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USMLE Step 1 Pharmacology

Subjects : health-sciences, usmle-step-1

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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. Beta Blockers - BP?
loop diuretics - spironolactone
Decreases synthesis of Mycolic Acid
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased
decrease

2. What are two mechanisms of action of Propythiouracil?
Digitoxin>95% Digoxin 75%
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.
Systemic mycoses
-100% oxygen - hyperbaric

3. Why is reserpine effective in treating HTN?
PT
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity
Blocks viral penetration/uncoating; may act to buffer the pH of the endosome
Reserpine inhibits dopamine transport into vesicles - attenuating its conversion to NE by dopamine beta - hydroxylase.

4. Why is pyridostigmine effective in the treatment of myasthenia gravis?
Potent immunosuppressive used in organ transplant recipients.
all except the K+ sparing diuretics Spironolactone - Triamterene - Amiloride
As an anticholinesterase it increases endogenous ACh and thus increases strength.
Amphotericin B - Nystatin - Fluconazole/azoles

5. Ca2+ channel blockers - mechanism?
Aminoglycosides
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility
- Tricyclic antidepressants
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.

6. What is the MOA of Ganciclovir?
Inhibits CMV DNA polymerase
With supplemental Folic Acid
SLUD (salivation - Lacrimation - urination - Defecation)as well as airway secretion - GI motility - acid secretions
1. Pioglitazone 2. Rosiglitazone.

7. What is used to reverse the action of Heparin?
Protamine Sulfate is used for rapid reversal of heparinization (positively charged molecule that binds to negatively charged heparin).
- Quinidine - quinine
Beta 2 agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Use during acute exacerbation.
Keratin containing tissues - e.g. - nails

8. Why is carbachol and pilocarpine useful in treatment of glaucoma?
physostigmine
hyperaldosteronism - K+ depletion - CHF
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).
propanolol - esmolol - metoprolol - atenolol - timolol

9. What are the four conditions in Which Omeprazole - Lansoprazole is used?
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome
IV vitamin K and fresh frozen plasma
- Atropine & pralidoxime
- Phase I (clinical tests) - Phase II - Phase III - PhaseIV (surveillance)

10. What is the mechanism of action of Allopurinol used to treat chronic gout?
DHPG (dihydroxy-2- propoxymethyl guanine)
Inhibits DNA dependent RNA polymerase
1) Hypersensitivity reactions 2) Increased nephrotoxicity of Aminoglycosides 3) Disulfiram - like reaction with ethanol (those with a methylthiotetrazole group - e.g. - cefamandole)
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.

11. Antiarrhythmic class II- toxicity?
- Upper respiratory tract infections - pneumonias - STDs: Gram+ cocci (streptococcal infect in pts allergic to penicillin) - Mycoplasma - Legionella - Chlamydia - Neisseria
Ld= (CpxVd)/F Cp=plasma conc. F= Bioaval.
impotence - exacerbation of asthma - CV effects - CNS effects - may mask hypoclycemia
vascular sm. Mus.: Nifedipine>Diltiazem>Verapamil

12. Which diuretics decrease urine Ca2+?
NO
1. Antipyretic 2. Analgesic 3. Anti - inflammatory
thiazides - amiloride
Blastomyces - Coccidioides - Histoplasma - C. albicans; Hypercortisolism

13. What are three unwanted effects of Mifepristone?
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain
Pentamidine
Beta -2 agonist.
Pseudomonas species and Gram - rods

14. Resistance mechanisms for Aminoglycosides
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
Modification via Acetylation - Adenylation - or Phosphorylation
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.
Beta Blockers

15. What is action of insulin in the liver - in muscle - and in adipose tissue?
It acts presynaptically to increase NE release.
Increase target cell response to insulin.
Antifungal.
1. In liver - increases storage of glucose as glycogen. 2. In muscle - stimulates glycogen and protein synthesis - and K+ uptake. 3. In adipose tissue - facilitates triglyceride storage.

16. What is the effect of guanethidine on adrenergic NE release?
Lovastatin - Pravastatin - Simvastatin - Atorvastatin
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.
It inhibits release of NE.
proximal convoluted tubule - thin descending limb - and collecting duct

17. What microorganisms are Aminoglycosides ineffective against?
Anaerobes
- Flumazenil
Nephrotoxicity
Acetylcholinesterase; ACh is broken down into choline and acetate.

