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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. How do Sulfonamides act on bacteria?
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
AZT - to reduce risk of Fetal Transmission
Atropine pts are suffering from Cholinestrase inhibitor poisining (Nerve gas/Organophosphate poisining)

2. What organisms does Griseofulvin target?
Bleeding.
PT
1. Renal damage 2. Aplastic anemia 3. GI distress
Dermatophytes (tinea - ringworm)

3. MOA: Disrupt bacterial/fungal cell membranes
Polymyxins
hypertension - angina - arrhythmias
Beta 2 agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Use during acute exacerbation.
Digitoxin>95% Digoxin 75%

4. List the specific antidote for this toxin: Methanol & Ethylene glycol
It affects beta receptors equally and is used in AV heart block (rare).
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
Inhibits formation of Initiation Complex - causes misreading of mRNA - Bactericidal
- Ethanol - dialysis - & fomepizole

5. Mg+- clinical use?
- Glucagon
effective in torsade de pointes and digoxin toxicity
HSV - VZV - EBV - Mucocutaneous and Genital Herpes Lesions - Prophylaxis in Immunocompromised pts
Can affect absorption - bioavailability - or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying.

6. In coma situations you rule out What (7)?

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7. What is the MOA for Clindamycin?
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.
Blocks Peptide Bond formation at the 50S subunit - Bacteriostatic
Benzodiazepine.
Giardiasis - Amoebic dysentery (E. histolytica) - Bacterial vaginitis (Gardnerella vaginalis) - Trichomonas

8. How is Acyclovir used clinically?
HSV - VZV - EBV - Mucocutaneous and Genital Herpes Lesions - Prophylaxis in Immunocompromised pts
AmOxicillin has greater Oral bioavailability
1. Renal damage 2. Aplastic anemia 3. GI distress
- Oxalic acid - Acidosis & nephrotoxicity

9. For Heparin What is the Mechanism of action
Increase target cell response to insulin.
Extended spectrum penicillin: certain Gram + bacteria and Gram - rods
Activates antithrombin III
Lovastatin - Pravastatin - Simvastatin - Atorvastatin

10. For Warfarin What is the Route of administration
Beta antagonist.
cortical collecting tubule
Oral
- Flumazenil

11. Verapamil has similar action to?
Beta Blockers
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
Acute gout.
AZT

12. What parasitic condition is treated with Ivermectin?

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13. Which cancer drugs work at the level of proteins(2)?
Acetylcholine esterase
Gram - rods: Klebsiella species - Pseudomonas species - Serratia species
- Vinca alkaloids(inhibit MT) - Paclitaxel
Antibiotic - protein synthesis inhibitor.

14. Antimicrobial prophylaxis for Meningococcal infection
Fast vs. Slow Acetylators
Norepinephrine
Rifampin (DOC) - minocycline
1.Gram - rods of the Urinary and GI tracts (including Pseudomonas) 2.Neisseria 3. Some Gram + organisms

15. What are three toxicities of Leuprolied?
Interferes with microtubule function - disrupts mitosis - inhibits growth
1. Antiandrogen 2. Nausea 3. Vomiting
Acetylcholinesterase; ACh is broken down into choline and acetate.
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine

16. MOA: Block protein synthesis at 50s subunit
Foscarnet = pyroFosphate analog
reversible SLE- like syndrome
prevention of nodal arrhythmias (SVT)
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)

17. Toxic effects of TMP include?
Digitoxin 70% Digoxin 20-40%
- DNA intercalator - testicular & lymphomas - Pulmonary fibrosis mild myelosuppression.
Megaloblastic anemia - Leukopenia - Granulocytopenia
aPTT (intrinsic pathway)

18. How is Ganciclovir used clinically?
Ibuprofen - Naproxen - and Indomethacin
Immediate anticoagulation for PE - stroke - angina - MI - DVT.
CMV - esp in Immunocompromised patients
Directly of indirectly aid conversion of plasminogen to plasmin Which cleaves thrombin and fibrin clots. (It is claimed that tPA specifically converts fibrin - bound plasminogen to plasmin.)

