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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. List the mechanism - clinical use - & toxicity of Paclitaxel.
Post - op and neurogenic ileus and urinary retention - myasthenia gravis - and reversal of neuromuscular junction blockade (post - op) through anticholinesterase activity.
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.
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
- Hydralazine - Procainamide - INH - phenytoin

2. What is the formula for Clearance (CL)
CL= (rate of elimination of drug/ Plasma drug conc.)
effective in torsade de pointes and digoxin toxicity
Epinephrine
atropine - homatropine - tropicamide

3. Which drug(s) cause this reaction: Tubulointerstitial Nephritis (5)?
- Methotrexate - 5 FU - 6 mercaptopurine
Gram - rods: Klebsiella species - Pseudomonas species - Serratia species
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)

4. What are common toxicities associated with Tetracyclines?

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5. Nifedipine has similar action to?
Botulinum
Useful in muscle paralysis during surgery or mechanical ventilation.
- Tamoxifen
Nitrates

6. Which drug(s) cause this reaction: Atropine - like side effects?
- Tricyclic antidepressants
Systemic mycoses
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.

7. What is the clinical use of Mifepristone (RU486)?
Penicillin.
DHPG (dihydroxy-2- propoxymethyl guanine)
Abortifacient.
Due to the presence of a bulkier R group

8. Aztreonam ________ to penicillinase
Used in combination therapy with SMZ to sequentially block folate synthesis
Bethanechol - Neostigmine - physostigmine
thiazides - amiloride
is resistant

9. Which receptors does phenylephrine act upon?
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
Choline acetyltransferase
alpha -1 > alpha -2; used as a pupil dilator - vasoconstrictor - and for nasal decongestion
It inhibits release of NE.

10. Which drug(s) cause this reaction: Torsade de pointes (2)?
- Class III antiarrhythmics (sotalol) - class IA (quinidine)
- Chlorpromazine - thioridazine - haloperidol
It acts presynaptically to increase NE release.
Constant FRACTION eliminated per unit time.(exponential)

11. Resistance mechanisms for Tetracycline
Decreased uptake or Increased transport out of cell
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia
Botulinum
Nonspecific beta - agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Adverse effect is tachycardia (Beta 1).

12. What is the difference in receptor affinity of epinephrine at low doses? High doses?

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13. Which cancer drugs work at the level of mRNA(2)?
Prophylaxis for Influenza A - Rubella; Parkinson's disease
- Steroids - Tamoxifen
VACUUM your Bed Room'
all of them

14. What are four thrombolytics?
Activates antithrombin III
1. Streptokinase 2. Urokinase 3. tPA (alteplase) - APSAC (anistreplase)
Inhibition of 50S peptidyl transferase - Bacteriostatic
Oral

15. What are two conditions in Which COX-2 inhibitors might be used?
Misoprostol is contraindicated in women of childbearing potential because it is an abortifacient.
local anesthetic. CNS stimulation or depression. CV depression.
Rheumatoid and osteoarthritis.
- Cimetidine - ketoconazole - grapefruit juice - erythromycin - INH - sulfonamides

16. What are the clinical uses for 3rd Generation Cephalosporins?
Ganciclovir is more toxic to host enzymes
Inhibition of 50S peptidyl transferase - Bacteriostatic
- Methylene blue
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)

17. IV Penicillin
sedation - positive Coombs' test
Penicillin - G
Methylation of rRNA near Erythromycin's ribosome binding site
GI upset - Superinfections - Skin rashes - Headache - Dizziness

18. How do Sulfonamides act on bacteria?
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
- Tetracycline - amiodarone - sulfonamides
- N- acetylcystine
sedation - positive Coombs' test

19. MOA: Block peptidoglycan synthesis
Bacitracin - Vancomycin
Early myocardial infarction.
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.
1. Skin rash 2. Agranulocytosis (rare) 3. Aplastic anemia

