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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. Which of the following would atropine administration cause? Hypothermia - bradycardia - excess salivation - dry flushed skin - or diarrhea
Abortifacient.
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.
Penicillin - V
Oxygen

2. IV Penicillin
Treatment of hypertension - especially with renal disease (lowers bp centrally - so flow is maintained to kidney).
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis
Penicillin - G
Blocks Norepi - but not Dopamine

3. List the mechanism - clinical use - & toxicity of Tamoxifen.
- Estrogen receptor antagonist - Breast CA - increased endometrial CA risk
Digitoxin 168hrs Digoxin 40 hrs
Dermatophytes (tinea - ringworm)
TMP- SMZ (DOC) - aerosolized pentamidine

4. Antimicrobial prophylaxis for Meningococcal infection
- Glucocorticoid withdrawal
glaucoma - urinary alkalinization - metabolic alkalosis - altitude sickness
Rifampin (DOC) - minocycline
Prevents release of mediators from mast cells. Effective only for the prophylaxis of asthma. Not effective during an acute attack.

5. What is the category of drug names ending in - tidine (e.g. Cimetidine)
Disulfiram - like reaction with EtOH - Headache
H2 antagonist
Rifampin (DOC) - minocycline
Methylxanthine.

6. Acetazolamide - mechanism?
Chronic gout.
Does not cross
Spironolactone - Triamterene - Amiloride (the K+ STAys)
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.

7. How does angiotensin II affect NE release?
Blocking muscarinic receptors in the circular fibers of the eye - results in unopposed action of radial muscles to dilate.
- Alkalinize urine & dialysis
Sucralfate cannot work in the presence of antacids or H2 blockers because it requires an acidic environment to polymerize.
It acts presynaptically to increase NE release.

8. For Warfarin What is the Route of administration
Oral
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow
cardiac muscle: Verapamil>Diltiazem>Nifedipine
Acetylcholine esterase

9. Nifedipine has similar action to?
Nitrates
Gram + cocci - Haemophilus influenza - Enterobacter aerogenes - Neisseria species - P. mirabilis - E. coli - K. pneumoniae - Serratia marcescens ( HEN PEcKS )
Phosphorylation by a Viral Kinase
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels

10. Adverse effects of Losartan?
fetal renal toxicity - hyperkalemia
- Ammonium Chloride
- Acetaldehyde - Nausea - vomiting - headache - & hypotension
When pts have Low CD4+ (< 500 cells/cubic mm) or a High Viral Load

11. What are two conditions in Which COX-2 inhibitors might be used?
CMV - esp in Immunocompromised patients
Rheumatoid and osteoarthritis.
- Nitrate - hydroxocobalamin thiosulfate
Gentamicin - Neomycin - Amikacin - Tobramycin - Streptomycin

12. Mannitol - toxicity?
Antifungal.
- Atropine & pralidoxime
Beta -2 agonist.
pulmonary edema - dehydration

13. How does NE modulate its own release? What other neurotransmitter has this same effect?
Beta - lactamase cleavage of Beta - lactam ring
It acts presynaptically to increase NE release.
Large anionic polymer - acidic
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.

14. Side effects of Isoniazid (INH)?
Chagas' disease - American Trypanosomiasis (Trypanosoma cruzi)
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome
Headache - flushing - dyspepsia - blue - green color vision.
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility

15. How do we stop angina?
- Protamine
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time
YES
Inhibits cell wall mucopeptide formation - Bactericidal

16. What do Aminoglycosides require for uptake?
anuria - CHF
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
They inhibit reuptake of NE at the nerve terminal (as does cocaine).
Oxygen

17. What is a sign of toxicity with the use of thrombolytics?
Gram + cocci - Haemophilus influenza - Enterobacter aerogenes - Neisseria species - P. mirabilis - E. coli - K. pneumoniae - Serratia marcescens ( HEN PEcKS )
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.
Bleeding.
- N- acetylcystine

18. Antiarrhythmic class IV- toxicity?
constipation - flushing - edema - CV effects (CHF - AV block - sinus node depression) - and torsade de pointes (Bepridil)
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.
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.
Increases coumadin metabolism

19. Resistance mechanisms for Macrolides

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20. What is the mechanism of action of Warfarin (Coumadin)?
Epinephrine to treat anaphylaxis. Also useful if you have open angle glaucoma - asthma - or hypotension.
proarrhythmic
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone
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.

