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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 are the clinical uses for Aztreonam?
Erectile dysfunction.
Gram - rods: Klebsiella species - Pseudomonas species - Serratia species
Inhibit steroid synthesis - used in the treatment of polycystic ovarian syndrome to prevent hirsutism.
- Vitamin K & fresh frozen plasma

2. How does a noncompetitive antagonist effect an agonist?
Epinephrine to treat anaphylaxis. Also useful if you have open angle glaucoma - asthma - or hypotension.
Those patients who are taking nitrates.
- DNA intercalator - Hodgkin's - myeloma - sarcoma - and solid tumors - Cardiotoxicity & alopecia
- Shifts the curve down - reduces Vmax

3. What is the major side effect for Carbenicillin - Piperacillin - and Ticarcillin?
Ld= (CpxVd)/F Cp=plasma conc. F= Bioaval.
Hypersensitivity reactions
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
orthostatic and exercise hypotension - sexual dysfunction - diarrhea

4. Antimicrobial prophylaxis for PCP
Cryptococcal meningitis in AIDS patients and Candidal infections of all types
TMP- SMZ (DOC) - aerosolized pentamidine
Long.
atropine - homatropine - tropicamide

5. What is the clinical use for Clomiphene?
It acts presynaptically to increase NE release.
Treatment of infertility.
Heparin catalyzes the activation of antithrombin III.
AZT - to reduce risk of Fetal Transmission

6. What antimuscarinic agent is used in asthma and COPD?
Sildenafil fills the penis
Ipratropium
Foscarnet = pyroFosphate analog
IV vitamin K and fresh frozen plasma

7. List the mechanism - clinical use - & toxicity of Nitrosureas.
Nonspecific beta - agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Adverse effect is tachycardia (Beta 1).
- Alkalate DNA - Brain tumors - CNS toxicity
Prophylaxis for Influenza A - Rubella; Parkinson's disease
Early myocardial infarction.

8. Ethacrynic Acid - clinical use?
Constant FRACTION eliminated per unit time.(exponential)
Diuresis in pateints with sulfa allergy
Nevirapine - Delavirdine
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.

9. Preferential action of the Ca2+ channel blockers at cardiac muscle?
Acute (hours)
- Tetracycline
cardiac muscle: Verapamil>Diltiazem>Nifedipine
1. Gastric ulceration 2. Bleeding 3. Hyperventilation 4. Reye's syndrome 5. Tinnitus (CN VIII)

10. What is the memory key for the effect of magnesium hydroxide overuse?
Inhibit Ergosterol synthesis
glaucoma - urinary alkalinization - metabolic alkalosis - altitude sickness
Mg = Must go to the bathroom.
Keratin containing tissues - e.g. - nails

11. What are three types of antacids and the problems that can result from their overuse?
Aminoglycosides - Tetracyclines
Digoxin=urinary Digitoxin=biliary
It must be Phosphorylated by Viral Thymidine Kinase
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia

12. What are common toxicities associated with Tetracyclines?

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13. What are the clinical indications for Azole therapy?
Ibuprofen - Naproxen - and Indomethacin
Diuresis in pateints with sulfa allergy
Systemic mycoses
It affects beta receptors equally and is used in AV heart block (rare).

14. Acetazolamide causes?

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15. What parasites are treated with Pyrantel Pamoate (more specific)?
Neutropenia (ticlopidine); reserved for those who cannot tolerate aspirin.
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
PT
Decreased uptake or Increased transport out of cell

16. What are Aminoglycosides synergistic with?
very short acting
Nevirapine - Delavirdine
Beta - lactam antibiotics
- Halothane - Valproic acid - acetaminophen - Amantia phalloides

17. Which diuretics cause alkalosis?
1) Chloramphenical = bacteriostatic 2) Erythromycin = bacteriostatic 3) Lincomycin = bacteriostatic 4)cLindamycin = bacteriostatic
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.
Doxycycline - because it is fecally eliminated
loop diuretics - thiazides

18. What are Methicillin - Nafcillin - and Dicloxacillin used for clinically?
Staphlococcus aureus
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels
- Ammonium Chloride
- Tetracycline - amiodarone - sulfonamides

19. Adverse effects of Prazosin?
first dose orthostatic hypotension - dizziness - headache
Vibrio cholerae Acne Chlamydia Ureaplasma Urealyticum Mycoplasma pneumoniae Borrelia burgdorferi (Lyme's) Rickettsia Tularemia
CMV Retinitis in IC pts When Ganciclovir fails
Leukotrienes increasing bronchial tone.

