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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. What is the mechanism of action of Misoprostol?
1. Streptokinase 2. Urokinase 3. tPA (alteplase) - APSAC (anistreplase)
- Physostigmine salicylate
Misoprostol is a PGE1 analog that increases the production and secretion of the gastic mucous barrier.
Lidocaine - Mexiletine - Tocainide

2. Ryanodine - site of action?
blocks SR Ca2+ channels
- Infections - Trauma - Seizures - CO - Overdose - Metabolic - Alcohol (IT'S COMA)
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval
Give an antichloinesterase - neostigmine - edrophonium - etc

3. Why would a patient with cog - wheel rigidity and a shuffling gait be given benztropine?
Suramin
Parkinson patients benefit from antimuscarinic agents through its inhibitory action within the indirect pathway.
- Physostigmine salicylate
hypertrichosis - pericardial effusion - reflex tachycardia - angina - salt retention

4. Antiarrhythmic class IV- clinical use?
Diarrhea - Urination - Miosis - Bronchospasm - Bradycardia - Excitation of skeletal muscle and CNS - Lacrimation - Sweating - and Salivation = DUMBBELS; also abdominal cramping
prevention of nodal arrhythmias (SVT)
Norepinephrine
Cardiac glycoside (inotropic agent).

5. Antiarrhythmic class II- toxicity?
impotence - exacerbation of asthma - CV effects - CNS effects - may mask hypoclycemia
CL= (rate of elimination of drug/ Plasma drug conc.)
Lipoxygenase
YES

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

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7. What conditions are treated with Metronidazole?
- Clindamycin
- ED 50 is less than the Km (less than 50% of receptors)
Giardiasis - Amoebic dysentery (E. histolytica) - Bacterial vaginitis (Gardnerella vaginalis) - Trichomonas
Methylxanthine.

8. Acetazolamide causes?

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9. What is a possible toxicity of Alpha - glucosidase inhibitors used in type -2 diabetes?
GI disturbances.
Carbenicillin - Piperacillin - and Ticarcillin
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
Cephalosporins

10. What is a possible result of overdose of Acetaminophen?
Cyclooxygenases (COX I - COX II).
VACUUM your Bed Room'
Overdose produces hepatic necrosis; acetaminophen metablolite depletes glutathione and forms toxic tissue adducts in liver.
GI side effects. (Indomethacin is less toxic - more commonly used.)

11. For Warfarin What is the Route of administration
Nifedipine - Verapamil - Diltiazem
Oral
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.
Acetylcholinesterase; ACh is broken down into choline and acetate.

12. What is a possible toxicity of Ticlopidine - Clopidogrel usage?
is resistant
hyperkalemia - endocrine effects (gynecomastia - anti - androgen)
Neutropenia (ticlopidine); reserved for those who cannot tolerate aspirin.
Inhibit viral DNA polymerase

13. Are not penicillinase resistant
Teratogenic - Carcinogenic - Confusion - Headaches
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic
- Quinidine - quinine
Carbenicillin - Piperacillin - and Ticarcillin

14. What is the MOA of Foscarnet?
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
cardiac muscle: Verapamil>Diltiazem>Nifedipine
Inhibits Viral DNA polymerase
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.

15. What is the MOA for the Fluoroquinolones?
Acute gout.
cholestyramine - colestipol
Aminoglycosides
Inhibit DNA Gyrase (topoisomerase II) - Bactericidal

16. Which drug(s) cause this reaction: Cough?
- ACE inhibitors (Losartan>no cough)
Amphetamine and Ephedrine
Antileukotriene; blocks leukotriene receptors.
- Tetracycline - amiodarone - sulfonamides

17. Which drug(s) cause this reaction: Oto and Nephrotoxicity (3)?
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.
- aminoglycosides - loop diuretics - cisplatin
thick ascending limb

18. What are the clinical uses for 1st Generation Cephalosporins?
HSV - VZV - EBV - Mucocutaneous and Genital Herpes Lesions - Prophylaxis in Immunocompromised pts
Gram + cocci - Proteus mirabilis - E. coli - Klebsiella pneumoniae (PEcK)
Atropine would also block the receptors in the ciliary muscle - causing an impairment in accommodation (cycloplegia).
Rifampin