20. For Warfarin What is the Duration of action
INH: Injures Neurons and Hepatocytes
The PT.
Chronic (weeks or months)
- Vitamin K & fresh frozen plasma

21. A 12yo patient was treated for a reaction to a bee sting - What drug provides the best coverage of sympathomimetic receptors?
Indirect agonist - uptake inhibitor
- Oral Contraceptives
Epinephirine(Alpha1 -2 and Beta 1 -2)
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents

22. Name the common Azoles
Ataxia - Dizziness - Slurred speech
Fluconazole - Ketoconazole - Clotrimazole - Miconazole - Itraconazole
compensatory tachycardia - fluid retention - lupus - like syndrome
Increase target cell response to insulin.

23. What effect would atropine have on a patient with peptic ulcer disease?
Forms toxic metabolites in the bacterial cell - Bactericidal
Lovastatin - Pravastatin - Simvastatin - Atorvastatin
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).

24. What is the clinical utility of cocaine?
TMP- SMZ (DOC) - aerosolized pentamidine
Prevents the release of Ca from SR of skeletal muscle
The only local anesthetic with vasoconstrictive properties.
1. Antipyretic 2. Analgesic 3. Anti - inflammatory 4. Antiplatelet drug.

25. Would blockade of muscarininc receptors in the bladder be useful in treating urinary retention?
No. Atropine is used to reduce urgency in mild cystitis. So it would aggravate the urinary retention.
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis
Carbenicillin - Piperacillin - and Ticarcillin
Blocks Peptide Bond formation at the 50S subunit - Bacteriostatic

26. What is the category - method of use - and adverse effects of Salmeterol in Asthma treatment?
Acetaminophen has antipyretic and analgesic properties - but lacks anti - inflammatory properties.
As an anticholinesterase it increases endogenous ACh and thus increases strength.
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.
Post - op and neurogenic ileus and urinary retention - myasthenia gravis - and reversal of neuromuscular junction blockade (post - op) through anticholinesterase activity.

27. What is the effect of guanethidine on adrenergic NE release?
Digitoxin 168hrs Digoxin 40 hrs
Clavulanic acid
It inhibits release of NE.
Give an antichloinesterase - neostigmine - edrophonium - etc

28. List the specific antidote for this toxin: Carbon monoxide
-100% oxygen - hyperbaric
No. Atropine is used to reduce urgency in mild cystitis. So it would aggravate the urinary retention.
Chronic Hepatitis A and B - Kaposi's Sarcoma
Interferes with microtubule function - disrupts mitosis - inhibits growth

29. List the specific antidote for this toxin: Salicylates
Oral treatment of superficial infections
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased
compensatory tachycardia - fluid retention - lupus - like syndrome
- Alkalinize urine & dialysis

30. Digoxin v. Digitoxin: half life?
Paranteral (IV - SC)
Digitoxin 168hrs Digoxin 40 hrs
- Act on same receptor - Full has greater efficacy
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.

31. What organisms does Griseofulvin target?
Dermatophytes (tinea - ringworm)
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens
toxic
Polymyxin B - Polymyxin E

32. Are penicillinase resistant
1. Antiandrogen 2. Nausea 3. Vomiting
Hypokalemic metabolic alkalosis - hyponatremia - hyperGlycemia - hyperLipidemia - hyperUricemia - hyperCalcemia - sulfa allergy.
Methicillin - Nafcillin - and Dicloxacillin
torsade de pointes - excessive Beta block

33. What is the memory key for Metronidazole's clinical uses?
GET on the Metro
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention
1. Weight gain 2. Hepatotoxicity (troglitazone)
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.

34. What is the mechanism of Azathioprine?
Beta lactams - inhibit cell wall synthesis - Bactericidal
Gram + - Gram - - Norcardia - Chlamydia
Antimetabolite derivative of 6- mercaptopurine that interferes with the metablolism and synthesis of nucleic acid.
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.

