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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. Acetazolamide - mechanism?
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.
- Ammonium Chloride
Inhibits reabsorption of uric acid.
Slow - limited by half lives of clotting factors

2. What is clinical use for Carbenicillin - Piperacillin - and Ticarcillin?
Prevents the release of Ca from SR of skeletal muscle
GI distress - Skin rash - and Seizures at high plasma levels
Pseudomonas species and Gram - rods
Digoxin=urinary Digitoxin=biliary

3. What drug is used during the pregnancy of an HIV+ mother? - Why?
loop diuretics - thiazides
AZT - to reduce risk of Fetal Transmission
- Halothane - Valproic acid - acetaminophen - Amantia phalloides
Inhibits cGMP phosphodiesterase - casuing increased cGMP - smooth muscle relaxation in the corpus cavernosum - increased blood flow - and penile erection.

4. What is the mechanism of Leuprolide?
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
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
BM suppression (neutropenia - anemia) - Peripheral neuropathy
Erythromycin - Azithromycin - Clarithromycin

5. How is Amantadine used clinically?

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6. How does dantrolene work?
- Tetracycline - amiodarone - sulfonamides
Prevents the release of calcium from the sarcoplasmic reticulum of skeletal muscle.
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine
1. Acarbose 2. Miglitol

7. What are two Glitazones?
1. Pioglitazone 2. Rosiglitazone.
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)
- Vinca alkaloids(inhibit MT) - Paclitaxel
Lovastatin - Pravastatin - Simvastatin - Atorvastatin

8. What is the mechanism of action of the H2 Blockers?
Neurotoxicity - Acute renal tubular necrosis
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.
Reversible block of histamine H2 receptors
Inhibt Assembly of new virus by Blocking Protease Enzyme

9. What are two types of drugs that interfere with the action of Sucralfate and why?
- Ethanol - dialysis - & fomepizole
Sucralfate cannot work in the presence of antacids or H2 blockers because it requires an acidic environment to polymerize.
Ceftriaxone
Inhibition of 50S peptidyl transferase - Bacteriostatic

10. What are Aminoglycosides synergistic with?
ACE inhibitor.
fetal renal toxicity - hyperkalemia
Inhibit DNA Gyrase (topoisomerase II) - Bactericidal
Beta - lactam antibiotics

11. Name three calcium channel blockers?
Tetracycline - Doxycycline - Demeclocycline - Minocycline
Inhibits DNA dependent RNA polymerase
Dry flushed skin - due to inhibition of sympathetic post - ganglionic blockade on muscarinic receptors of sweat glands. All others are opposite of What would be expected.
Nifedipine - Verapamil - Diltiazem

12. What conditions are treated with Metronidazole?
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome
Giardiasis - Amoebic dysentery (E. histolytica) - Bacterial vaginitis (Gardnerella vaginalis) - Trichomonas
- Airway - Breathing - Circulation - Dextrose (thiamine & narcan) - ABCD
1. Antipyretic 2. Analgesic 3. Anti - inflammatory

13. What is the mechanism of action of Misoprostol?
- Nitrate - hydroxocobalamin thiosulfate
Misoprostol is a PGE1 analog that increases the production and secretion of the gastic mucous barrier.
Slow - limited by half lives of clotting factors
torsade de pointes

14. What are two indirect acting adrenergic agonists?
amphetamine and ephedrine
Irreversibly inhibits H+/K+ ATPase in stomach parietal cells.
To inhibit renal Dihydropeptidase I and decrease Imipenem inactivation in the renal tubules
Amphotericin B - Nystatin - Fluconazole/azoles

15. List the mechanism - clinical use - & toxicity of 6 MP.
- inhibits HGPRT (pur. Syn.) - Luk - Lymph
NO
- Formaldehyde & formic acid - severe acidosis & retinal damage
1. Antipyretic 2. Analgesic 3. Anti - inflammatory 4. Antiplatelet drug.

16. What is the MOA of Ribavirin?
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis
- Class III antiarrhythmics (sotalol) - class IA (quinidine)
Binds to the Pyrophosphate Binding Site of the enzyme
Slow - limited by half lives of clotting factors

17. What is the MOA of the RT Inhibitors?
Activates antithrombin III
Inhibit RT of HIV and prevent the incorporation of viral genome into the host DNA
Prevents the release of calcium from the sarcoplasmic reticulum of skeletal muscle.
CL= (rate of elimination of drug/ Plasma drug conc.)

