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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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1. Amprotericin B ___________ the BBB
Hypersensitivity reactions
Does not cross
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.
- Hypersensitivity reactions - Hemolysis - Nephrotoxicity (tubulointerstitial nephritis) - Kernicterus in infants Displace other drugs from albumin (e.g. - warfarin)

2. IV Penicillin
1. Hypoglycemia (more common with 2nd - generation drugs: glyburide - glipizide) 2. Disulfiram - like effects (not seen with 2nd - generation drugs).
Penicillin - G
- Fluoroquinolones
Increase target cell response to insulin.

3. What are three clinical uses of the NSAIDs?
- Tetracycline
1. Antipyretic 2. Analgesic 3. Anti - inflammatory
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
For serious - Gram + multidrug - resistant organisms

4. Mannitol - clinical use?
ARF - shock - drug overdose - decrease intracranial/intraocular pressure
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.
- S- phase anti - metabolite Pyr analogue - Colon - solid tumors - & BCC/ - Irreversible myelosuppression
Gram + cocci - Gram - rods - and Anerobes

5. What is the effect of norepinephrine on bp and pulse pressure?
Decreases synthesis of Mycolic Acid
Increases mean - systolic - and diastolic bp - while there is little change in pulse pressure.
Pentavalent Antimony
Hypersensitivity reactions

6. What are the products and their toxicities of the metabolism of Ethylene Glycol by / alcohol dehydrogenase?
Hydralazine and Minoxidil
- Oxalic acid - Acidosis & nephrotoxicity
Pralidoxime regenerates active cholinesterase.
Foscarnet = pyroFosphate analog

7. How do you calculate maintenance dose?
It must be Phosphorylated by Viral Thymidine Kinase
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.
Dopamine
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.

8. While at a tail gait party - you bite into a sandwich that a yellow jacket is also enjoying. Knowing your allergy to this creature - What should you do?
Epinephrine to treat anaphylaxis. Also useful if you have open angle glaucoma - asthma - or hypotension.
- Nitrate - hydroxocobalamin thiosulfate
decrease the slope of phase 4 - increase PR interval (the AV node is particularly sensitive)
Rifampin (DOC) - minocycline

9. What is the MOA for the Tetracyclines?
- Tetracycline
- Flumazenil
Disulfiram - like reaction with EtOH - Headache
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic

10. Which drug(s) cause this reaction: Photosensitivity(3)?
Saquinavir - Ritonavir - Indinavir - Nelfinavir
- Tetracycline - amiodarone - sulfonamides
- polymyxins
Diarrhea - Urination - Miosis - Bronchospasm - Bradycardia - Excitation of skeletal muscle and CNS - Lacrimation - Sweating - and Salivation = DUMBBELS; also abdominal cramping

11. Adverse effects of Minoxidil?
hypertrichosis - pericardial effusion - reflex tachycardia - angina - salt retention
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.
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity
Digitoxin>95% Digoxin 75%

12. For Heparin What is the Lab value to monitor
sedation - depression - nasal stuffiness - diarrhea
aPTT (intrinsic pathway)
fetal renal damage - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
Binds to the Pyrophosphate Binding Site of the enzyme

13. What is the most common cause of Pt noncompliance with Macrolides?
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
- Tetracycline
It inhibits release of NE.
GI discomfort

14. Resistance mechanisms for Aminoglycosides
GI distress - Tooth discoloration and Inhibition of bone growth in children - Fanconi's syndrome - Photosensitivity
- Bleomycin - amiodarone - busulfan
- Oral Contraceptives
Modification via Acetylation - Adenylation - or Phosphorylation

15. What is the memory key for Metronidazole's clinical uses?
Babiturate.
cross - allergenic
INH: Injures Neurons and Hepatocytes
GET on the Metro

16. What is the mechanism of action of Colchicine used to treat acute gout?
Bacitracin - Vancomycin
cross - allergenic
Depolymerizes microtubules - impairing leukocyte chemotaxis and degranulation.
torsade de pointes

