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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 beta 2 agonist will help your 21yo Astma pt?
Acute gout.
- Metronidazole - certain cephalosporins - procarbazine - sulfonylureas
Albuterol - tertbutaline
Hypersensitivity reactions

2. What is the MOA for the Macrolides?
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic
Large anionic polymer - acidic
Cryptococcal meningitis in AIDS patients and Candidal infections of all types

3. What is Niclosamide used for?
- B51Naloxone / naltrexone (Narcan)
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis
Ganciclovir is more toxic to host enzymes
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol

4. What are Fluoroquinolones indicated for? (3)
Acetylcholinesterase; ACh is broken down into choline and acetate.
Prevents the release of Ca from SR of skeletal muscle
1.Gram - rods of the Urinary and GI tracts (including Pseudomonas) 2.Neisseria 3. Some Gram + organisms
The only local anesthetic with vasoconstrictive properties.

5. What is the mechanism of action of Omeprazole - Lansoprazole?
Irreversibly inhibits H+/K+ ATPase in stomach parietal cells.
Ca2+ (Loops Lose calcium)
Fever/Chills - Hypotension - Nephrotoxicity - Arrhythmias
Bethanechol - Neostigmine - physostigmine

6. How is Foscarnet used clinically?
impotence - asthma - CV effects (bradycardia - CHF - AV block) - CNS effects (sedation - sleep alterations)
CMV Retinitis in IC pts When Ganciclovir fails
Due to the presence of a bulkier R group
- Ammonium Chloride

7. What is the formula for Volume of distribution (Vd)
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids
Neutropenia (ticlopidine); reserved for those who cannot tolerate aspirin.
- Cloazapine - carbamazapine - colchicine - PTU
Vd= (Amt. of drug in body/ Plasma drug conc.)

8. What is the mechanism of Azathioprine?
Early myocardial infarction.
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
Antimetabolite derivative of 6- mercaptopurine that interferes with the metablolism and synthesis of nucleic acid.
- Chloramphenicol

9. List the mechanism - clinical use - & toxicity of 6 MP.
It affects beta receptors equally and is used in AV heart block (rare).
- inhibits HGPRT (pur. Syn.) - Luk - Lymph
GI discomfort - Acute cholestatic hepatitis - Eosinophilia - Skin rashes
1. Addison's disease 2. Inflammation 3. Immune suppression 4. Asthma

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

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11. Resistance mechanisms for Chloramphenicol
local anesthetic. CNS stimulation or depression. CV depression.
Modification via Acetylation
GI intolerance (nausea - diarrhea) - Hyperglycemia - Lipid abnormalities - Thrombocytopenia (Indinavir)
edrophonium (extremely short acting anticholinesterase)

12. What do Aminoglycosides require for uptake?
Ceftriaxone
1. Reliable (<1% failure) 2. Lowers risk of endometrial and ovarian cancer 3. Decreased incidence of ectopic pregnancy 4. Lower risk of pelvic infections 5. Regulation of menses
Oxygen
Nonspecific beta - agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Adverse effect is tachycardia (Beta 1).

13. Antiarrhythmic class II- mechanism?
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.
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.)
blocking the beta adrenergic receptor leads to decreased cAMP - and decreased Ca2+ flux
Extended spectrum penicillin: certain Gram + bacteria and Gram - rods

14. How do Sulfonamides act on bacteria?
Amphotericin B - Nystatin - Fluconazole/azoles
Only in limited amounts
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
decrease conduction velocity - increase ERP - increase PR interval

15. K+ sparing diuretics - clinical use?
Inhibits formation of Initiation Complex - causes misreading of mRNA - Bactericidal
severe hypertension - CHF
hyperaldosteronism - K+ depletion - CHF
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.

16. Name three Antiarrhythmic drugs in class IB.
Pseudomembranous colitis (C. difficile) - fever - diarrhea
Gram + cocci - Haemophilus influenza - Enterobacter aerogenes - Neisseria species - P. mirabilis - E. coli - K. pneumoniae - Serratia marcescens ( HEN PEcKS )
Lidocaine - Mexiletine - Tocainide
- Aminocaproic acid

17. What is a sign of toxicity with the use of thrombolytics?
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.
- Nitrate - hydroxocobalamin thiosulfate
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
Bleeding.