18. What is a common side effect of Colchicine used to treat acute gout - especially When given orally?
Nephrotoxicity
Small lipid - soluble molecule
GI side effects. (Indomethacin is less toxic - more commonly used.)
Tetracycline - Doxycycline - Demeclocycline - Minocycline

19. What physiological effects was the Anes using Atropine to tx
Paranteral (IV - SC)
- Alkalinize urine & dialysis
SLUD (salivation - Lacrimation - urination - Defecation)as well as airway secretion - GI motility - acid secretions
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.

20. What is the mechanism of action of Probenacid used to treat chronic gout?
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.
Inhibits reabsorption of uric acid.
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity
Decreases synthesis of Mycolic Acid

21. What two vasodilators require simultaneous treatment with beta blockers to prevent reflex tachycardia and diuretics to prevent salt retention?
Doxycycline - because it is fecally eliminated
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic
Babiturate.
Hydralazine and Minoxidil

22. Name three Antiarrhythmic drugs in class IV.
check PFTs - LFTs - and TFTs
Verapamil - Diltiazem - Bepridil
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.
Staphlococcus aureus and Clostridium difficile (pseudomembranous colitis)

23. Where does Griseofulvin deposit?
ACE inhibitor.
Keratin containing tissues - e.g. - nails
Diarrhea - Urination - Miosis - Bronchospasm - Bradycardia - Excitation of skeletal muscle and CNS - Lacrimation - Sweating - and Salivation = DUMBBELS; also abdominal cramping
Large anionic polymer - acidic

24. What musculo - skeletal side effects in Adults are associated with Floroquinolones?
Tendonitis and Tendon rupture
Acetylcholine esterase
Chronic anticoagulation.
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)

25. Furosemide - clinical use?
Tricyclic antidepressant.
post MI and digitalis induced arrhythmias
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia
Diuresis in pateints with sulfa allergy

26. What is the mechanism of action of Acetaminophen?
No - warfarin - unlike heparin - can cross the placenta.
- Tetracycline
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.
- Tetracycline - amiodarone - sulfonamides

27. Acetazolamide - clinical uses?
Lipoxygenase
glaucoma - urinary alkalinization - metabolic alkalosis - altitude sickness
hyperkalemia - endocrine effects (gynecomastia - anti - androgen)
Anaerobes

28. Resistance mechanisms for Chloramphenicol
Modification via Acetylation
Due to the presence of a bulkier R group
Protamine Sulfate is used for rapid reversal of heparinization (positively charged molecule that binds to negatively charged heparin).
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.

29. What is Metronidazole used for clinically?
G6PD deficient individuals
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium
Decreases synthesis of Mycolic Acid
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow

30. What are the products and their toxicities of the metabolism of Ethylene Glycol by / alcohol dehydrogenase?
Chronic anticoagulation.
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels
- Oxalic acid - Acidosis & nephrotoxicity
Malaria (P. falciparum)

31. What are two toxicities of the Sulfonylureas?
Dermatophytes (tinea - ringworm)
The only local anesthetic with vasoconstrictive properties.
glaucoma - urinary alkalinization - metabolic alkalosis - altitude sickness
1. Hypoglycemia (more common with 2nd - generation drugs: glyburide - glipizide) 2. Disulfiram - like effects (not seen with 2nd - generation drugs).

32. How can Vancomycin - induced 'Red Man Syndrome' be prevented?
Pretreat with antihistamines and a slow infusion rate
Zidovudine (AZT) - Didanosine (ddI) - Zalcitabine (ddC) - Stavudine (d4T) - Lamivudine (3TC)
Blocks Norepi - but not Dopamine
Paranteral (IV - SC)

33. What is the mechanism of action of the Sulfonylureas?
Inhibit RT of HIV and prevent the incorporation of viral genome into the host DNA
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.
Dermatophytes (tinea - ringworm)
As an anticholinesterase it increases endogenous ACh and thus increases strength.

