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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. Mannitol - mechanism?
cross - allergenic
Bethanechol - Neostigmine - physostigmine
Spironolactone - Triamterene - Amiloride (the K+ STAys)
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow

2. What are two Glitazones?
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.
Hypersensitivity reactions
1. Pioglitazone 2. Rosiglitazone.
Prevents the release of calcium from the sarcoplasmic reticulum of skeletal muscle.

3. What microorganisms are Aminoglycosides ineffective against?
- Chloramphenicol - benzene - NSAIDS - PTU - phenytoin
Constant FRACTION eliminated per unit time.(exponential)
RESPIre
Anaerobes

4. What is the mechanism of action of the Alpha - glucosidase inhibitors?
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.
Choline acetyltransferase
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
Same as penicillin. Extended spectrum antibiotics

5. Adverse effects of Captopril?
Erectile dysfunction.
torsade de pointes
fetal renal toxicity - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
Inhibits formation of Initiation Complex - causes misreading of mRNA - Bactericidal

6. Norepi feedbacks and inhibits the presynaptic receptor by What mechanism
Pregnant women - Children; because animal studies show Damage to Cartilage
1. Predisposes to viral infections and lymphoma 2. Nephrotoxic (preventable with mannitol diuresis)
Binding to the presynaptic alpha 2 release modulating receptors
Hypersensitivity reactions

7. Which diuretics cause alkalosis?
Ceftriaxone
troponin - tropomyosin system
loop diuretics - thiazides
1. Streptokinase 2. Urokinase 3. tPA (alteplase) - APSAC (anistreplase)

8. What is the main clinical use for the thrombolytics?
Early myocardial infarction.
Antifungal.
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.
sedation - depression - nasal stuffiness - diarrhea

9. How does botulinum toxin result in respiratory arrest?
Prevents the release of ACh - Which results in muscle paralysis.
- ED 50 is less than the Km (less than 50% of receptors)
Inhibit DNA Gyrase (topoisomerase II) - Bactericidal
- Infections - Trauma - Seizures - CO - Overdose - Metabolic - Alcohol (IT'S COMA)

10. What is the mechanism of action of Allopurinol used to treat chronic gout?
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.
Ld= (CpxVd)/F Cp=plasma conc. F= Bioaval.
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids

11. Furosemide - class and mechanism?
- A57Blue lines in gingiva & long bones - Encephalopathy & Foot drop - Abdominal colic / - Sideroblastic anemia
Malaria (P. falciparum)
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.
1. Renal damage 2. Aplastic anemia 3. GI distress

12. Decrease Digitoxin dose in renal failure?
AZT
NO
GI distress - Skin rash - and Seizures at high plasma levels
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone

13. What drugs target anticholinesterase
Neostigmine - pyridostigmine edrophonium - physostigmine echothiophate
G6PD deficient individuals
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased
- Flumazenil

14. Which drug(s) cause this reaction: Pulmonary fibrosis(3)?
- Bleomycin - amiodarone - busulfan
Lovastatin - Pravastatin - Simvastatin - Atorvastatin
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions
Triple sulfas or SMZ

15. What are Methicillin - Nafcillin - and Dicloxacillin used for clinically?
- Class III antiarrhythmics (sotalol) - class IA (quinidine)
Nonspecific beta - agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Adverse effect is tachycardia (Beta 1).
- polymyxins
Staphlococcus aureus

16. Describe Phase II metabolism in liver(3)?
- acetylation - glucuron. - & sulfation - Conjugation - Polar product
- Penicillin
As an anticholinesterase it increases endogenous ACh and thus increases strength.
loop diuretics - thiazides

17. Which drug(s) cause this reaction: Pseudomembranous colitis?
Staphlococcus aureus and Clostridium difficile (pseudomembranous colitis)
- Clindamycin
Epinephirine(Alpha1 -2 and Beta 1 -2)
- reduction - oxy - & hydrolysis - H2O sol. Polar product - P450

18. Ganciclovir associated toxicities?
- DNA intercalator - testicular & lymphomas - Pulmonary fibrosis mild myelosuppression.
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity
- ED 50 is less than the Km (less than 50% of receptors)
Pregnant women - Children; because animal studies show Damage to Cartilage

19. What enzyme is responsible for the degredation of Ach
reversible SLE- like syndrome
Acetylcholine esterase
Inhalational general anesthetic.
1. Taken daily 2. No protection against STDs 3. Raises triglycerides 4. Depression - weight gain - nausea - HTN 5. Hypercoagulable state

20. For Warfarin What is the Mechanism of action
Chronic gout.
- Airway - Breathing - Circulation - Dextrose (thiamine & narcan) - ABCD
Impairs the synthesis of vitamin K- dependent clotting factors
Pentavalent Antimony

21. What is the mechanism of action of Probenacid used to treat chronic gout?
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis
- Metronidazole - certain cephalosporins - procarbazine - sulfonylureas
Inhibits reabsorption of uric acid.
cyanide toxicity (releases CN)

22. Which drug(s) cause this reaction: Photosensitivity(3)?
1. Gastric ulceration 2. Bleeding 3. Hyperventilation 4. Reye's syndrome 5. Tinnitus (CN VIII)
Disulfiram - like reaction with EtOH - Headache
- Tetracycline - amiodarone - sulfonamides
propanolol - esmolol - metoprolol - atenolol - timolol

23. Which diuretics decrease urine Ca2+?
Digoxin=urinary Digitoxin=biliary
GI disturbances.
thiazides - amiloride
AZT

24. Guanethidine enhances the release of Norepi?
DHPG (dihydroxy-2- propoxymethyl guanine)
G6PD deficient individuals
No - it inhibits the release of Nor Epi
1. Weight gain 2. Hepatotoxicity (troglitazone)