18. What organism is Imipenem/cilastatin the Drug of Choice for?
Inhibit steroid synthesis - used in the treatment of polycystic ovarian syndrome to prevent hirsutism.
Enterobacter
- Phase I (clinical tests) - Phase II - Phase III - PhaseIV (surveillance)
Nevirapine - Delavirdine

19. Antiarrhythmic class IC- effects?
Phase 1 = prolonged depolarization - no antidote - effect potentiated by anticholinesterase; Phase 2 = repolarized but blocked - an anticholinesterase is the antidote for this phase.
Paranteral (IV - SC)
NO AP duration effect. useful in V- tach that progresses to V- fib and in intractable SVT Last RESORT
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.

20. What are the side effects of Rifampin?
Ipratropium
Minor hepatotoxicity - Drug interactions (activates P450)
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.

21. Name four Antiarrhythmic drugs in class IA.
hypertension - angina - arrhythmias
Blocks Influenza A and RubellA; causes problems with the cerebellA
Quinidine - Amiodarone - Procainamide - Disopyramide
Bacitracin - Vancomycin

22. What are two clinical uses of Azathioprine?
Tetracycline - Doxycycline - Demeclocycline - Minocycline
Rare.
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)
Phenothiazine (neuroleptic - antiemetic).

23. Antiarrhythmic class II- mechanism?
Giardiasis - Amoebic dysentery (E. histolytica) - Bacterial vaginitis (Gardnerella vaginalis) - Trichomonas
Stimulates beta adrenergic receptors
blocking the beta adrenergic receptor leads to decreased cAMP - and decreased Ca2+ flux
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.

24. Esmolol - short or long acting?
block Na+ channels in the cortical collecting tubule
amphetamine and ephedrine
very short acting
In 4 half - lifes= (94%) T1/2 = (0.7x Vd)/CL

25. What is the lab value used to monitor the effectiveness of Heparin therapy?
Extended spectrum penicillin: certain Gram + bacteria and Gram - rods
G6PD deficient individuals
The PTT.
Methylzanthine; desired effect is bronchodilation - may cause bronchodilation by inhibiting phosphodiesterase - enzyme involved in degrading cAMP (controversial).

26. Which drug(s) cause this reaction: Gray baby syndrome?
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.
- Isoniazid
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome
- Chloramphenicol

27. What is a prerequisite for Acyclovir activation?
torsade de pointes
- Shifts the curve down - reduces Vmax
1. In liver - increases storage of glucose as glycogen. 2. In muscle - stimulates glycogen and protein synthesis - and K+ uptake. 3. In adipose tissue - facilitates triglyceride storage.
It must be Phosphorylated by Viral Thymidine Kinase

28. What are Methicillin - Nafcillin - and Dicloxacillin used for clinically?
1. Hot flashes 2. Ovarian enlargement 3. Multiple simultaneous pregnancies 4. Visual disturbances
increase AP duration - increase ERP - increase QT interval - for use When other arrhythmics fail
Succinylcholine
Staphlococcus aureus

29. What is the mechanism of Leuprolide?
Reversible block of histamine H2 receptors
Onchocerciasis ('river blindness'-- rIVER- mectin)
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
K+ wasting - metabolic alkalosis - hypotension - ototoxicity

30. What are the phases of succinylcholine neuromuscular blockade?
Pituitary hormone.
Phase 1 = prolonged depolarization - no antidote - effect potentiated by anticholinesterase; Phase 2 = repolarized but blocked - an anticholinesterase is the antidote for this phase.
proximal convoluted tubule
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.