20. How is Ganciclovir used clinically?
decrease conduction velocity - increase ERP - increase PR interval
Inhibit DNA Gyrase (topoisomerase II) - Bactericidal
CMV - esp in Immunocompromised patients
- Infections - Trauma - Seizures - CO - Overdose - Metabolic - Alcohol (IT'S COMA)

21. What is Metronidazole used for clinically?
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.
Ototoxicity - Hypokalemia - Dehydration - Allergy (sulfa) - Nephritis (interstitial) - Gout
Potent immunosuppressive used in organ transplant recipients.
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium

22. Sotalol - toxicity?
- aminoglycosides - loop diuretics - cisplatin
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents
Can affect absorption - bioavailability - or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying.
torsade de pointes - excessive Beta block

23. List the specific antidote for this toxin: Warfarin
- Vitamin K & fresh frozen plasma
- Tetracycline
- Phenytoin
Epinephirine(Alpha1 -2 and Beta 1 -2)

24. What is a sign of toxicity with the use of thrombolytics?
Bleeding.
Hexamethonium is a nicotinic antagonist - and thus is a ganglionic blocker.
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic
- Normalize K+ - Lidocaine - & Anti - dig Mab

25. What is the clinical use of Mifepristone (RU486)?
Tricyclic antidepressant.
Abortifacient.
1. Antipyretic 2. Analgesic 3. Anti - inflammatory
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic

26. Name the common Aminoglycosides (5)
Gentamicin - Neomycin - Amikacin - Tobramycin - Streptomycin
Inhibit viral DNA polymerase
Rifampin (DOC) - minocycline
Yes

27. List the mechanism - clinical use - & toxicity of Tamoxifen.
Buy AT 30 - CELL at 50'
Pseudomonas species and Gram - rods
- Estrogen receptor antagonist - Breast CA - increased endometrial CA risk
Keratin containing tissues - e.g. - nails

28. What is the category - desired effect - and possible mechanism of Theophylline in treating Asthma?
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens
decrease conduction velocity - increase ERP - increase PR interval
Methylzanthine; desired effect is bronchodilation - may cause bronchodilation by inhibiting phosphodiesterase - enzyme involved in degrading cAMP (controversial).
- Act on same receptor - Full has greater efficacy

29. Triamterene and amiloride - mechanism?
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.
sedation - positive Coombs' test
block Na+ channels in the cortical collecting tubule
- Disulfram & also sulfonylureas - metronidazole

30. How can Vancomycin - induced 'Red Man Syndrome' be prevented?
Pretreat with antihistamines and a slow infusion rate
Hypersensitivity reactions
Useful in muscle paralysis during surgery or mechanical ventilation.
proximal convoluted tubule - thin descending limb - and collecting duct

31. What are two indirect acting adrenergic agonists?
amphetamine and ephedrine
thick ascending limb
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens
AZT

32. What are three possible toxicities of NSAID usage?
check PFTs - LFTs - and TFTs
Protease inhibitor.
1. Renal damage 2. Aplastic anemia 3. GI distress
hypertension - angina - arrhythmias

33. K+ sparing diuretics - site of action?
Neutropenia
cortical collecting tubule
physostigmine
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.

34. Why does NE result in bradycardia?
Long.
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic
penicillinase resistant

35. K+- clinical use?
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors
- Physostigmine salicylate
depresses ectopic pacemakers - especially in digoxin toxicity
- Glucocorticoid withdrawal

36. Why is pyridostigmine effective in the treatment of myasthenia gravis?
- Chloramphenicol - benzene - NSAIDS - PTU - phenytoin
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.
Antibiotic - protein synthesis inhibitor.
As an anticholinesterase it increases endogenous ACh and thus increases strength.

