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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 are three toxicities of Propylthiouracil?
Ld= (CpxVd)/F Cp=plasma conc. F= Bioaval.
1. Skin rash 2. Agranulocytosis (rare) 3. Aplastic anemia
- Oral Contraceptives
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine

2. What is the category - mechanism of action - and particular use of beclomethasone and prednisone in Asthma treatment?
Non - Nucleosides
- Triggers apoptosis - CLL - Hodgkin's in MOPP - Cushing - like syndrome
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.)
Impairs the synthesis of vitamin K- dependent clotting factors

3. What is Metronidazole combined with for 'triple therapy'? Against What organism?
Tricyclic antidepressant.
Bismuth and Amoxicillin or Tetracycline; against Helobacter pylori
GI disturbances.
Lipoxygenase

4. Describe Phase I metabolism in liver(3)?
Babiturate.
- reduction - oxy - & hydrolysis - H2O sol. Polar product - P450
Binds ergosterol - Disrupts fungal membranes
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.

5. Are not penicillinase resistant
Carbenicillin - Piperacillin - and Ticarcillin
narcolepsy - obesity - and attention deficit disorder (I wouldn't recommend this)
Prevents the release of ACh - Which results in muscle paralysis.
sedation - positive Coombs' test

6. MOA for Penicillin (3 answers)?
1. Phospholipase A2 is prevented from releasing arachidonic acid 2. Decreases protein synthesis thus lowering amount of Cyclooxygenase enzymes
Acute gout.
1)Binds penicillin - binding proteins 2) Blocks transpeptidase cross - linking of cell wall 3) Activates autolytic enzymes
Butyrophenone (neuroleptic).

7. Name the common Aminoglycosides (5)
Dopamine; causes its release from intact nerve terminals
Increase target cell response to insulin.
Gentamicin - Neomycin - Amikacin - Tobramycin - Streptomycin
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic

8. List the specific antidote for this toxin: Warfarin
Inhibits bacterial Dihydrofolate Reductase - Bacteriostatic
thiazides - amiloride
- Vitamin K & fresh frozen plasma
decrease

9. Which of the following would atropine administration cause? Hypothermia - bradycardia - excess salivation - dry flushed skin - or diarrhea
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.
Epinephrine to treat anaphylaxis. Also useful if you have open angle glaucoma - asthma - or hypotension.
Interferes with microtubule function - disrupts mitosis - inhibits growth
As an anticholinesterase it increases endogenous ACh and thus increases strength.

10. For Heparin What is the Treatment for overdose
Protamine sulfate
local anesthetic. CNS stimulation or depression. CV depression.
Large anionic polymer - acidic
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine

11. What are the clinical uses for 3rd Generation Cephalosporins?
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
No - warfarin - unlike heparin - can cross the placenta.
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)
Megaloblastic anemia - Leukopenia - Granulocytopenia

12. Are Ampicillin and Amoxicillin are not...
1. Acarbose 2. Miglitol
penicillinase resistant
GI disturbances.
Overdose produces hepatic necrosis; acetaminophen metablolite depletes glutathione and forms toxic tissue adducts in liver.

13. What are the clinical uses for 1st Generation Cephalosporins?
Blocks viral penetration/uncoating; may act to buffer the pH of the endosome
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased
Gram + cocci - Proteus mirabilis - E. coli - Klebsiella pneumoniae (PEcK)
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.

14. Beta Blockers - BP?
Benzathine penicillin G
1. Meningococcal carrier state 2. Chemoprophylaxis in contacts of children with H. influenzae type B
not a sulfonamide - but action is the same as furosemide
decrease

15. What is the mecanism of action of the COX-2 inhibitors (celecoxib - rofecoxib)?
proarrhythmic
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine
Selectively inhibit cyclooxygenase (COX) isoform 2 - Which is found in inflammatory cells nad mediates inflammation and pain; spares COX-1 Which helps maintain the gastric mucosa.
In 4 half - lifes= (94%) T1/2 = (0.7x Vd)/CL

16. Which drug(s) cause this reaction: Stevens - Johnson syn. (3)?
GI intolerance (nausea - diarrhea) - Hyperglycemia - Lipid abnormalities - Thrombocytopenia (Indinavir)
Diarrhea - Urination - Miosis - Bronchospasm - Bradycardia - Excitation of skeletal muscle and CNS - Lacrimation - Sweating - and Salivation = DUMBBELS; also abdominal cramping
No. Atropine is used to reduce urgency in mild cystitis. So it would aggravate the urinary retention.
- Ethosuxamide - sulfonamides - lamotrigine

17. Name four Antiarrhythmic drugs in class III.
Sotalol - Ibutilide - Bretylium - Amiodarone
first dose orthostatic hypotension - dizziness - headache
Inhibits cGMP phosphodiesterase - casuing increased cGMP - smooth muscle relaxation in the corpus cavernosum - increased blood flow - and penile erection.
Methylxanthine.