17. For Heparin What is the Ability to inhibit coagulation in vitro
Yes
Imipenem
Diarrhea
AluMINIMUM amount of feces.

18. What is the loading dose formula?
Ld= (CpxVd)/F Cp=plasma conc. F= Bioaval.
Nitrates
new arrhythmias - hypotension
hypertension - angina - arrhythmias

19. Common toxicities associated with Fluoroquinolones?
Inhibition of 50S peptidyl transferase - Bacteriostatic
- Vinca alkaloids(inhibit MT) - Paclitaxel
GI upset - Superinfections - Skin rashes - Headache - Dizziness
cholestyramine - colestipol

20. What cholinomimetics might your pt be taking for his glaucoma
Interferes with microtubule function - disrupts mitosis - inhibits growth
Due to the presence of a bulkier R group
These B-2 agonists cause respiratory smooth muscle to relax.
Carbachol - pilocarpine - physostigmine - echothiophate

21. Adverse effects of ganglionic blockers?
sedation - positive Coombs' test
1. Gastric ulceration 2. Bleeding 3. Hyperventilation 4. Reye's syndrome 5. Tinnitus (CN VIII)
severe orthostatic hypotension - blurred vision - constipation - sexual dysfunction
Inhibit Ergosterol synthesis

22. What is the MOA of Griseofulvin?
As an anticholinesterase it increases endogenous ACh and thus increases strength.
Interferes with microtubule function - disrupts mitosis - inhibits growth
Verapamil - Diltiazem - Bepridil
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents

23. Which drug(s) cause this reaction: Gingival hyperplasia?
1. Antipyretic 2. Analgesic 3. Anti - inflammatory 4. Antiplatelet drug.
Ipratropium
- Phenytoin
- Steroids - Tamoxifen

24. What is the major side effect for Ampicillin and Amoxicillin?
Hypersensitivity reactions
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
vasodilator - increases cGMP to induce smooth muscle relaxation (arterioles>veins; afterload reduction)
Competitive inibitor of progestins at progesterone receptors.

25. What is the mechanism of Azathioprine?
Antimetabolite derivative of 6- mercaptopurine that interferes with the metablolism and synthesis of nucleic acid.
Binding to the presynaptic alpha 2 release modulating receptors
Lidocaine - Mexiletine - Tocainide
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.

26. Which RT inhibitor causes Megaloblastic Anemia?
- N- acetylcystine
Gentamicin - Neomycin - Amikacin - Tobramycin - Streptomycin
AZT
Short.

27. What are the clinical indications for Azole therapy?
Systemic mycoses
- Triggers apoptosis - CLL - Hodgkin's in MOPP - Cushing - like syndrome
Cephalosporins
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow

28. Clonidine is the preferred sym pathomimetic tx of HTN in pts with renal disease - why??
TCA
Aminoglycosides - Tetracyclines
hyperkalemia - endocrine effects (gynecomastia - anti - androgen)
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow

29. Acetazolamide - mechanism?
pulmonary edema - dehydration
Antileukotriene; blocks leukotriene receptors.
Hemolytic anemia
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.

30. Which drug(s) cause this reaction: Neuro and Nephrotoxic?
Pituitary hormone.
Inhibits DNA dependent RNA polymerase
Misoprostol is contraindicated in women of childbearing potential because it is an abortifacient.
- polymyxins

31. Hydralazine - class and mechanism?
pulmonary edema - dehydration
vasodilator - increases cGMP to induce smooth muscle relaxation (arterioles>veins; afterload reduction)
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
- Alkalinize urine & dialysis

32. Preferential action of the Ca2+ channel blockers at vascular smooth muscle?
Cimetidine is a potent inhibitor of P450; it also has an antiandrogenic effect and decreases renal excretion of creatinine. Other H2 blockers are relatively free of these effects.
Stimulates beta adrenergic receptors
AluMINIMUM amount of feces.
vascular sm. Mus.: Nifedipine>Diltiazem>Verapamil

33. Ca2+ channel blockers - clinical use?
Immediate anticoagulation for PE - stroke - angina - MI - DVT.
Depolymerizes microtubules - impairing leukocyte chemotaxis and degranulation.
hypertension - angina - arrhythmias
- Ammonium Chloride