35. What are the major toxic side effects of Imipenem/cilastatin?
GI distress - Skin rash - and Seizures at high plasma levels
Muscarinic antagonist; competatively blocks muscarinic receptors - preventing bronchoconstriction.
Only in limited amounts
Saquinavir - Ritonavir - Indinavir - Nelfinavir

36. What is the clinical use for Nystatin?
Topical and Oral - for Oral Candidiasis (Thrush)
CL= (rate of elimination of drug/ Plasma drug conc.)
GI upset
Giardiasis - Amoebic dysentery (E. histolytica) - Bacterial vaginitis (Gardnerella vaginalis) - Trichomonas

37. What are common serious side effects of Aminoglycosides and What are these associated with?
Bethanechol - Neostigmine - physostigmine
impotence - exacerbation of asthma - CV effects - CNS effects - may mask hypoclycemia
very short acting
Nephrotoxicity (esp. with Cephalosporins) - Ototoxicity (esp. with Loop Diuretics)

38. List the specific antidote for this toxin: Tricyclic antidepressants
- NaHCO3
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.

39. What is Fluconazole specifically used for?
Does not cross
Cryptococcal meningitis in AIDS patients and Candidal infections of all types
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels
Inhibit RT of HIV and prevent the incorporation of viral genome into the host DNA

40. What are common toxic side effects of Sulfonamides? (5)
- Hypersensitivity reactions - Hemolysis - Nephrotoxicity (tubulointerstitial nephritis) - Kernicterus in infants Displace other drugs from albumin (e.g. - warfarin)
Chronic gout.
Clavulanic acid
Abortifacient.

41. What is the clinical use for Warfarin?
Hexamethonium is a nicotinic antagonist - and thus is a ganglionic blocker.
Chronic anticoagulation.
Local anesthetic.
- Class III antiarrhythmics (sotalol) - class IA (quinidine)

42. Which drug(s) cause this reaction: Extrapyramidal side effects (3)?
- Chlorpromazine - thioridazine - haloperidol
Hormone synthesis inhibition (Gynecomastia) - Liver dysfunction (Inhibits CYP450) - Fever - Chills
Same as penicillin. Extended spectrum antibiotics
Gram + cocci - Gram - rods - and Anerobes

43. What is the MOA of Isoniazid (INH)?
Cardiac glycoside (inotropic agent).
dizziness - flushing - constipation (verapamil) - nausea
Penicillin.
Decreases synthesis of Mycolic Acid

44. Foscarnet toxicity?
Ceftriaxone
Inhibt Assembly of new virus by Blocking Protease Enzyme
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.
Nephrotoxicity

45. What type of gout is treated with Colchicine?
IV vitamin K and fresh frozen plasma
Acute gout.
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.
Ganciclovir is more toxic to host enzymes

46. What are the clinical indications for Azole therapy?
Norepinephrine
check PFTs - LFTs - and TFTs
Systemic mycoses
cholestyramine - colestipol

47. How is Ganciclovir used clinically?
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.
- Antipsychotics
Nevirapine - Delavirdine
CMV - esp in Immunocompromised patients

48. What is treated with Chloroquine - Quinine - Mefloquine?
Malaria (P. falciparum)
Nonspecific beta - agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Adverse effect is tachycardia (Beta 1).
Minor hepatotoxicity - Drug interactions (activates P450)
1. Taken daily 2. No protection against STDs 3. Raises triglycerides 4. Depression - weight gain - nausea - HTN 5. Hypercoagulable state

49. What is the category of drug names ending in - ane (e.g. Halothane)
Minor hepatotoxicity - Drug interactions (activates P450)
torsade de pointes
Rifampin - Ethambutol - Streptomycin - Pyrazinamide - Isoniazid (INH)
Inhalational general anesthetic.

50. Mannitol - mechanism?
Paranteral (IV - SC)
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow
Protamine Sulfate is used for rapid reversal of heparinization (positively charged molecule that binds to negatively charged heparin).
Meningitis (H. influenza - N. meningitidis - S. pneumoniae) - Conserative treatment due to toxicities