNA polymerase
Selectively inhibit cyclooxygenase (COX) isoform 2 - Which is found in inflammatory cells nad mediates inflammation and pain; spares COX-1 Which helps maintain the gastric mucosa.

24. What is the category of drug names ending in - barbital (e.g. Phenobarbital)
AmOxicillin has greater Oral bioavailability
Digoxin=urinary Digitoxin=biliary
competitive inhibirot of aldosterone in the cortical collecting tubule
Babiturate.

25. MOA for Penicillin (3 answers)?
Blastomyces - Coccidioides - Histoplasma - C. albicans; Hypercortisolism
Antifungal.
1)Binds penicillin - binding proteins 2) Blocks transpeptidase cross - linking of cell wall 3) Activates autolytic enzymes
Suramin

26. Antiarrhythmic class IC- effects?
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine
Nonspecific beta - agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Adverse effect is tachycardia (Beta 1).
NO AP duration effect. useful in V- tach that progresses to V- fib and in intractable SVT Last RESORT

27. How does botulinum toxin result in respiratory arrest?
Potent immunosuppressive used in organ transplant recipients.
NO HYPERURICEMIA - NO SULFA AllERGY; same as furosemide otherwise
Prevents the release of ACh - Which results in muscle paralysis.
Oxygen

28. Which drug(s) cause this reaction: Photosensitivity(3)?
Hemicholinium inhibits the transport of choline into the nerve - thus inhibiting formation of ACh.
- Chloramphenicol
Digitoxin>95% Digoxin 75%
- Tetracycline - amiodarone - sulfonamides

29. What is the MOA of Ganciclovir?
Inhibits CMV DNA polymerase
- Shifts the curve to the right - increases Km
- Atropine & pralidoxime
- A57Blue lines in gingiva & long bones - Encephalopathy & Foot drop - Abdominal colic / - Sideroblastic anemia

30. What is the MOA for Vancomycin?
Inhibits cell wall mucopeptide formation - Bactericidal
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium
GI distress - Skin rash - and Seizures at high plasma levels
Prevents the release of Ca from SR of skeletal muscle

31. Name four HMG- CoA reductase inhibitors.
Lovastatin - Pravastatin - Simvastatin - Atorvastatin
Corticosteroids; prevent production of leukotrienes from arachodonic acid by blocking phospholipase A2. Drugs of choice in a patient with status asthmaticus (in combination with albuterol.)
Interstitial nephritis
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis

32. How are Sulfonamides employed clinically?
Amphetamine and Ephedrine
No - warfarin - unlike heparin - can cross the placenta.
Gram + - Gram - - Norcardia - Chlamydia
Methylxanthine.

33. Mannitol - contraindications?
- Chloramphenicol - benzene - NSAIDS - PTU - phenytoin
AZT - to reduce risk of Fetal Transmission
anuria - CHF
No - warfarin - unlike heparin - can cross the placenta.

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

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35. What are the major toxic side effects of the Cephalosporins?
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.
1) Hypersensitivity reactions 2) Increased nephrotoxicity of Aminoglycosides 3) Disulfiram - like reaction with ethanol (those with a methylthiotetrazole group - e.g. - cefamandole)
Prevents release of mediators from mast cells. Effective only for the prophylaxis of asthma. Not effective during an acute attack.
Staphlococcus aureus

36. Name three K+ sparing diuretics?
carbonic anhydrase inhibitors - K+ sparing diuretics
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
Spironolactone - Triamterene - Amiloride (the K+ STAys)
Inhibit RT of HIV and prevent the incorporation of viral genome into the host DNA

37. Which of epi - norepi - or isoproterenol results in bradycardia?
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.
Norepinephrine
Methicillin - Nafcillin - and Dicloxacillin
- Corticosteroids - heparin

38. What microorganisms is Aztreonam not effective against?
Gram + and Anerobes
Acts as a wide spectrum carbapenem
proarrhythmic
- Chloramphenicol

39. Furosemide - class and mechanism?
cortical collecting tubule
TCA
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.
Wide spectrum of systemic mycoses: Cryptococcus - Blastomyces - Coccidioides - Aspergillus - Histoplasma - Candida - Mucor

40. Adverse effects of Hydrochlorothiazide?
hypokalemia - slight hyperlipidemia - hyperuricemia - lassitude - hypercalcemia - hyperglycemia
- ACE inhibitors (Losartan>no cough)
troponin - tropomyosin system
Tricyclic antidepressant.

41. How are the Latent Hypnozoite (Liver) forms of Malaria (P. vivax - P.ovale) treated?
Primaquine
alpha -1 > alpha -2; used as a pupil dilator - vasoconstrictor - and for nasal decongestion
Saquinavir - Ritonavir - Indinavir - Nelfinavir
Pyridoxine (B6) administration

42. What anticholinesterase crosses the blood - brain - barrier?
Indirect agonist - uptake inhibitor
proximal convoluted tubule
physostigmine
Vibrio cholerae Acne Chlamydia Ureaplasma Urealyticum Mycoplasma pneumoniae Borrelia burgdorferi (Lyme's) Rickettsia Tularemia

43. Foscarnet toxicity?
Nephrotoxicity
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.
Inhibition of 50S peptidyl transferase - Bacteriostatic
Lidocaine - Mexiletine - Tocainide

44. What are five toxicities associated with Tacrolimus (FK506)?
Megaloblastic anemia - Leukopenia - Granulocytopenia
Protamine sulfate
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels

45. What is clinical use for Carbenicillin - Piperacillin - and Ticarcillin?
Pseudomonas species and Gram - rods
Prevents the release of Ca from SR of skeletal muscle
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
Useful in muscle paralysis during surgery or mechanical ventilation.

46. Name three ACE inhibitors?
VACUUM your Bed Room'
Alpha -1 antagonist
Cilastatin
Captopril - Enalapril - Lisinopril

47. Hydrochlorothiazide - toxicity? (hyperGLUC - plus others)
Ataxia - Dizziness - Slurred speech
Inhibits cell wall synthesis ( binds to PBP3). A monobactam
Hypokalemic metabolic alkalosis - hyponatremia - hyperGlycemia - hyperLipidemia - hyperUricemia - hyperCalcemia - sulfa allergy.
1. Antipyretic 2. Analgesic 3. Anti - inflammatory

48. Digoxin v. Digitoxin: half life?
Because they require some residual islet function.
Digitoxin 168hrs Digoxin 40 hrs
Modification via Acetylation
YES

49. What beta 2 agonist will help your 21yo Astma pt?
Neostigmine - pyridostigmine edrophonium - physostigmine echothiophate
Useful in muscle paralysis during surgery or mechanical ventilation.
K+ wasting - metabolic alkalosis - hypotension - ototoxicity
Albuterol - tertbutaline

50. What should not be taken with Tetracyclines? / Why?
Pseudomembranous colitis (C. difficile) - fever - diarrhea
Milk or Antacids - because divalent cations inhibit Tetracycline absorption in the gut
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.
Modification via Acetylation