34. What are the phases of succinylcholine neuromuscular blockade?
- Ethanol - dialysis - & fomepizole
Spironolactone - Triamterene - Amiloride (the K+ STAys)
Nephrotoxicity
Phase 1 = prolonged depolarization - no antidote - effect potentiated by anticholinesterase; Phase 2 = repolarized but blocked - an anticholinesterase is the antidote for this phase.

35. Aztreonam ________ to penicillinase
is resistant
- Steroids - Tamoxifen
Amphetamine and Ephedrine
sedation - depression - nasal stuffiness - diarrhea

36. For Heparin What is the Site of action
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
Nephrotoxicity (esp. with Cephalosporins) - Ototoxicity (esp. with Loop Diuretics)
Flecainide - Encainide - Propafenone
Blood

37. How does Ganciclovir's toxicity relate to that of Acyclovir?
With an amino acid change of D- ala D- ala to D- ala D- lac
Ganciclovir is more toxic to host enzymes
Choline acetyltransferase
GI distress - Tooth discoloration and Inhibition of bone growth in children - Fanconi's syndrome - Photosensitivity

38. How are the Latent Hypnozoite (Liver) forms of Malaria (P. vivax - P.ovale) treated?
Nephrotoxicity
local anesthetic. CNS stimulation or depression. CV depression.
GI upset - Superinfections - Skin rashes - Headache - Dizziness
Primaquine

39. K+ sparing diuretics - toxicity?
Hydralazine and Minoxidil
orthostatic and exercise hypotension - sexual dysfunction - diarrhea
hyperkalemia - endocrine effects (gynecomastia - anti - androgen)
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis

40. Digitalis - site of action?
Immediate anticoagulation for PE - stroke - angina - MI - DVT.
check PFTs - LFTs - and TFTs
Na/K ATPase
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)

41. What is the most common cause of Pt noncompliance with Macrolides?
AV nodal cells
GI discomfort
Binds ergosterol - Disrupts fungal membranes
Rapid (seconds)

42. Why are albuterol and terbutaline effective in tx of acute asthmatic attacks?
These B-2 agonists cause respiratory smooth muscle to relax.
Nephrotoxicity
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome
Modification via Acetylation

43. Adverse effects of Hydrochlorothiazide?
hypokalemia - slight hyperlipidemia - hyperuricemia - lassitude - hypercalcemia - hyperglycemia
Nephrotoxicity (esp. with Cephalosporins) - Ototoxicity (esp. with Loop Diuretics)
Minor hepatotoxicity - Drug interactions (activates P450)
Beta1 more than B2

44. What are common side effects of Amphotericin B?
AluMINIMUM amount of feces.
Cephalosporins
local anesthetic. CNS stimulation or depression. CV depression.
Fever/Chills - Hypotension - Nephrotoxicity - Arrhythmias

45. What is the category and mechanism of action of Zileuton in Asthma treatment?
- Glucocorticoid withdrawal
Antileukotriene; blocks synthesis by lipoxygenase.
- S- phase anti - metabolite folate analogue - Luk - Lymp - sarc - RA - & psoriasis / - Reversible myelosuppression
effective in torsade de pointes and digoxin toxicity

46. What are the nondepolarizing neuromuscular blocking drugs?
fetal renal damage - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
- Shifts the curve to the right - increases Km
HSV - VZV - EBV - Mucocutaneous and Genital Herpes Lesions - Prophylaxis in Immunocompromised pts
Tubocurarine - atracurium - mivacurium - pancuronium - vecuronium - rapacuronium

47. Aztreonam is not usually...
Amphotericin B - Nystatin - Fluconazole/azoles
toxic
Yes - it does not cross the placenta.
Same as penicillin. Extended spectrum antibiotics

48. Adverse effect of Nitroprusside?
- Methylene blue
cyanide toxicity (releases CN)
Antimetabolite derivative of 6- mercaptopurine that interferes with the metablolism and synthesis of nucleic acid.
-100% oxygen - hyperbaric

49. What is the MOA for the Azoles?
Inhibit Ergosterol synthesis
IV vitamin K and fresh frozen plasma
Blocks viral penetration/uncoating; may act to buffer the pH of the endosome
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention

50. Cautions When using Amiodarone?
first dose orthostatic hypotension - dizziness - headache
Same as penicillin. Extended spectrum antibiotics
check PFTs - LFTs - and TFTs
Cyclooxygenases (COX I - COX II).