25. What reversal agent could a Anes give to reverse the effects of Atropine
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention
sedation - positive Coombs' test
Bethanechol - Neostigmine - physostigmine
Liver

26. What is an additional side effect of Methicillin?
Interstitial nephritis
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more
Acetylcholine esterase
collecting ducts

27. Which drug(s) cause this reaction: Neuro and Nephrotoxic?
- polymyxins
Dermatophytes (tinea - ringworm)
Anaerobes
viral kinase

28. Which drug(s) cause this reaction: P450 inhibition(6)?
- Cimetidine - ketoconazole - grapefruit juice - erythromycin - INH - sulfonamides
Anaerobes
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)
proximal convoluted tubule - thin descending limb - and collecting duct

29. List the specific antidote for this toxin: Antimuscarinic (anticholinergic)
1. Bleeding 2. Teratogenicity 3. Drug - drug interactions
- Physostigmine salicylate
- Penicillamine
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic

30. Which drug(s) cause this reaction: Agranulocytosis (3)?
- reduction - oxy - & hydrolysis - H2O sol. Polar product - P450
- Alkalate DNA - Brain tumors - CNS toxicity
- Cloazapine - carbamazapine - colchicine - PTU
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.

31. Which drug increases Sys BP w/o affecting Pulse Pressure
No - hemicholinum block the uptake of Choline and thus Ach synthesis
Leukotrienes increasing bronchial tone.
Epinephrine
Systemic mycoses

32. What is the memory key for the effect of magnesium hydroxide overuse?
Mg = Must go to the bathroom.
- ACE inhibitors (Losartan>no cough)
Irreversibly inhibits H+/K+ ATPase in stomach parietal cells.
Penicillin - G

33. How do spare receptors effect the Km?
- reduction - oxy - & hydrolysis - H2O sol. Polar product - P450
1. Hot flashes 2. Ovarian enlargement 3. Multiple simultaneous pregnancies 4. Visual disturbances
Erectile dysfunction.
- ED 50 is less than the Km (less than 50% of receptors)

34. As an Anes you want to use a depolarizing neuromuscular blocking drug on your pt - What do you use
Rare.
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)
Succinylcholine
Phenothiazine (neuroleptic - antiemetic).

35. These drugs acts indirectly by releasing strored catecholamines in the presynaptic terminal
It inhibits release of NE.
Amphetamine and Ephedrine
Give an antichloinesterase - neostigmine - edrophonium - etc
Overdose produces hepatic necrosis; acetaminophen metablolite depletes glutathione and forms toxic tissue adducts in liver.

36. What are two mechanisms of action of Propythiouracil?
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.
Fever/Chills - Hypotension - Nephrotoxicity - Arrhythmias
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.
Chronic gout.

37. Which drug(s) cause this reaction: P450 induction(6)?
cholestyramine - colestipol
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine
bradycardia - AV block - CHF
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.

38. In What population does Gray Baby Syndrome occur? Why?
Premature infants - because they lack UDP- glucuronyl transferase
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)
Tricyclic antidepressant.
- Shifts the curve down - reduces Vmax

39. What is the lab value used to monitor the effectiveness of Warfarin therapy?
The PT.
- B51Naloxone / naltrexone (Narcan)
AV nodal cells
torsade de pointes

40. What are three possible toxicities of NSAID usage?
Dermatophytes (tinea - ringworm)
1. Renal damage 2. Aplastic anemia 3. GI distress
Activates antithrombin III
Can affect absorption - bioavailability - or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying.

41. What parasites are treated with Pyrantel Pamoate (more specific)?
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
CL= (rate of elimination of drug/ Plasma drug conc.)
- Hypersensitivity reactions - Hemolysis - Nephrotoxicity (tubulointerstitial nephritis) - Kernicterus in infants Displace other drugs from albumin (e.g. - warfarin)
Gram + - Gram - - Norcardia - Chlamydia

42. Which cancer drugs work at the level of proteins(2)?
- Vinca alkaloids(inhibit MT) - Paclitaxel
- Glucagon
- Oral Contraceptives
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.

43. What are the clinical indications for Azole therapy?
Systemic mycoses
- Protamine
- Alkalate DNA - Brain tumors - CNS toxicity
- Clindamycin

44. For Heparin What is the Site of action
RESPIre
Blood
AmOxicillin has greater Oral bioavailability
block Na+ channels in the cortical collecting tubule

45. Which individuals are predisposed to Sulfonamide - induced hemolysis?
- Lithium
G6PD deficient individuals
Because they require some residual islet function.
Diarrhea

46. What are two clinical uses of Azathioprine?
depresses ectopic pacemakers - especially in digoxin toxicity
Beta adrenergic receptors and Ca2+ channels (stimulatory)
bradycardia - AV block - CHF
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)

47. What is the MOA for Trimethoprim (TMP)?
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.
They inhibit reuptake of NE at the nerve terminal (as does cocaine).
Inhibits bacterial Dihydrofolate Reductase - Bacteriostatic
1. Addison's disease 2. Inflammation 3. Immune suppression 4. Asthma

48. What is the loading dose formula?
Ld= (CpxVd)/F Cp=plasma conc. F= Bioaval.
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine
effective in torsade de pointes and digoxin toxicity
Polymyxin B - Polymyxin E

49. Cocaine casues vasoconstriction and local anesthesia by What mechanism
Digitoxin 70% Digoxin 20-40%
Indirect agonist - uptake inhibitor
Flecainide - Encainide - Propafenone
Prevents the release of ACh - Which results in muscle paralysis.

50. What is the mecanism of action of the COX-2 inhibitors (celecoxib - rofecoxib)?
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome
Epinephrine to treat anaphylaxis. Also useful if you have open angle glaucoma - asthma - or hypotension.
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.