18. Which drug(s) cause this reaction: Diabetes insipidus?
- Alkalating agent - testicular - bladder - ovary -& lung - Nephrotoxicity & CN VIII damage.
Inhibits DNA dependent RNA polymerase
- Lithium
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors

19. What are three toxicities of Leuprolied?
Prophylaxis for Influenza A - Rubella; Parkinson's disease
- Upper respiratory tract infections - pneumonias - STDs: Gram+ cocci (streptococcal infect in pts allergic to penicillin) - Mycoplasma - Legionella - Chlamydia - Neisseria
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased
1. Antiandrogen 2. Nausea 3. Vomiting

20. What would be the effect on blood pressure with infusion of the alpha -2 agonist clonidine?
Epinephrine to treat anaphylaxis. Also useful if you have open angle glaucoma - asthma - or hypotension.
alpha -1 > alpha -2; used as a pupil dilator - vasoconstrictor - and for nasal decongestion
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.
Gram - rods: Klebsiella species - Pseudomonas species - Serratia species

21. Which drug(s) cause this reaction: Gynecomastia (6)?
Anaerobes
Suramin
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens
Activates antithrombin III

22. How is Acyclovir used clinically?
HSV - VZV - EBV - Mucocutaneous and Genital Herpes Lesions - Prophylaxis in Immunocompromised pts
Inhibits bacterial Dihydrofolate Reductase - Bacteriostatic
- Phase I (clinical tests) - Phase II - Phase III - PhaseIV (surveillance)
penicillinase resistant

23. What drug is given for Pneumocystis carinii prophylaxis?
Pentamidine
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids
- Nitrate - hydroxocobalamin thiosulfate
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.

24. Amprotericin B ___________ the BBB
- Ethosuxamide - sulfonamides - lamotrigine
Does not cross
Acute gout.
Rifampin - Ethambutol - Streptomycin - Pyrazinamide - Isoniazid (INH)

25. Acetazolamide - mechanism?
Digitoxin 70% Digoxin 20-40%
Phosphorylation by a Viral Kinase
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.
Diarrhea

26. Ryanodine - site of action?
blocks SR Ca2+ channels
anticholinesterase glaucoma
Pentavalent Antimony
hyperkalemia - endocrine effects (gynecomastia - anti - androgen)

27. What is the loading dose formula?
Ld= (CpxVd)/F Cp=plasma conc. F= Bioaval.
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic
Dopamine
Digitoxin 70% Digoxin 20-40%

28. What microorganisms are clinical indications for Tetracycline therapy?

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29. What organisms does Griseofulvin target?
Blocking muscarinic receptors in the circular fibers of the eye - results in unopposed action of radial muscles to dilate.
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.
Dermatophytes (tinea - ringworm)
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.

30. Aztreonam is not ________ with penicillins
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis
Beta lactams - inhibit cell wall synthesis - Bactericidal
Slow - limited by half lives of clotting factors
cross - allergenic

31. What are are the Sulfonylureas (general description) and What is their use?
HTN - CHF - calcium stone formation - nephrogenic DI.
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity

32. List the mechanism - clinical use - & toxicity of Etoposide.
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.
-100% oxygen - hyperbaric
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
Large anionic polymer - acidic

33. Clonidine is the preferred sym pathomimetic tx of HTN in pts with renal disease - why??
G6PD deficient individuals
Finasteride inhibits 5 Alpha - reductase - this decreases the conversion of testosterone to dihydrotestosterone - useful in BPH
Bethanechol - Neostigmine - physostigmine
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow

34. Resistance mechanisms for Tetracycline
Decreased uptake or Increased transport out of cell
- Normalize K+ - Lidocaine - & Anti - dig Mab
cyanide toxicity (releases CN)
Phase 1 = prolonged depolarization - no antidote - effect potentiated by anticholinesterase; Phase 2 = repolarized but blocked - an anticholinesterase is the antidote for this phase.

