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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 the products and their toxicities of the metabolism of Ethylene Glycol by / alcohol dehydrogenase?
viral kinase
Triple Therapy' 2 Nucleoside RT Inhibitors with a Protease Inhibitor
Chronic (weeks or months)
- Oxalic acid - Acidosis & nephrotoxicity

2. Why does NE result in bradycardia?
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
collecting ducts
Lipoxygenase
severe hypertension - CHF

3. What enzymes are inhibited by NSAIDs - acetaminophen and COX II inhibitors?
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
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.
DOC in diagnosing and abolishing AV nodal arrhythmias
Cyclooxygenases (COX I - COX II).

4. What is the mechanism of action of Warfarin (Coumadin)?
Minor hepatotoxicity - Drug interactions (activates P450)
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.
- Normalize K+ - Lidocaine - & Anti - dig Mab
- inhibits HGPRT (pur. Syn.) - Luk - Lymph

5. What patients are at risk for life threatening hypotension When taking Sildenafil (Viagra)?
Those patients who are taking nitrates.
- A57Blue lines in gingiva & long bones - Encephalopathy & Foot drop - Abdominal colic / - Sideroblastic anemia
Pretreat with antihistamines and a slow infusion rate
In treatment of malignant hyperthermia - due to concomitant use of halothane and succinylcholine. Also in neuroleptic malignant syndrome - a toxicity of antipsychotic drugs.

6. What is the MOA of Aztreonam?
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.
- Glucagon
Inhibits cell wall synthesis ( binds to PBP3). A monobactam
Gram + - Gram - - Norcardia - Chlamydia

7. What is the MOA for the Fluoroquinolones?
Bactericidal for: Gram + rod and cocci - Gram - cocci - and Spirochetes
decrease AP duration - affects ischemic or depolarized Purkinje and ventricular system
Beta - lactam antibiotics
Inhibit DNA Gyrase (topoisomerase II) - Bactericidal

8. Which of these three drugs will cause a reflex bradycardia in your pt (Norepi - Epi - or Isoporterenol)
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.
Norepinephrine
CMV - esp in Immunocompromised patients
GI disturbances.

9. MOA: Disrupt fungal cell membranes
Amphotericin B - Nystatin - Fluconazole/azoles
Cyclooxygenases (COX I - COX II).
Ganciclovir is more toxic to host enzymes
It inhibits release of NE.

10. Which drug(s) cause this reaction: Cinchonism (2)?
Same as penicillin. Act as narrow spectrum antibiotics
Teratogenic - Carcinogenic - Confusion - Headaches
- Quinidine - quinine
Vibrio cholerae Acne Chlamydia Ureaplasma Urealyticum Mycoplasma pneumoniae Borrelia burgdorferi (Lyme's) Rickettsia Tularemia

11. K+ sparing diuretics - clinical use?
Binds Ergosterol - forms Membrane Pores that Disrupt Homeostatis
hyperaldosteronism - K+ depletion - CHF
Sucralfate cannot work in the presence of antacids or H2 blockers because it requires an acidic environment to polymerize.
Beta antagonist.

12. How are Sulfonamides employed clinically?
Because they require some residual islet function.
Foscarnet = pyroFosphate analog
Gram + - Gram - - Norcardia - Chlamydia
scopolamine

13. List the specific antidote for this toxin: Iron
Tricyclic antidepressant.
hypertrichosis - pericardial effusion - reflex tachycardia - angina - salt retention
AluMINIMUM amount of feces.
- Deferoxamine

14. Digitalis - site of action?
Neutropenia (ticlopidine); reserved for those who cannot tolerate aspirin.
Na/K ATPase
No - hemicholinum block the uptake of Choline and thus Ach synthesis
For serious - Gram + multidrug - resistant organisms

15. How would you treat African Trypanosomiasis (sleeping sickness)?
Malaria (P. falciparum)
- acetylation - glucuron. - & sulfation - Conjugation - Polar product
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.
Suramin

16. What is the MOA for Ampicillin and Amoxicillin?
torsade de pointes
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity
Same as penicillin. Extended spectrum antibiotics
Enterobacter

