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USMLE Step 1 Pharmacology

Subjects : health-sciences, usmle-step-1

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Answer 50 questions in 15 minutes.
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Match each statement with the correct term.
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1. Name two LPL stimulators.
Digitoxin>95% Digoxin 75%
Gemfibrozil - Clofibrate
TMP- SMZ
Acute gout.

2. 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.
decrease conduction velocity - increase ERP - increase PR interval
local anesthetic. CNS stimulation or depression. CV depression.
Resistant Gram - infections

3. Which diuretics increase urine Ca2+?
- Tricyclic antidepressants
loop diuretics - spironolactone
Verapamil - Diltiazem - Bepridil
No - hemicholinum block the uptake of Choline and thus Ach synthesis

4. Cocaine casues vasoconstriction and local anesthesia by What mechanism
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.
Dermatophytes (tinea - ringworm)
Indirect agonist - uptake inhibitor
- Ethanol - dialysis - & fomepizole

5. Adverse effects of Hydralazine?
K+ wasting - metabolic alkalosis - hypotension - ototoxicity
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention
Chronic anticoagulation.
Irreversibly inhibits H+/K+ ATPase in stomach parietal cells.

6. What are two toxicities associated with Cyclosporine?
1. Predisposes to viral infections and lymphoma 2. Nephrotoxic (preventable with mannitol diuresis)
dry mouth - sedation - severe rebound hypertension
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.
Prevents release of mediators from mast cells. Effective only for the prophylaxis of asthma. Not effective during an acute attack.

7. What is the MOA for Metronidazole?
Gemfibrozil - Clofibrate
Succinylcholine
Succinylcholine
Forms toxic metabolites in the bacterial cell - Bactericidal

8. Are not penicillinase resistant
Carbenicillin - Piperacillin - and Ticarcillin
proarrhythmic
Nevirapine - Delavirdine
Sulfonamides - Trimethoprim

9. Acetazolamide - toxicity?
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
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
As an anticholinesterase it increases endogenous ACh and thus increases strength.
hyperchloremic metabolic acidosis - neuropathy - NH3 toxicity - sulfa allergy

10. What are the clinical uses for Imipenem/cilastatin?
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
atropine - homatropine - tropicamide
Gram + cocci - Gram - rods - and Anerobes
Protamine sulfate

11. What is the formula for Clearance (CL)
CL= (rate of elimination of drug/ Plasma drug conc.)
Increases coumadin metabolism
Norepinephrine
Beta - lactamase cleavage of Beta - lactam ring

12. Common toxicities associated with Griseofulvin?
Erythromycin - Azithromycin - Clarithromycin
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels
Teratogenic - Carcinogenic - Confusion - Headaches
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.

13. Which drug(s) cause this reaction: Fanconi's syndrome?
is resistant
- Tetracycline
GI upset - Superinfections - Skin rashes - Headache - Dizziness
CMV Retinitis in IC pts When Ganciclovir fails

14. List the mechanism - clinical use - & toxicity of Doxorubicin.

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15. Adverse effects of Reserpine?
Prevention of NSAID- induced peptic ulcers - maintains a PDA.
Inhibits cell wall synthesis ( binds to PBP3). A monobactam
Activates antithrombin III
sedation - depression - nasal stuffiness - diarrhea

16. How do you calculate maintenance dose?
- ED 50 is less than the Km (less than 50% of receptors)
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity
cardiac depression - peripheral edema - flushing - dizziness - constipation
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.

17. Why is Cilastatin administered with Imipenem?
Triple sulfas or SMZ
- Dimercaprol - succimer
To inhibit renal Dihydropeptidase I and decrease Imipenem inactivation in the renal tubules
Captopril - Enalapril - Lisinopril

18. What is the definition of zero - order kinetics? Example?
- Constant AMOUNT eliminated per unit time. - Etoh & ASA
bradycardia - AV block - CHF
- Shifts the curve to the right - increases Km
Edrophonium

19. What are Aminoglycosides used for clinically?
- B51Naloxone / naltrexone (Narcan)
1.Gram - rods of the Urinary and GI tracts (including Pseudomonas) 2.Neisseria 3. Some Gram + organisms
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased
Severe Gram - rod infections.

20. What are five possible toxic effects of Aspirin therapy?

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21. Name common Polymyxins
Primaquine
edrophonium (extremely short acting anticholinesterase)
Impairs the synthesis of vitamin K- dependent clotting factors
Polymyxin B - Polymyxin E

22. Which drug(s) cause this reaction: Focal to massive hepatic necrosis (4)?
- Halothane - Valproic acid - acetaminophen - Amantia phalloides
Treatment of infertility.
Enterobacter
1. Weight gain 2. Hepatotoxicity (troglitazone)

23. Name two bile acid resins.
The only local anesthetic with vasoconstrictive properties.
Quinidine - Amiodarone - Procainamide - Disopyramide
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval
cholestyramine - colestipol

24. Which drug(s) cause this reaction: Cardiac toxicity?
dizziness - flushing - constipation (verapamil) - nausea
- aminoglycosides - loop diuretics - cisplatin
Tricyclic antidepressant.
- Daunorubicin & Doxorubicin

25. Name three Antiarrhythmic drugs in class IC.
Tubocurarine - atracurium - mivacurium - pancuronium - vecuronium - rapacuronium
Penicillin.
- Bleomycin - amiodarone - busulfan
Flecainide - Encainide - Propafenone

26. Antiarrhythmic class IV- clinical use?
1.Gram - rods of the Urinary and GI tracts (including Pseudomonas) 2.Neisseria 3. Some Gram + organisms
prevention of nodal arrhythmias (SVT)
Methylation of rRNA near Erythromycin's ribosome binding site
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine

27. What is the clinical use of Tacrolimus (FK506)?
Chronic Hepatitis A and B - Kaposi's Sarcoma
Binds Ergosterol - forms Membrane Pores that Disrupt Homeostatis
Potent immunosuppressive used in organ transplant recipients.
Antimetabolite derivative of 6- mercaptopurine that interferes with the metablolism and synthesis of nucleic acid.