18. How is Amphotericin B used clinically?
- DNA intercalator - Hodgkin's - myeloma - sarcoma - and solid tumors - Cardiotoxicity & alopecia
Long.
Wide spectrum of systemic mycoses: Cryptococcus - Blastomyces - Coccidioides - Aspergillus - Histoplasma - Candida - Mucor
Rifampin

19. Common toxicities associated with Fluoroquinolones?
- Physostigmine salicylate
GI upset - Superinfections - Skin rashes - Headache - Dizziness
Blocks Influenza A and RubellA; causes problems with the cerebellA
Quinidine - Amiodarone - Procainamide - Disopyramide

20. What are four conditions in Which H2 Blockers are used clinically?
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome
Na/K ATPase
- polymyxins
Ipratropium

21. What are four clinical activities of Aspirin?
1. Antipyretic 2. Analgesic 3. Anti - inflammatory 4. Antiplatelet drug.
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.
INH: Injures Neurons and Hepatocytes
- DNA intercalator - Hodgkin's - myeloma - sarcoma - and solid tumors - Cardiotoxicity & alopecia

22. How does NE modulate its own release? What other neurotransmitter has this same effect?
post MI and digitalis induced arrhythmias
The PTT.
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.
Mycobacterium tuberculosis - the only agent used as solo prophylaxis against TB

23. What two vasodilators require simultaneous treatment with beta blockers to prevent reflex tachycardia and diuretics to prevent salt retention?
In treatment of malignant hyperthermia - due to concomitant use of halothane and succinylcholine. Also in neuroleptic malignant syndrome - a toxicity of antipsychotic drugs.
- EDTA - dimercaprol - succimer - & penicillamine
Hydralazine and Minoxidil
Epinephrine

24. What is the clinical use of Tacrolimus (FK506)?
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
Potent immunosuppressive used in organ transplant recipients.
Prevents the release of Ca from SR of skeletal muscle
GI intolerance (nausea - diarrhea) - Hyperglycemia - Lipid abnormalities - Thrombocytopenia (Indinavir)

25. What is the mechanism of action of Allopurinol used to treat chronic gout?
Buy AT 30 - CELL at 50'
In treatment of malignant hyperthermia - due to concomitant use of halothane and succinylcholine. Also in neuroleptic malignant syndrome - a toxicity of antipsychotic drugs.
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.
- Aminocaproic acid

26. What is the clinical use for Clomiphene?
Treatment of infertility.
Ataxia - Dizziness - Slurred speech
1.Gram - rods of the Urinary and GI tracts (including Pseudomonas) 2.Neisseria 3. Some Gram + organisms
Aplastic anemia (dose independent) - Gray Baby Syndrome

27. What is Metronidazole used for clinically?
Pseudomonas species and Gram - rods
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium
Depolymerizes microtubules - impairing leukocyte chemotaxis and degranulation.
1) Chloramphenical = bacteriostatic 2) Erythromycin = bacteriostatic 3) Lincomycin = bacteriostatic 4)cLindamycin = bacteriostatic

28. Adverse effects of Reserpine?
Ataxia - Dizziness - Slurred speech
Beta 2 agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Use during acute exacerbation.
GI discomfort - Acute cholestatic hepatitis - Eosinophilia - Skin rashes
sedation - depression - nasal stuffiness - diarrhea

29. What is the mechanism of action of Ticlopidine - Clopidogrel
- Glucagon
Inhibits reabsorption of uric acid.
Inhibit viral DNA polymerase
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.

30. K+- clinical use?
- Alkalinize urine & dialysis
depresses ectopic pacemakers - especially in digoxin toxicity
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity
1. Reliable (<1% failure) 2. Lowers risk of endometrial and ovarian cancer 3. Decreased incidence of ectopic pregnancy 4. Lower risk of pelvic infections 5. Regulation of menses

31. List the specific antidote for this toxin: Copper
impotence - asthma - CV effects (bradycardia - CHF - AV block) - CNS effects (sedation - sleep alterations)
- Penicillamine
Pentavalent Antimony
Nucleosides

32. List the specific antidote for this toxin: Carbon monoxide
1. Antiandrogen 2. Nausea 3. Vomiting
Hormone synthesis inhibition (Gynecomastia) - Liver dysfunction (Inhibits CYP450) - Fever - Chills
-100% oxygen - hyperbaric
Systemic mycoses

33. Bretyllium - toxicity?
post MI and digitalis induced arrhythmias
new arrhythmias - hypotension
- Flumazenil
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids

34. Acetazolamide - mechanism?
Nevirapine - Delavirdine
Lidocaine - Mexiletine - Tocainide
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.
local anesthetic. CNS stimulation or depression. CV depression.