34. Ibutilide - toxicity?
Captopril - Enalapril - Lisinopril
torsade de pointes
For serious - Gram + multidrug - resistant organisms
Tubocurarine - atracurium - mivacurium - pancuronium - vecuronium - rapacuronium

35. How would you treat African Trypanosomiasis (sleeping sickness)?
- Ammonium Chloride
Aminoglycosides - Tetracyclines
Pseudomonas species and Gram - rods
Suramin

36. What would be the effect on blood pressure with infusion of the alpha -2 agonist clonidine?
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.
first dose orthostatic hypotension - dizziness - headache
G6PD deficient individuals
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.

37. What is a possible toxicity of Ticlopidine - Clopidogrel usage?
Hormone synthesis inhibition (Gynecomastia) - Liver dysfunction (Inhibits CYP450) - Fever - Chills
Hypersensitivity reactions
Neutropenia (ticlopidine); reserved for those who cannot tolerate aspirin.
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic

38. Furosemide - clinical use?
Beta antagonist.
Blocking muscarinic receptors in the circular fibers of the eye - results in unopposed action of radial muscles to dilate.
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia

39. K+ sparing diuretics - toxicity?
PT
hyperkalemia - endocrine effects (gynecomastia - anti - androgen)
- Airway - Breathing - Circulation - Dextrose (thiamine & narcan) - ABCD
Ipratropium

40. What is the mechanism of action of Omeprazole - Lansoprazole?
1. Renal damage 2. Aplastic anemia 3. GI distress
Irreversibly inhibits H+/K+ ATPase in stomach parietal cells.
thiazides - amiloride
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.

41. ACE inhibitors - toxicity?
Penicillin.
fetal renal damage - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
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.
Enterobacter

42. Classes of antihypertensive drugs?
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors
Fever/Chills - Hypotension - Nephrotoxicity - Arrhythmias
Chronic anticoagulation.
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic

43. For Warfarin What is the Site of action
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.
Liver
Milk or Antacids - because divalent cations inhibit Tetracycline absorption in the gut

44. How can the toxic effects of TMP be ameliorated?
cross - allergenic
Inhibit viral DNA polymerase
- Triggers apoptosis - CLL - Hodgkin's in MOPP - Cushing - like syndrome
With supplemental Folic Acid

45. What is the mechanism of action of the glucocorticoids?
prevention of nodal arrhythmias (SVT)
K+ wasting - metabolic alkalosis - hypotension - ototoxicity
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.
Misoprostol is a PGE1 analog that increases the production and secretion of the gastic mucous barrier.

46. What are the clinical indications for bethanechol?
Hypokalemic metabolic alkalosis - hyponatremia - hyperGlycemia - hyperLipidemia - hyperUricemia - hyperCalcemia - sulfa allergy.
Carbenicillin - Piperacillin - and Ticarcillin
- polymyxins
Activates cholinergic receptors on bladder and bowel smooth muscle - alleviating post - op and neurogenic ileus and urinary retention.

47. How is Chloramphenical used clinically?
Tubocurarine - atracurium - mivacurium - pancuronium - vecuronium - rapacuronium
DHPG (dihydroxy-2- propoxymethyl guanine)
AZT - to reduce risk of Fetal Transmission
Meningitis (H. influenza - N. meningitidis - S. pneumoniae) - Conserative treatment due to toxicities

48. Name common Polymyxins
- Fluoroquinolones
Impairs the synthesis of vitamin K- dependent clotting factors
Polymyxin B - Polymyxin E
Overdose produces hepatic necrosis; acetaminophen metablolite depletes glutathione and forms toxic tissue adducts in liver.

49. How do spare receptors effect the Km?
Buy AT 30 - CELL at 50'
- ED 50 is less than the Km (less than 50% of receptors)
Acute (hours)
DOC in diagnosing and abolishing AV nodal arrhythmias

50. Antimicrobial prophylaxis for Syphilis
Scopolamine
Pyridoxine (B6) administration
Butyrophenone (neuroleptic).
Benzathine penicillin G