28. What is the mechanism of action of Acetaminophen?
For serious - Gram + multidrug - resistant organisms
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.
local anesthetic. CNS stimulation or depression. CV depression.
No - warfarin - unlike heparin - can cross the placenta.

29. Amprotericin B ___________ the BBB
NO HYPERURICEMIA - NO SULFA AllERGY; same as furosemide otherwise
Nonspecific beta - agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Adverse effect is tachycardia (Beta 1).
Does not cross
glaucoma - urinary alkalinization - metabolic alkalosis - altitude sickness

30. Which drug(s) cause this reaction: Thrombotic complications?
Beta 2 agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Use during acute exacerbation.
fetal renal toxicity - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
GET on the Metro
- Oral Contraceptives

31. Antiarrhythmic class IC- effects?
NO AP duration effect. useful in V- tach that progresses to V- fib and in intractable SVT Last RESORT
Teratogenic - Carcinogenic - Confusion - Headaches
Sotalol - Ibutilide - Bretylium - Amiodarone
Onchocerciasis ('river blindness'-- rIVER- mectin)

32. Which RT inhibitors cause a Rash?
- Ammonium Chloride
Liver
Non - Nucleosides
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.

33. What are three unwanted effects of Mifepristone?
H2 antagonist
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome
- Daunorubicin & Doxorubicin
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain

34. Explain differences between full and partial agonists(2).
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
1)Binds penicillin - binding proteins 2) Blocks transpeptidase cross - linking of cell wall 3) Activates autolytic enzymes
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.
- Act on same receptor - Full has greater efficacy

35. Bretyllium - toxicity?
new arrhythmias - hypotension
Cilastatin
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.
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.

36. Which antimuscarinic agents are used in producing mydriasis and cycloplegia?
atropine - homatropine - tropicamide
thick ascending limb
GI distress - Tooth discoloration and Inhibition of bone growth in children - Fanconi's syndrome - Photosensitivity
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels

37. What are the products and their toxicities of the metabolism of Methanol by / alcohol dehydrogenase?
thiazides - amiloride
- Formaldehyde & formic acid - severe acidosis & retinal damage
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.
- Vitamin K & fresh frozen plasma

38. What is the category of drug names ending in - tropin (e.g. Somatotropin)
decrease
Inhibit DNA Gyrase (topoisomerase II) - Bactericidal
- Tamoxifen
Pituitary hormone.

39. What is the possible mechanism and effect of Metformin in treating diabetes?
- Dimercaprol - succimer
In 4 half - lifes= (94%) T1/2 = (0.7x Vd)/CL
toxic
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels

40. What are the major toxic side effects of the Cephalosporins?
1) Hypersensitivity reactions 2) Increased nephrotoxicity of Aminoglycosides 3) Disulfiram - like reaction with ethanol (those with a methylthiotetrazole group - e.g. - cefamandole)
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine
1. Better bioavailability 2. 2 to 4 times longer half life 3. Can be administered subcutaneously 4. Does not require laboratory monitoring
Gentamicin - Neomycin - Amikacin - Tobramycin - Streptomycin

41. What is the mechanism of Leuprolide?
Inhibits cGMP phosphodiesterase - casuing increased cGMP - smooth muscle relaxation in the corpus cavernosum - increased blood flow - and penile erection.
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine
TMP- SMZ
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

42. What enzyme is responsible for the production of Ach from Acetyl CoA and Choline
Headache - flushing - dyspepsia - blue - green color vision.
Choline acetyltransferase
dizziness - flushing - constipation (verapamil) - nausea
Inhibits DNA dependent RNA polymerase

43. Which Aminoglycoside is used for Bowel Surgery ?
Yes - it does not cross the placenta.
Suramin
Neomycin
Quinolones

44. What organisms does Griseofulvin target?
Dermatophytes (tinea - ringworm)
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia
1. Meningococcal carrier state 2. Chemoprophylaxis in contacts of children with H. influenzae type B

45. List the mechanism - clinical use - & toxicity of Etoposide.
- Penicillamine
Forms toxic metabolites in the bacterial cell - Bactericidal
- Isoniazid
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.

46. What sympathomimetic would you not prescribe for hypotension in a pt with renal artery sclerosis.
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain
anticholinesterase glaucoma
Norepinephrine (Alpha1 -2 and beta 1)
Rash - Pseudomembranous colitis

47. Preferential action of the Ca2+ channel blockers at vascular smooth muscle?
Phase 1 = prolonged depolarization - no antidote - effect potentiated by anticholinesterase; Phase 2 = repolarized but blocked - an anticholinesterase is the antidote for this phase.
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.
vascular sm. Mus.: Nifedipine>Diltiazem>Verapamil
No - hemicholinum block the uptake of Choline and thus Ach synthesis

48. MOA: Block protein synthesis at 50s subunit
- reduction - oxy - & hydrolysis - H2O sol. Polar product - P450
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
- aminoglycosides - loop diuretics - cisplatin

49. What is the mechanism of action of the glucocorticoids?
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity
Beta antagonist.
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.
vasodilator - increases cGMP to induce smooth muscle relaxation (arterioles>veins; afterload reduction)

50. What are two conditions in Which COX-2 inhibitors might be used?
Rheumatoid and osteoarthritis.
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine
Quinidine - Amiodarone - Procainamide - Disopyramide