19. List the specific antidote for this toxin: Heparin
Blastomyces - Coccidioides - Histoplasma - C. albicans; Hypercortisolism
- Protamine
- Flumazenil
- Ethosuxamide - sulfonamides - lamotrigine

20. What enzyme is responsible for the production of Ach from Acetyl CoA and Choline
- Normalize K+ - Lidocaine - & Anti - dig Mab
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.
Choline acetyltransferase
- Tetracycline

21. Explain differences between full and partial agonists(2).
- Act on same receptor - Full has greater efficacy
In treatment of malignant hyperthermia - due to concomitant use of halothane and succinylcholine. Also in neuroleptic malignant syndrome - a toxicity of antipsychotic drugs.
for RSV
all of them

22. Name some common Sulfonamides (4)
Inhibits cell wall synthesis ( binds to PBP3). A monobactam
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine
Nucleosides
Only in limited amounts

23. Name some common Tetracyclines (4)
Acts as a wide spectrum carbapenem
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens
Tetracycline - Doxycycline - Demeclocycline - Minocycline
- Penicillin

24. What is a mnemonic to remember Amantadine's function?
Beta Blockers
Blocks Influenza A and RubellA; causes problems with the cerebellA
1. Pioglitazone 2. Rosiglitazone.
- Methotrexate - 5 FU - 6 mercaptopurine

25. As an Anes you want to use a depolarizing neuromuscular blocking drug on your pt - What do you use
Succinylcholine
Epinephirine(Alpha1 -2 and Beta 1 -2)
Fluconazole - Ketoconazole - Clotrimazole - Miconazole - Itraconazole
Cephalosporin: 1) has a 6 member ring attached to the Beta lactam instead of a 5 member ring 2)has an extra functional group ( attached to the 6 member ring)

26. What is the effect of guanethidine on adrenergic NE release?
It inhibits release of NE.
- Dimercaprol - succimer
Bacitracin - Vancomycin
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more

27. What enzyme does Zileuton inhibit?
Pituitary hormone.
Prefers beta's at low doses - but at higher doses alpha agonist effects are predominantly seen.
Lipoxygenase
1. Better bioavailability 2. 2 to 4 times longer half life 3. Can be administered subcutaneously 4. Does not require laboratory monitoring

28. What are common serious side effects of Aminoglycosides and What are these associated with?
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.
Nephrotoxicity (esp. with Cephalosporins) - Ototoxicity (esp. with Loop Diuretics)
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.
not a sulfonamide - but action is the same as furosemide

29. What are Amantadine - associated side effects?
Nifedipine - Verapamil - Diltiazem
Malaria (P. falciparum)
Ataxia - Dizziness - Slurred speech
Inhibits formation of Initiation Complex - causes misreading of mRNA - Bactericidal

30. How is Trimethoprim used clinically?
Mycobacterium tuberculosis - the only agent used as solo prophylaxis against TB
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain
Used in combination therapy with SMZ to sequentially block folate synthesis
Rheumatoid and osteoarthritis.

31. What is the category of drug names ending in - operidol (e.g. Haloperidol)
all of them
- Constant AMOUNT eliminated per unit time. - Etoh & ASA
Butyrophenone (neuroleptic).
- Aminocaproic acid

32. How are Interferons (INF) used clinically?

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33. What is the category of drug names ending in - olol (e.g. Propranolol)
Hexamethonium is a nicotinic antagonist - and thus is a ganglionic blocker.
Beta antagonist.
Keratin containing tissues - e.g. - nails
vasodilator - increases cGMP to induce smooth muscle relaxation (arterioles>veins; afterload reduction)

34. How is Ganciclovir activated?
Rare.
Acute gout.
Phosphorylation by a Viral Kinase
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.