31. What is the mechanism of action of the thrombolytics?
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.)
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors
Clavulanic acid
- Isoniazid

32. What is the category - desired effect - and possible mechanism of Theophylline in treating Asthma?
Inhibits cell wall synthesis ( binds to PBP3). A monobactam
Methylzanthine; desired effect is bronchodilation - may cause bronchodilation by inhibiting phosphodiesterase - enzyme involved in degrading cAMP (controversial).
Inhibit steroid synthesis - used in the treatment of polycystic ovarian syndrome to prevent hirsutism.
K+ wasting - metabolic alkalosis - hypotension - ototoxicity

33. What cholinergic inhibitor acts by directly inhibiting Ach release at the presynaptic terminal
- Methotrexate - 5 FU - 6 mercaptopurine
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.
Hypersensitivity reactions
Botulinum

34. Resistance mechanisms for Tetracycline
Rash - Pseudomembranous colitis
- Alkalinize urine & dialysis
Decreased uptake or Increased transport out of cell
Modification via Acetylation

35. Adverse effects of Guanethidine?
Neomycin
- Phase I (clinical tests) - Phase II - Phase III - PhaseIV (surveillance)
orthostatic and exercise hypotension - sexual dysfunction - diarrhea
Treatment of hypertension - especially with renal disease (lowers bp centrally - so flow is maintained to kidney).

36. What is the MOA of Aztreonam?
Inhibits cell wall synthesis ( binds to PBP3). A monobactam
Amphotericin B - Nystatin - Fluconazole/azoles
anuria - CHF
blocks SR Ca2+ channels

37. Triamterene and amiloride - mechanism?
block Na+ channels in the cortical collecting tubule
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic
Erectile dysfunction.
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.

38. Acetazolamide - site of action?
proximal convoluted tubule
- DNA intercalator - testicular & lymphomas - Pulmonary fibrosis mild myelosuppression.
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
1. In liver - increases storage of glucose as glycogen. 2. In muscle - stimulates glycogen and protein synthesis - and K+ uptake. 3. In adipose tissue - facilitates triglyceride storage.

39. Which drug(s) cause this reaction: Pulmonary fibrosis(3)?
RESPIre
- Bleomycin - amiodarone - busulfan
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time
Inhibits Viral DNA polymerase

40. List the mechanism - clinical use - & toxicity of Cisplatin.
- Alkalating agent - testicular - bladder - ovary -& lung - Nephrotoxicity & CN VIII damage.
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more
loop diuretics - spironolactone
Non - Nucleosides

41. Does Heparin have a long - medium - or short half life?
It must be Phosphorylated by Viral Thymidine Kinase
Short.
- Glucagon
Dopamine; causes its release from intact nerve terminals

42. Which drug(s) cause this reaction: Pseudomembranous colitis?
Hypersensitivity reactions
- N- acetylcystine
thick ascending limb
- Clindamycin

43. What are five advantages of Oral Contraceptives (synthetic progestins - estrogen)?
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
- Alkalating agent - testicular - bladder - ovary -& lung - Nephrotoxicity & CN VIII damage.
Antifungal.
K+ wasting - metabolic alkalosis - hypotension - ototoxicity

44. Name three Antiarrhythmic drugs in class IB.
Hemicholinium inhibits the transport of choline into the nerve - thus inhibiting formation of ACh.
To inhibit renal Dihydropeptidase I and decrease Imipenem inactivation in the renal tubules
Lidocaine - Mexiletine - Tocainide
G6PD deficient individuals

45. For Heparin What is the Lab value to monitor
Pyridoxine (B6) administration
aPTT (intrinsic pathway)
Severe Gram - rod infections.
hypertrichosis - pericardial effusion - reflex tachycardia - angina - salt retention

46. What are the nondepolarizing neuromuscular blocking drugs?
Tubocurarine - atracurium - mivacurium - pancuronium - vecuronium - rapacuronium
Penicillin - Cephalosporins - Vancomycin - Aminoglycosides - Fluoroquinolones - Metronidazole
- Halothane - Valproic acid - acetaminophen - Amantia phalloides
As an anticholinesterase it increases endogenous ACh and thus increases strength.

47. What type of gout is treated with Probenacid?
H2 antagonist
Chronic gout.
Decreases synthesis of Mycolic Acid
- Act on same receptor - Full has greater efficacy

48. Preferential action of the Ca2+ channel blockers at cardiac muscle?
cardiac muscle: Verapamil>Diltiazem>Nifedipine
Resistant Gram - infections
NO HYPERURICEMIA - NO SULFA AllERGY; same as furosemide otherwise
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.

49. K+ sparing diuretics - clinical use?
hyperaldosteronism - K+ depletion - CHF
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.
Inhibits CMV DNA polymerase
loop diuretics - thiazides

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

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