17. What is the major toxic side effect of Penicillin?
new arrhythmias - hypotension
Onchocerciasis ('river blindness'-- rIVER- mectin)
Phenothiazine (neuroleptic - antiemetic).
Hypersensitivity reactions

18. What drug is used during the pregnancy of an HIV+ mother? - Why?
hyperaldosteronism - K+ depletion - CHF
Ipratropium
Acts as a wide spectrum carbapenem
AZT - to reduce risk of Fetal Transmission

19. Name the common Non - Nucleoside Reverse Transcriptase Inhibitors
Nevirapine - Delavirdine
increase AP duration - increase ERP - increase QT interval - for use When other arrhythmics fail
No - warfarin - unlike heparin - can cross the placenta.
Chagas' disease - American Trypanosomiasis (Trypanosoma cruzi)

20. What organism is Imipenem/cilastatin the Drug of Choice for?
Atropine would also block the receptors in the ciliary muscle - causing an impairment in accommodation (cycloplegia).
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)
Enterobacter
Methicillin - Nafcillin - and Dicloxacillin

21. How does angiotensin II affect NE release?
Penicillin - Cephalosporins - Vancomycin - Aminoglycosides - Fluoroquinolones - Metronidazole
Only in limited amounts
It acts presynaptically to increase NE release.
Decreases synthesis of Mycolic Acid

22. What is action of insulin in the liver - in muscle - and in adipose tissue?
Flecainide - Encainide - Propafenone
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.
- Alkalating agents+cisplatin - Doxorubicin+Dactinomycin - Bleomycin - Etoposide
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome

23. What are two Alpha - glucosidase inhibitors?
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
1. Acarbose 2. Miglitol
Chronic Hepatitis A and B - Kaposi's Sarcoma
proarrhythmic

24. How is Griseofulvin used clinically?
troponin - tropomyosin system
Oral treatment of superficial infections
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.
Norepinephrine

25. How is Ganciclovir activated?
Quinolones
-100% oxygen - hyperbaric
thick ascending limb
Phosphorylation by a Viral Kinase

26. Which drug(s) cause this reaction: Atropine - like side effects?
- Tricyclic antidepressants
cardiac depression - peripheral edema - flushing - dizziness - constipation
Inhibt Assembly of new virus by Blocking Protease Enzyme
Increased systolic and pulse pressure - decreased diastolic pressure - and little change in mean pressure.

27. Describe first - order kinetics?
- Tricyclic antidepressants
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia
- Steroids - Tamoxifen
Constant FRACTION eliminated per unit time.(exponential)

28. Toxicities associated with Acyclovir?
YES
Cephalosporins
CMV Retinitis in IC pts When Ganciclovir fails
Delirium - Tremor - Nephrotoxicity

29. List the specific antidote for this toxin: Tricyclic antidepressants
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.
- NaHCO3
Binds to cyclophilins (peptidyl proline cis - trans isomerase) - blocking the differentiation and activation of T cells mainly by inhibiting the production of IL-2 and its receptor.

30. What is the MOA of Amantadine?
- Flumazenil
Blocks viral penetration/uncoating; may act to buffer the pH of the endosome
Blocking muscarinic receptors in the circular fibers of the eye - results in unopposed action of radial muscles to dilate.
cardiac muscle: Verapamil>Diltiazem>Nifedipine

31. List the specific antidote for this toxin: Beta Blockers
- Glucagon
TMP- SMZ (DOC) - aerosolized pentamidine
Depolymerizes microtubules - impairing leukocyte chemotaxis and degranulation.
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)

32. Antimicrobial prophylaxis for a history of recurrent UTIs
1. Renal damage 2. Aplastic anemia 3. GI distress
TMP- SMZ
Leukotrienes increasing bronchial tone.
Digoxin=urinary Digitoxin=biliary

33. What type of gout is treated with Allopurinol?
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia
- Alkalinize urine & dialysis
Chronic gout.
Dobutamine has more of an affintiy for beta -1 than beta -2 - and is used for treating heart failure and shock. Albuterol and terbutaline is the reverse - and is used in treatment of acute asthma.

34. Common toxicities associated with Fluoroquinolones?
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia
Penicillin.
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.
GI upset - Superinfections - Skin rashes - Headache - Dizziness

35. What microorganisms are clinical indications for Tetracycline therapy?

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36. What is Clindamycin used for clinically?
Anaerobic infections (e.g. - B. fragilis - C. perfringens)
- Glucagon
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis
Same as penicillin. Extended spectrum antibiotics

37. How is Amantadine used clinically?

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38. What is the category of drug names ending in - phylline (e.g. Theophylline)
Keratin containing tissues - e.g. - nails
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.
Methylxanthine.

39. What are five disadvantages of Oral Contraceptives (synthetic progestins - estrogen)?
Captopril - Enalapril - Lisinopril
Antifungal.
- Formaldehyde & formic acid - severe acidosis & retinal damage
1. Taken daily 2. No protection against STDs 3. Raises triglycerides 4. Depression - weight gain - nausea - HTN 5. Hypercoagulable state

40. Which RT inhibitors cause a Rash?
Same as penicillin. Extended spectrum antibiotics
Topical and Oral - for Oral Candidiasis (Thrush)
- MT polymerization inhibitor(M phase) - MOPP - lymphoma - Willm's & choriocarcinoma - neurotoxicity and myelosuppression
Non - Nucleosides

41. Adverse effects of Nifedipine - verapamil?
1.Gram - rods of the Urinary and GI tracts (including Pseudomonas) 2.Neisseria 3. Some Gram + organisms
Benzodiazepine.
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.
dizziness - flushing - constipation (verapamil) - nausea

42. MOA: Block mRNA synthesis
Cyclooxygenases (COX I - COX II).
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.
Rifampin
Ceftriaxone

43. What is the category of drug names ending in - tidine (e.g. Cimetidine)
Peptic ulcer disease.
H2 antagonist
1. Phospholipase A2 is prevented from releasing arachidonic acid 2. Decreases protein synthesis thus lowering amount of Cyclooxygenase enzymes
Neutropenia

44. What are two clinical uses of Azathioprine?
cardiac depression - peripheral edema - flushing - dizziness - constipation
Oral
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)
Nephrotoxicity (esp. with Cephalosporins) - Ototoxicity (esp. with Loop Diuretics)

45. If a patient is given hexamethonium - What would happen to his/her heart rate?
CMV - esp in Immunocompromised patients
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.
It would increase to ~ 100 beats/min. Both sympathetic and vagal stimulation would be knocked out - but the SA node has an intrinsic pace of 100 beats/min - Which is normally checked by vagal stimulation.
G6PD deficient individuals

46. What is the enzyme inhibited - the effect of this inhibition - and the clinical use of the antiandrogren Finasteride?
Finasteride inhibits 5 Alpha - reductase - this decreases the conversion of testosterone to dihydrotestosterone - useful in BPH
Long.
- Alkalates DNA - CML - Pulmonary fibrosis hyperpigmentation
collecting ducts

47. Which drug(s) cause this reaction: Neuro and Nephrotoxic?
- polymyxins
No
Triple Therapy' 2 Nucleoside RT Inhibitors with a Protease Inhibitor
- Shifts the curve down - reduces Vmax

48. Antiarrhythmic class IV- clinical use?
Treatment of hypertension - especially with renal disease (lowers bp centrally - so flow is maintained to kidney).
- Aminocaproic acid
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).
prevention of nodal arrhythmias (SVT)

49. What are four Sulfonylureas?
Foscarnet = pyroFosphate analog
Staphlococcus aureus
Atropine would also block the receptors in the ciliary muscle - causing an impairment in accommodation (cycloplegia).
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide

50. What is the mechanism of action of Probenacid used to treat chronic gout?
Inhibits reabsorption of uric acid.
1. Buffalo hump 2. Moon facies 3. Truncal obesity 4. Muscle wasting 5. Thin skin 6. Easy bruisability 7. Osteoporosis 8. Adrenocortical atrophy 9. Peptic ulcers
- Airway - Breathing - Circulation - Dextrose (thiamine & narcan) - ABCD
1. Hypoglycemia (more common with 2nd - generation drugs: glyburide - glipizide) 2. Disulfiram - like effects (not seen with 2nd - generation drugs).