21. What are signs of Sildenafil (Viagra) toxicity?
Inhibt Assembly of new virus by Blocking Protease Enzyme
Headache - flushing - dyspepsia - blue - green color vision.
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.
AV nodal cells

22. Dobutamine used for the tx of shock acts on Which receptors
Cilastatin
Sulfonamides - Trimethoprim
Beta1 more than B2
Staphlococcus aureus

23. What are Fluoroquinolones indicated for? (3)
Neurotoxicity - Acute renal tubular necrosis
- Act on same receptor - Full has greater efficacy
1.Gram - rods of the Urinary and GI tracts (including Pseudomonas) 2.Neisseria 3. Some Gram + organisms
Polymyxin B - Polymyxin E

24. Mannitol - contraindications?
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.
- Infections - Trauma - Seizures - CO - Overdose - Metabolic - Alcohol (IT'S COMA)
- Shifts the curve to the right - increases Km
anuria - CHF

25. Describe the MOA of Interferons (INF)
1. Renal damage 2. Aplastic anemia 3. GI distress
- Isoniazid
Misoprostol is a PGE1 analog that increases the production and secretion of the gastic mucous barrier.
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis

26. Which drug(s) cause this reaction: Adrenocortical Insufficiency
Forms toxic metabolites in the bacterial cell - Bactericidal
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)
Binds Ergosterol - forms Membrane Pores that Disrupt Homeostatis
- Glucocorticoid withdrawal

27. What is the clinical use for Sildenafil (Viagra)?
Hypersensitivity reactions
- aminoglycosides - loop diuretics - cisplatin
Erectile dysfunction.
Ipratropium

28. What are three unwanted effects of Mifepristone?
Hypersensitivity reactions
Non - Nucleosides
reversible SLE- like syndrome
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain

29. What is the effect of the Glitazones in diabetes treatment?
Beta lactams - inhibit cell wall synthesis - Bactericidal
Well tolerated in general but occasionally - Nephrotoxicity - Ototoxicity - Thrombophlebitis - diffuse flushing='Red Man Syndrome'
decrease the slope of phase 4 - increase PR interval (the AV node is particularly sensitive)
Increase target cell response to insulin.

30. Cautions When using Amiodarone?
check PFTs - LFTs - and TFTs
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.
- Class III antiarrhythmics (sotalol) - class IA (quinidine)
Saquinavir - Ritonavir - Indinavir - Nelfinavir

31. What is the mechanism of action of Sildenafil (Viagra)?
Binds ergosterol - Disrupts fungal membranes
Inhibits cGMP phosphodiesterase - casuing increased cGMP - smooth muscle relaxation in the corpus cavernosum - increased blood flow - and penile erection.
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents
Gram + and Anerobes

32. List the specific antidote for this toxin: Arsenic (all heavy metals)
- Dimercaprol - succimer
Zidovudine (AZT) - Didanosine (ddI) - Zalcitabine (ddC) - Stavudine (d4T) - Lamivudine (3TC)
- Upper respiratory tract infections - pneumonias - STDs: Gram+ cocci (streptococcal infect in pts allergic to penicillin) - Mycoplasma - Legionella - Chlamydia - Neisseria
Increases mean - systolic - and diastolic bp - while there is little change in pulse pressure.

33. List the mechanism - clinical use - & toxicity of Cyclophosphamide.
Inhibits cGMP phosphodiesterase - casuing increased cGMP - smooth muscle relaxation in the corpus cavernosum - increased blood flow - and penile erection.
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.