19. List five common glucocorticoids.
1. Gastric ulceration 2. Bleeding 3. Hyperventilation 4. Reye's syndrome 5. Tinnitus (CN VIII)
Nifedipine - Verapamil - Diltiazem
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone
1. Predisposes to viral infections and lymphoma 2. Nephrotoxic (preventable with mannitol diuresis)

20. What is combined with Ampicillin - Amoxicillin - Carbenicillin - Piperacillin - and Ticarcillin to enhance their spectrum?
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents
Clavulanic acid
No. Atropine is used to reduce urgency in mild cystitis. So it would aggravate the urinary retention.
1. Gastric ulceration 2. Bleeding 3. Hyperventilation 4. Reye's syndrome 5. Tinnitus (CN VIII)

21. Describe the MOA of Interferons (INF)
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis
Ld= (CpxVd)/F Cp=plasma conc. F= Bioaval.
Methylxanthine.
ACE inhibitor.

22. What is the mechanism of action of Aspirin?
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity
hypertension - CHF - diabetic renal disease
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
- Class III antiarrhythmics (sotalol) - class IA (quinidine)

23. How does resistance to Vancomycin occur?
With an amino acid change of D- ala D- ala to D- ala D- lac
1. Hypoglycemia (more common with 2nd - generation drugs: glyburide - glipizide) 2. Disulfiram - like effects (not seen with 2nd - generation drugs).
Atropine pts are suffering from Cholinestrase inhibitor poisining (Nerve gas/Organophosphate poisining)
scopolamine

24. What is the mechanism of action of the thrombolytics?
Hypersensitivity reactions
hypertension - CHF - diabetic renal disease
Directly of indirectly aid conversion of plasminogen to plasmin Which cleaves thrombin and fibrin clots. (It is claimed that tPA specifically converts fibrin - bound plasminogen to plasmin.)
Same as penicillin. Extended spectrum antibiotics

25. Which diuretics decrease urine Ca2+?
Epinephirine(Alpha1 -2 and Beta 1 -2)
No
thiazides - amiloride
Ganciclovir is more toxic to host enzymes

26. Decrease Digitoxin dose in renal failure?
- Alkalating agent - testicular - bladder - ovary -& lung - Nephrotoxicity & CN VIII damage.
Chronic gout.
Penicillin - G
NO

27. What are toxic side effects for Metronidazole?
Disulfiram - like reaction with EtOH - Headache
Hormone synthesis inhibition (Gynecomastia) - Liver dysfunction (Inhibits CYP450) - Fever - Chills
Bleeding.
Neostigmine - pyridostigmine edrophonium - physostigmine echothiophate

28. Which drug(s) cause this reaction: Cutaneous flushing (4)?
Ceftriaxone
- Niacin - Ca++ channel blockers - adenosine - vancomycin
Directly of indirectly aid conversion of plasminogen to plasmin Which cleaves thrombin and fibrin clots. (It is claimed that tPA specifically converts fibrin - bound plasminogen to plasmin.)
Heparin catalyzes the activation of antithrombin III.

29. What are the classic symptoms of cholinesterase inhibitor poisoning (parathion or other organophosphates)?
Foscarnet = pyroFosphate analog
Bismuth and Amoxicillin or Tetracycline; against Helobacter pylori
Inhibits DNA dependent RNA polymerase
Diarrhea - Urination - Miosis - Bronchospasm - Bradycardia - Excitation of skeletal muscle and CNS - Lacrimation - Sweating - and Salivation = DUMBBELS; also abdominal cramping

30. What is the clincial use for Misoprostol?
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.
Prevention of NSAID- induced peptic ulcers - maintains a PDA.
Oral
Prophylaxis for Influenza A - Rubella; Parkinson's disease

31. What side effect of using atropine to induce pupillary dilation would you expect?
Fever/Chills - Hypotension - Nephrotoxicity - Arrhythmias
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis
Atropine would also block the receptors in the ciliary muscle - causing an impairment in accommodation (cycloplegia).
1. Acarbose 2. Miglitol

32. What is the difference between the affinity for beta receptors between albuterol/terbutaline and dantroline?
H2 antagonist
Bethanechol - Neostigmine - physostigmine
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more
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.