35. Ethacrynic Acid - toxicity?
Increase target cell response to insulin.
NO HYPERURICEMIA - NO SULFA AllERGY; same as furosemide otherwise
Imipenem
1. Predisposes to viral infections and lymphoma 2. Nephrotoxic (preventable with mannitol diuresis)

36. Spironolactone - mechanism?
competitive inhibirot of aldosterone in the cortical collecting tubule
To inhibit renal Dihydropeptidase I and decrease Imipenem inactivation in the renal tubules
TMP- SMZ (DOC) - aerosolized pentamidine
Does not cross

37. Decrease Digitoxin dose in renal failure?
- EDTA - dimercaprol - succimer - & penicillamine
is resistant
AV nodal cells
NO

38. What are are the Sulfonylureas (general description) and What is their use?
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
No - hemicholinum block the uptake of Choline and thus Ach synthesis
1. Meningococcal carrier state 2. Chemoprophylaxis in contacts of children with H. influenzae type B
- Estrogen receptor antagonist - Breast CA - increased endometrial CA risk

39. What should not be taken with Tetracyclines? / Why?
Non - Nucleosides
- Upper respiratory tract infections - pneumonias - STDs: Gram+ cocci (streptococcal infect in pts allergic to penicillin) - Mycoplasma - Legionella - Chlamydia - Neisseria
Hemicholinium inhibits the transport of choline into the nerve - thus inhibiting formation of ACh.
Milk or Antacids - because divalent cations inhibit Tetracycline absorption in the gut

40. What is the MOA for Vancomycin?
Inhibits cell wall mucopeptide formation - Bactericidal
Ciprofloxacin - Norfloxacin - Ofloxacin - Grepafloxacin - Enoxacin - Nalidixic acid
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
Leukotrienes increasing bronchial tone.

41. What patients are at risk for life threatening hypotension When taking Sildenafil (Viagra)?
Tricyclic antidepressant.
Those patients who are taking nitrates.
all of them
Beta - lactamase cleavage of Beta - lactam ring

42. Mannitol - contraindications?
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.
Local anesthetic.
- Constant AMOUNT eliminated per unit time. - Etoh & ASA
anuria - CHF

43. Antiarrhythmic class IV- effects?
Polymyxins
Pituitary hormone.
decrease conduction velocity - increase ERP - increase PR interval
Vd= (Amt. of drug in body/ Plasma drug conc.)

44. Antimicrobial prophylaxis for Meningococcal infection
post MI and digitalis induced arrhythmias
1. Gastric ulceration 2. Bleeding 3. Hyperventilation 4. Reye's syndrome 5. Tinnitus (CN VIII)
Rifampin (DOC) - minocycline
- Class III antiarrhythmics (sotalol) - class IA (quinidine)

45. What is the receptor affinity and clinical use of isoproterenol?
Foscarnet = pyroFosphate analog
It affects beta receptors equally and is used in AV heart block (rare).
- Cloazapine - carbamazapine - colchicine - PTU
for RSV

46. Acetazolamide - site of action?
Useful in muscle paralysis during surgery or mechanical ventilation.
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions
proximal convoluted tubule

47. List the mechanism - clinical use - & toxicity of Cisplatin.
Inhibits DNA dependent RNA polymerase
- Alkalating agent - testicular - bladder - ovary -& lung - Nephrotoxicity & CN VIII damage.
Inhalational general anesthetic.
effective in torsade de pointes and digoxin toxicity

48. What is the MOA for Acyclovir?
For serious - Gram + multidrug - resistant organisms
Inhibit viral DNA polymerase
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis
Interferes with microtubule function - disrupts mitosis - inhibits growth

49. What is a prerequisite for Acyclovir activation?
blocks SR Ca2+ channels
- Airway - Breathing - Circulation - Dextrose (thiamine & narcan) - ABCD
Antibiotic - protein synthesis inhibitor.
It must be Phosphorylated by Viral Thymidine Kinase

50. ___________ are Teratogenic
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
Aminoglycosides
DOC in diagnosing and abolishing AV nodal arrhythmias
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol