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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.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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. Ibutilide - toxicity?
Digitoxin 168hrs Digoxin 40 hrs
Because they require some residual islet function.
Pituitary hormone.
torsade de pointes

2. What effect would atropine have on a patient with peptic ulcer disease?
Activates cholinergic receptors on bladder and bowel smooth muscle - alleviating post - op and neurogenic ileus and urinary retention.
Milk or Antacids - because divalent cations inhibit Tetracycline absorption in the gut
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).
- Triggers apoptosis - CLL - Hodgkin's in MOPP - Cushing - like syndrome

3. How can Vancomycin - induced 'Red Man Syndrome' be prevented?
- Act on same receptor - Full has greater efficacy
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine
Pretreat with antihistamines and a slow infusion rate
Erythromycin - Azithromycin - Clarithromycin

4. Adverse effects of Nifedipine - verapamil?
dizziness - flushing - constipation (verapamil) - nausea
Aplastic anemia (dose independent) - Gray Baby Syndrome
Hypersensitivity reactions
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)

5. What is the memory key for Metronidazole's clinical uses?
Chagas' disease - American Trypanosomiasis (Trypanosoma cruzi)
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.
Staphlococcus aureus
GET on the Metro

6. What is the effect of epinephrine infusion on bp and pulse pressure?
Increased systolic and pulse pressure - decreased diastolic pressure - and little change in mean pressure.
Neurotoxicity - Acute renal tubular necrosis
- Shifts the curve down - reduces Vmax
thick ascending limb

7. What are three types of antacids and the problems that can result from their overuse?
GI distress - Skin rash - and Seizures at high plasma levels
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia
Gram + - Gram - - Norcardia - Chlamydia
Aplastic anemia (dose independent) - Gray Baby Syndrome

8. What is the mechanism of action of Aspirin?
Interstitial nephritis
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
Anaerobic infections (e.g. - B. fragilis - C. perfringens)

9. Antimicrobial prophylaxis for Meningococcal infection
- Flumazenil
Prevents the release of Ca from SR of skeletal muscle
- Upper respiratory tract infections - pneumonias - STDs: Gram+ cocci (streptococcal infect in pts allergic to penicillin) - Mycoplasma - Legionella - Chlamydia - Neisseria
Rifampin (DOC) - minocycline

10. What is the mechanism of action of Probenacid used to treat chronic gout?
Flecainide - Encainide - Propafenone
bradycardia - AV block - CHF
Inhibits reabsorption of uric acid.
Overdose produces hepatic necrosis; acetaminophen metablolite depletes glutathione and forms toxic tissue adducts in liver.

11. List the mechanism - clinical use - & toxicity of Cyclophosphamide.
proarrhythmic
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity
AluMINIMUM amount of feces.

12. What enzyme is responsible for the degredation of Ach
Acetylcholine esterase
Inhibits Viral DNA polymerase
Praziquantel
cholestyramine - colestipol

13. What is Niclosamide used for?
Protease Inhibitors and Reverse Transcriptase Inhibitors
Pyridoxine (B6) administration
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis
hyperaldosteronism - K+ depletion - CHF

14. Explain pH dependent urinary drug elimination?
Rifampin (DOC) - minocycline
Increases mean - systolic - and diastolic bp - while there is little change in pulse pressure.
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.

15. Are penicillinase resistant
Gram + and Anerobes
Depolymerizes microtubules - impairing leukocyte chemotaxis and degranulation.
Methicillin - Nafcillin - and Dicloxacillin
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.