35. Which drug(s) cause this reaction: Adrenocortical Insufficiency
K+ wasting - metabolic alkalosis - hypotension - ototoxicity
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
GI distress - Tooth discoloration and Inhibition of bone growth in children - Fanconi's syndrome - Photosensitivity
- Glucocorticoid withdrawal

36. What is the mechanism of action of Mifepristone (RU486)?
Competitive inibitor of progestins at progesterone receptors.
Give an antichloinesterase - neostigmine - edrophonium - etc
dizziness - flushing - constipation (verapamil) - nausea
- Metronidazole - certain cephalosporins - procarbazine - sulfonylureas

37. What are Methicillin - Nafcillin - and Dicloxacillin used for clinically?
Staphlococcus aureus
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.
Alpha -1 antagonist
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity

38. Ethacrynic Acid - mechanism?
not a sulfonamide - but action is the same as furosemide
When pts have Low CD4+ (< 500 cells/cubic mm) or a High Viral Load
Rheumatoid and osteoarthritis.
physostigmine

39. What are three possible complications of Heparin therapy?
- Alkalating agent - testicular - bladder - ovary -& lung - Nephrotoxicity & CN VIII damage.
In 4 half - lifes= (94%) T1/2 = (0.7x Vd)/CL
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions
bradycardia - AV block - CHF

40. Quinidine - toxicity?
- A57Blue lines in gingiva & long bones - Encephalopathy & Foot drop - Abdominal colic / - Sideroblastic anemia
Overdose produces hepatic necrosis; acetaminophen metablolite depletes glutathione and forms toxic tissue adducts in liver.
- Acetaldehyde - Nausea - vomiting - headache - & hypotension
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval

41. What is the mechanism of action of Ticlopidine - Clopidogrel
Misoprostol is contraindicated in women of childbearing potential because it is an abortifacient.
They inhibit reuptake of NE at the nerve terminal (as does cocaine).
very short acting
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.

42. Steady state concentration is reached in __ number of half - lifes
Enterobacter
In 4 half - lifes= (94%) T1/2 = (0.7x Vd)/CL
sedation - positive Coombs' test
decrease conduction velocity - increase ERP - increase PR interval

43. When is Rifampin not used in combination with other drugs?
Benzodiazepine.
Sucralfate cannot work in the presence of antacids or H2 blockers because it requires an acidic environment to polymerize.
- Act on same receptor - Full has greater efficacy
1. Meningococcal carrier state 2. Chemoprophylaxis in contacts of children with H. influenzae type B

44. Which drug(s) cause this reaction: Hepatitis?
- Chloramphenicol - benzene - NSAIDS - PTU - phenytoin
Cephalosporin: 1) has a 6 member ring attached to the Beta lactam instead of a 5 member ring 2)has an extra functional group ( attached to the 6 member ring)
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome
- Isoniazid

45. Ryanodine - site of action?
blocks SR Ca2+ channels
ARF - shock - drug overdose - decrease intracranial/intraocular pressure
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.
Misoprostol is contraindicated in women of childbearing potential because it is an abortifacient.

46. What microorganisms is Aztreonam not effective against?
The only local anesthetic with vasoconstrictive properties.
Phase 1 = prolonged depolarization - no antidote - effect potentiated by anticholinesterase; Phase 2 = repolarized but blocked - an anticholinesterase is the antidote for this phase.
Gram + and Anerobes
- Vinca alkaloids(inhibit MT) - Paclitaxel

47. Acetaldehyde is metabolized by Acetaldehyde dehydrogenase - Which drug inhibs this enzyme?
CMV Retinitis in IC pts When Ganciclovir fails
Inhibits cGMP phosphodiesterase - casuing increased cGMP - smooth muscle relaxation in the corpus cavernosum - increased blood flow - and penile erection.
- NaHCO3
- Disulfram & also sulfonylureas - metronidazole

48. What is the receptor affinity and clinical use of isoproterenol?
Ca2+ (Loops Lose calcium)
Dopamine
Bacitracin - Vancomycin
It affects beta receptors equally and is used in AV heart block (rare).

49. Which drug(s) cause this reaction: Stevens - Johnson syn. (3)?
thiazides - amiloride
anuria - CHF
- Ethosuxamide - sulfonamides - lamotrigine
Hypersensitivity reactions

50. What are toxic side effects for Metronidazole?
Gram + cocci - Gram - rods - and Anerobes
Binds ergosterol - Disrupts fungal membranes
Disulfiram - like reaction with EtOH - Headache
Headache - flushing - dyspepsia - blue - green color vision.