33. What is the clinical use for Warfarin?
Milk or Antacids - because divalent cations inhibit Tetracycline absorption in the gut
Chronic anticoagulation.
Phosphorylation by a Viral Kinase
Quinidine - Amiodarone - Procainamide - Disopyramide

34. What enzyme is responsible for the production of Ach from Acetyl CoA and Choline
Choline acetyltransferase
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.
Slow - limited by half lives of clotting factors
Hormone synthesis inhibition (Gynecomastia) - Liver dysfunction (Inhibits CYP450) - Fever - Chills

35. What is a sign of toxicity with the use of thrombolytics?
Bleeding.
- Metronidazole - certain cephalosporins - procarbazine - sulfonylureas
Prophylaxis for Influenza A - Rubella; Parkinson's disease
Digitoxin>95% Digoxin 75%

36. Antimicrobial prophylaxis for PCP
Misoprostol is contraindicated in women of childbearing potential because it is an abortifacient.
HTN - CHF - calcium stone formation - nephrogenic DI.
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.
TMP- SMZ (DOC) - aerosolized pentamidine

37. What is the clinical use for Ampicillin and Amoxicillin?
severe hypertension - CHF
Extended spectrum penicillin: certain Gram + bacteria and Gram - rods
Fast vs. Slow Acetylators
ARF - shock - drug overdose - decrease intracranial/intraocular pressure

38. Verapamil has similar action to?
Erythromycin - Azithromycin - Clarithromycin
penicillinase resistant
Penicillin - Cephalosporins - Vancomycin - Aminoglycosides - Fluoroquinolones - Metronidazole
Beta Blockers

39. Antiarrhythmic class IV- primary site of action?
GI intolerance (nausea - diarrhea) - Hyperglycemia - Lipid abnormalities - Thrombocytopenia (Indinavir)
AV nodal cells
Prefers beta's at low doses - but at higher doses alpha agonist effects are predominantly seen.
Sildenafil fills the penis

40. What is the mechanism of action and clinical use of the antiandrogens Ketoconazole and Spironolactone?
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.
Inhibit steroid synthesis - used in the treatment of polycystic ovarian syndrome to prevent hirsutism.
- Quinidine - quinine

41. Oral Penicillin
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia
Small lipid - soluble molecule
Penicillin - V
- Constant AMOUNT eliminated per unit time. - Etoh & ASA

42. What is the MOA for Rifampin?
Inhibits DNA dependent RNA polymerase
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.
hyperkalemia - endocrine effects (gynecomastia - anti - androgen)
collecting ducts

43. What type of gout is treated with Probenacid?
proximal convoluted tubule
Inhibits Viral DNA polymerase
Chronic gout.
- Alkalating agent - testicular - bladder - ovary -& lung - Nephrotoxicity & CN VIII damage.

44. What is the memory key for Isoniazid (INH) toxicity?
Anaerobes
- Methotrexate - 5 FU - 6 mercaptopurine
sedation - sleep alterations
INH: Injures Neurons and Hepatocytes

45. List the mechanism - clinical use - & toxicity of Paclitaxel.
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.
Antileukotriene; blocks synthesis by lipoxygenase.
proarrhythmic
ACIDazolamide' causes acidosis

46. Classes of antihypertensive drugs?
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors
HTN - CHF - calcium stone formation - nephrogenic DI.
Teratogenic - Carcinogenic - Confusion - Headaches
fetal renal toxicity - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)

47. What cholinergic inhibitor acts by directly inhibiting Ach release at the presynaptic terminal
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
Botulinum
Same as penicillin. Extended spectrum antibiotics
Norepinephrine (Alpha1 -2 and beta 1)

48. What is the memory key to remember Which pathway (extrinsic vs. intrinsic) and Which lab value Warfarin affects?
- Normalize K+ - Lidocaine - & Anti - dig Mab
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.
Does not cross
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.

49. If a patient is given hexamethonium - What would happen to his/her heart rate?
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.
hypertension - angina - arrhythmias
CMV - esp in Immunocompromised patients
H2 antagonist

50. What is the MOA for Carbenicillin - Piperacillin - and Ticarcillin?
Leukotrienes increasing bronchial tone.
Muscarinic antagonist; competatively blocks muscarinic receptors - preventing bronchoconstriction.
Same as penicillin. Extended spectrum antibiotics
Topical and Oral - for Oral Candidiasis (Thrush)