16. Does Ampicillin or Amoxicillin have a greater oral bioavailability?
- Methotrexate - 5 FU - 6 mercaptopurine
AmOxicillin has greater Oral bioavailability
Reserpine inhibits dopamine transport into vesicles - attenuating its conversion to NE by dopamine beta - hydroxylase.
check PFTs - LFTs - and TFTs

17. For Heparin What is the Structure
dizziness - flushing - constipation (verapamil) - nausea
Inhibits bacterial Dihydrofolate Reductase - Bacteriostatic
Large anionic polymer - acidic
Cilastatin

18. What is the MOA for Carbenicillin - Piperacillin - and Ticarcillin?
Slow - limited by half lives of clotting factors
Acute gout.
Same as penicillin. Extended spectrum antibiotics
- Ammonium Chloride

19. What is a mnemonic to remember Amantadine's function?
Blocks Influenza A and RubellA; causes problems with the cerebellA
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic
- Tetracycline

20. Mannitol - mechanism?
penicillinase resistant
Rifampin - Ethambutol - Streptomycin - Pyrazinamide - Isoniazid (INH)
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow

21. What enzyme is responsible for the production of Ach from Acetyl CoA and Choline
Staphlococcus aureus and Clostridium difficile (pseudomembranous colitis)
Choline acetyltransferase
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.
Same as penicillin. Extended spectrum antibiotics

22. What are two clinical uses of Azathioprine?
Immediate anticoagulation for PE - stroke - angina - MI - DVT.
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)

23. What two vasodilators require simultaneous treatment with beta blockers to prevent reflex tachycardia and diuretics to prevent salt retention?
Hydralazine and Minoxidil
blocking the beta adrenergic receptor leads to decreased cAMP - and decreased Ca2+ flux
1.Gram - rods of the Urinary and GI tracts (including Pseudomonas) 2.Neisseria 3. Some Gram + organisms
Interstitial nephritis

24. Which drug(s) cause this reaction: SLE- like syndrome?
hyperchloremic metabolic acidosis - neuropathy - NH3 toxicity - sulfa allergy
Nucleosides
- Hydralazine - Procainamide - INH - phenytoin
Hypersensitivity reactions

25. What are the Macrolides used for clinically?
Hypersensitivity reactions
Pituitary hormone.
- Upper respiratory tract infections - pneumonias - STDs: Gram+ cocci (streptococcal infect in pts allergic to penicillin) - Mycoplasma - Legionella - Chlamydia - Neisseria
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia

26. List the specific antidote for this toxin: Copper
- Nitrate - hydroxocobalamin thiosulfate
- Penicillamine
Fast vs. Slow Acetylators
Triple sulfas or SMZ

27. Which drug(s) cause this reaction: Gingival hyperplasia?
torsade de pointes - excessive Beta block
Aminoglycosides
Atropine would also block the receptors in the ciliary muscle - causing an impairment in accommodation (cycloplegia).
- Phenytoin

28. Which drug(s) cause this reaction: Aplastic anemia (5)?
Beta1 more than B2
- Chloramphenicol - benzene - NSAIDS - PTU - phenytoin
HSV - VZV - EBV - Mucocutaneous and Genital Herpes Lesions - Prophylaxis in Immunocompromised pts
- ED 50 is less than the Km (less than 50% of receptors)

29. List the specific antidote for this toxin: Salicylates
- Alkalinize urine & dialysis
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.
orthostatic and exercise hypotension - sexual dysfunction - diarrhea
The PTT.

30. How does angiotensin II affect NE release?
Beta lactams - inhibit cell wall synthesis - Bactericidal
Well tolerated in general but occasionally - Nephrotoxicity - Ototoxicity - Thrombophlebitis - diffuse flushing='Red Man Syndrome'
local anesthetic. CNS stimulation or depression. CV depression.
It acts presynaptically to increase NE release.