35. Which diuretics decrease urine Ca2+?
- Tricyclic antidepressants
thiazides - amiloride
Cell membrane Ca2+ channels of cardiac sarcomere
GI distress - Tooth discoloration and Inhibition of bone growth in children - Fanconi's syndrome - Photosensitivity

36. What populations are Floroquinolones contraindicated in? Why?
Pregnant women - Children; because animal studies show Damage to Cartilage
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
1. Antipyretic 2. Analgesic 3. Anti - inflammatory
Blood

37. Antimicrobial prophylaxis for Gonorrhea
Ceftriaxone
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)
- Tetracycline - amiodarone - sulfonamides
Rifampin (DOC) - minocycline

38. Which diuretics cause acidosis?
Pentavalent Antimony
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.
Giardiasis - Amoebic dysentery (E. histolytica) - Bacterial vaginitis (Gardnerella vaginalis) - Trichomonas
carbonic anhydrase inhibitors - K+ sparing diuretics

39. Why does atropine dilate the pupil?
Ca2+ (Loops Lose calcium)
- partial agonist can have increased - decreased - /A21or equal potency as full agonist. - Potency is an independent factor.
Blocking muscarinic receptors in the circular fibers of the eye - results in unopposed action of radial muscles to dilate.
VACUUM your Bed Room'

40. Hydrochlorothiazide - mechanism?
Antimetabolite derivative of 6- mercaptopurine that interferes with the metablolism and synthesis of nucleic acid.
Topical and Oral - for Oral Candidiasis (Thrush)
- Alkalinize urine & dialysis
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.

41. Name several common Macrolides (3)
Erythromycin - Azithromycin - Clarithromycin
Ciprofloxacin - Norfloxacin - Ofloxacin - Grepafloxacin - Enoxacin - Nalidixic acid
- Shifts the curve to the right - increases Km
Benzathine penicillin G

42. What enzyme does Zileuton inhibit?
Liver
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.
No
Lipoxygenase

43. What enzyme is responsible for the production of Ach from Acetyl CoA and Choline
severe hypertension - CHF
Zidovudine (AZT) - Didanosine (ddI) - Zalcitabine (ddC) - Stavudine (d4T) - Lamivudine (3TC)
Epinephrine
Choline acetyltransferase

44. Mg+- clinical use?
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.)
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility
effective in torsade de pointes and digoxin toxicity
Inhibits cGMP phosphodiesterase - casuing increased cGMP - smooth muscle relaxation in the corpus cavernosum - increased blood flow - and penile erection.

45. Which antimuscarinic agents are used in producing mydriasis and cycloplegia?
Well tolerated in general but occasionally - Nephrotoxicity - Ototoxicity - Thrombophlebitis - diffuse flushing='Red Man Syndrome'
viral kinase
atropine - homatropine - tropicamide
Triple Therapy' 2 Nucleoside RT Inhibitors with a Protease Inhibitor

46. Esmolol - short or long acting?
Binds to the Pyrophosphate Binding Site of the enzyme
Binds Ergosterol - forms Membrane Pores that Disrupt Homeostatis
very short acting
Neutropenia

47. Which drug(s) cause this reaction: Tendonitis and rupture?
Inhibits cell wall synthesis ( binds to PBP3). A monobactam
Post - op and neurogenic ileus and urinary retention - myasthenia gravis - and reversal of neuromuscular junction blockade (post - op) through anticholinesterase activity.
Inhibit Ergosterol synthesis
- Fluoroquinolones

48. Which drug(s) cause this reaction: Drug induced Parkinson's (4) ?
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).
Methylxanthine.
- Haloperidol - chlorpromazine - reserpine - MPTP
Interferes with microtubule function - disrupts mitosis - inhibits growth

49. Which antimicrobial classes inhibit protein synthesis at the 30S subunit? (2)
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic
Used in combination therapy with SMZ to sequentially block folate synthesis
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium

50. Ethacrynic Acid - toxicity?
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone
Antifungal.
NO HYPERURICEMIA - NO SULFA AllERGY; same as furosemide otherwise
GI side effects. (Indomethacin is less toxic - more commonly used.)