37. What is the category - desired effect - and adverse effect of Isoproterenol in the treatment of Asthma?
Activates antithrombin III
Nonspecific beta - agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Adverse effect is tachycardia (Beta 1).
Binds to the Pyrophosphate Binding Site of the enzyme
decrease

38. Which antimicrobials inhibit protein synthesis at the 50S subunit? (4)
- Constant AMOUNT eliminated per unit time. - Etoh & ASA
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.
BM suppression (neutropenia - anemia) - Peripheral neuropathy
1) Chloramphenical = bacteriostatic 2) Erythromycin = bacteriostatic 3) Lincomycin = bacteriostatic 4)cLindamycin = bacteriostatic

39. How is Trimethoprim used clinically?
TMP- SMZ
Tricyclic antidepressant.
Penicillin - Cephalosporins - Vancomycin - Aminoglycosides - Fluoroquinolones - Metronidazole
Used in combination therapy with SMZ to sequentially block folate synthesis

40. Which receptors does phenylephrine act upon?
ACE inhibitor.
- Hydralazine - Procainamide - INH - phenytoin
Increased systolic and pulse pressure - decreased diastolic pressure - and little change in mean pressure.
alpha -1 > alpha -2; used as a pupil dilator - vasoconstrictor - and for nasal decongestion

41. Explain differences between full and partial agonists(2).
Binds to the Pyrophosphate Binding Site of the enzyme
- Act on same receptor - Full has greater efficacy
Cell membrane Ca2+ channels of cardiac sarcomere
Peptic ulcer disease.

42. How do you treat coma in the ER (4)?
Beta1 more than B2
Protamine sulfate
- Airway - Breathing - Circulation - Dextrose (thiamine & narcan) - ABCD
Imipenem

43. Mannitol - site of action?
proximal convoluted tubule - thin descending limb - and collecting duct
- Hypersensitivity reactions - Hemolysis - Nephrotoxicity (tubulointerstitial nephritis) - Kernicterus in infants Displace other drugs from albumin (e.g. - warfarin)
Nitrates
IV vitamin K and fresh frozen plasma

44. Guanethidine enhances the release of Norepi?
Albuterol - tertbutaline
Benzathine penicillin G
No
No - it inhibits the release of Nor Epi

45. What are Fluoroquinolones indicated for? (3)
1.Gram - rods of the Urinary and GI tracts (including Pseudomonas) 2.Neisseria 3. Some Gram + organisms
Diuresis in pateints with sulfa allergy
proximal convoluted tubule - thin descending limb - and collecting duct
decrease conduction velocity - increase ERP - increase PR interval

46. Which drug(s) cause this reaction: G6PD hemolysis(8)?
Anaerobic infections (e.g. - B. fragilis - C. perfringens)
Indomethacin is used to close a patent ductus arteriosus.
Neostigmine - pyridostigmine edrophonium - physostigmine echothiophate
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol

47. Which drug(s) cause this reaction: Atropine - like side effects?
Hypersensitivity reactions
Acetylcholinesterase; ACh is broken down into choline and acetate.
1. Antipyretic 2. Analgesic 3. Anti - inflammatory
- Tricyclic antidepressants

48. MOA: Block protein synthesis at 50s subunit
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
GI disturbances.
- Normalize K+ - Lidocaine - & Anti - dig Mab
Beta -2 agonist.

49. Which drug(s) cause this reaction: Aplastic anemia (5)?
- Chloramphenicol - benzene - NSAIDS - PTU - phenytoin
blocks SR Ca2+ channels
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).
Malaria (P. falciparum)

50. These drugs acts indirectly by releasing strored catecholamines in the presynaptic terminal
TMP- SMZ (DOC) - aerosolized pentamidine
Verapamil - Diltiazem - Bepridil
CL= (rate of elimination of drug/ Plasma drug conc.)
Amphetamine and Ephedrine