31. Adverse effects of Clonidine?
dry mouth - sedation - severe rebound hypertension
blocking the beta adrenergic receptor leads to decreased cAMP - and decreased Ca2+ flux
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids
AZT - to reduce risk of Fetal Transmission

32. How is Amphotericin B administered for fungal meningitis?
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased
Similar to cyclosporine; binds to FK- binding protein - inhibiting secretion of IL-2 and other cytokines.
TCA
Intrathecally

33. Your patient wants an effective drug to treat his motion sickness - What would you prescribe
Scopolamine
- Lithium
Inhalational general anesthetic.
Pregnant women - Children; because animal studies show Damage to Cartilage

34. Where does Griseofulvin deposit?
Keratin containing tissues - e.g. - nails
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.
Acute gout.
Tubocurarine - atracurium - mivacurium - pancuronium - vecuronium - rapacuronium

35. Antiarrhythmic Class III- effects?
increase AP duration - increase ERP - increase QT interval - for use When other arrhythmics fail
- Penicillin
GI discomfort - Acute cholestatic hepatitis - Eosinophilia - Skin rashes
RESPIre

36. K+- clinical use?
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.
penicillinase resistant
Pyridoxine (B6) administration
depresses ectopic pacemakers - especially in digoxin toxicity

37. What is an occasional side effect of Aztreonam?
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis
- ED 50 is less than the Km (less than 50% of receptors)
Stimulates beta adrenergic receptors
GI upset

38. What antimuscarinic agent is used in asthma and COPD?
Imipenem
Ipratropium
Neutropenia
Aminoglycosides - Tetracyclines

39. How does resistance to Vancomycin occur?
With an amino acid change of D- ala D- ala to D- ala D- lac
TMP- SMZ
Competitive inibitor of progestins at progesterone receptors.
Beta adrenergic receptors and Ca2+ channels (stimulatory)

40. What are two mechanisms of action of Propythiouracil?
AV nodal cells
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.
1.Gram - rods of the Urinary and GI tracts (including Pseudomonas) 2.Neisseria 3. Some Gram + organisms
Receptors = D1=D2>beta>alpha - thus increasing heart rate (beta) and blood pressure (alpha vasoconstriction) while maintaining kidney perfusion (dopamine receptors)

41. Beta Blockers - CNS toxicity?
sedation - sleep alterations
Pretreat with antihistamines and a slow infusion rate
Hydralazine and Minoxidil
Ceftriaxone

42. What is the category of drug names ending in - triptyline (e.g. Amitriptyline)
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity
- NaHCO3
- Metronidazole - certain cephalosporins - procarbazine - sulfonylureas
Tricyclic antidepressant.

43. Ryanodine - site of action?
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
fetal renal damage - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
blocks SR Ca2+ channels
Gram + and Anerobes

44. How can Isoniazid (INH)- induced neurotoxicity be prevented?
Pyridoxine (B6) administration
Severe Gram - rod infections.
GI discomfort - Acute cholestatic hepatitis - Eosinophilia - Skin rashes
propanolol - esmolol - metoprolol - atenolol - timolol

45. What cholinomimetic is useful in the diagnosis of Myasthenia Gravis
Edrophonium
Methicillin - Nafcillin - and Dicloxacillin
YES
Atropine pts are suffering from Cholinestrase inhibitor poisining (Nerve gas/Organophosphate poisining)

46. What are the indications for using amphetamine?

47. What is the lab value used to monitor the effectiveness of Warfarin therapy?
Penicillin.
The PT.
DHPG (dihydroxy-2- propoxymethyl guanine)
narcolepsy - obesity - and attention deficit disorder (I wouldn't recommend this)

48. What is the clinical utility of clonidine?
Treatment of hypertension - especially with renal disease (lowers bp centrally - so flow is maintained to kidney).
Bactericidal for: Gram + rod and cocci - Gram - cocci - and Spirochetes
pulmonary edema - dehydration
- Tamoxifen

49. What are three common NSAIDS other than Aspirin?
block Na+ channels in the cortical collecting tubule
Ibuprofen - Naproxen - and Indomethacin
- Dimercaprol - succimer
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).

50. How does a noncompetitive antagonist effect an agonist?
- Phenytoin
- Shifts the curve down - reduces Vmax
Increased systolic and pulse pressure - decreased diastolic pressure - and little change in mean pressure.
Indirect agonist - uptake inhibitor