34. What is the mechanism of action of the glucocorticoids?
Lipoxygenase
Mg = Must go to the bathroom.
constipation - flushing - edema - CV effects (CHF - AV block - sinus node depression) - and torsade de pointes (Bepridil)
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.

35. Why are albuterol and terbutaline effective in tx of acute asthmatic attacks?
penicillinase resistant
These B-2 agonists cause respiratory smooth muscle to relax.
Verapamil - Diltiazem - Bepridil
Competitive inibitor of progestins at progesterone receptors.

36. Antiarrhythmic class IB- effects?
- Antipsychotics
decrease AP duration - affects ischemic or depolarized Purkinje and ventricular system
Norepinephrine (Alpha1 -2 and beta 1)
Oxygen

37. In What population does Gray Baby Syndrome occur? Why?
local anesthetic. CNS stimulation or depression. CV depression.
Intrathecally
Protease Inhibitors and Reverse Transcriptase Inhibitors
Premature infants - because they lack UDP- glucuronyl transferase

38. Toxic side effects of the Azoles?
Hormone synthesis inhibition (Gynecomastia) - Liver dysfunction (Inhibits CYP450) - Fever - Chills
Resistant Gram - infections
Irreversibly inhibits H+/K+ ATPase in stomach parietal cells.
decrease conduction velocity - increase ERP - increase PR interval

39. Adverse effects of Hydralazine?
Captopril - Enalapril - Lisinopril
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention
- Metronidazole - certain cephalosporins - procarbazine - sulfonylureas
RESPIre

40. Explain potency in relation to full and partial agonists(2).
Resistant Gram - infections
- partial agonist can have increased - decreased - /A21or equal potency as full agonist. - Potency is an independent factor.
Hypersensitivity reactions
- Niacin - Ca++ channel blockers - adenosine - vancomycin

41. What is the category of drug names ending in - tropin (e.g. Somatotropin)
Inhibit viral DNA polymerase
Pituitary hormone.
Protease Inhibitors and Reverse Transcriptase Inhibitors
G6PD deficient individuals

42. What is Metronidazole used for clinically?
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium
Blastomyces - Coccidioides - Histoplasma - C. albicans; Hypercortisolism
Chronic anticoagulation.
Rifampin

43. What is the MOA of Aztreonam?
Inhibits cell wall synthesis ( binds to PBP3). A monobactam
is resistant
Protamine sulfate
Same as penicillin. Act as narrow spectrum antibiotics

44. Ca2+ channel blockers - mechanism?
Succinylcholine
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility
- EDTA - dimercaprol - succimer - & penicillamine
Early myocardial infarction.

45. What class of drug is echothiophate? What is its indication?
- Cimetidine - ketoconazole - grapefruit juice - erythromycin - INH - sulfonamides
anticholinesterase glaucoma
Doxycycline - because it is fecally eliminated
- Penicillin

46. What is the MOA for Nystatin?
Nephrotoxicity
Depolymerizes microtubules - impairing leukocyte chemotaxis and degranulation.
Binds ergosterol - Disrupts fungal membranes
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.

47. Your patient wants an effective drug to treat his motion sickness - What would you prescribe
Scopolamine
1. Hypoglycemia (more common with 2nd - generation drugs: glyburide - glipizide) 2. Disulfiram - like effects (not seen with 2nd - generation drugs).
toxic
- Cloazapine - carbamazapine - colchicine - PTU

48. What is the chemical name for Ganciclovir?
1. Antipyretic 2. Analgesic 3. Anti - inflammatory
Babiturate.
DHPG (dihydroxy-2- propoxymethyl guanine)
Flecainide - Encainide - Propafenone

49. What enzyme is responsible for the degredation of Ach
Acetylcholine esterase
pulmonary edema - dehydration
No - hemicholinum block the uptake of Choline and thus Ach synthesis
GI discomfort

50. Thiazides - site of action?
Clomiphene is a partial agonist at estrogen receptors in the pituitary gland. Prevents normal feedback inhibition and increses release of LH and FSHfrom the pituitary - Which stimulates ovulation.
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.
distal convoluted tubule (early)
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis