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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. What is the MOA of Ganciclovir?
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
Chronic gout.
torsade de pointes - excessive Beta block
Inhibits CMV DNA polymerase

2. What is the mechanism of action of the thrombolytics?
Neostigmine - pyridostigmine edrophonium - physostigmine echothiophate
Inhibit steroid synthesis - used in the treatment of polycystic ovarian syndrome to prevent hirsutism.
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.)
Paranteral (IV - SC)

3. What are three types of antacids and the problems that can result from their overuse?
Wide spectrum of systemic mycoses: Cryptococcus - Blastomyces - Coccidioides - Aspergillus - Histoplasma - Candida - Mucor
hyperchloremic metabolic acidosis - neuropathy - NH3 toxicity - sulfa allergy
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia
Interferes with microtubule function - disrupts mitosis - inhibits growth

4. Why is there a drop in systolic - mean - and diastolic bp with infusion of isoproterenol?
Vd= (Amt. of drug in body/ Plasma drug conc.)
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).
Pretreat with antihistamines and a slow infusion rate

5. What is combined with Ampicillin - Amoxicillin - Carbenicillin - Piperacillin - and Ticarcillin to enhance their spectrum?
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.
Clavulanic acid
Chagas' disease - American Trypanosomiasis (Trypanosoma cruzi)

6. List the mechanism - clinical use - & toxicity of Bleomycin.
Oral treatment of superficial infections
Interferes with microtubule function - disrupts mitosis - inhibits growth
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.
- DNA intercalator - testicular & lymphomas - Pulmonary fibrosis mild myelosuppression.

7. Aztreonam is not ________ with penicillins
cross - allergenic
Tendonitis and Tendon rupture
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.
Inhibits Viral DNA polymerase

8. What is Clindamycin used for clinically?
Prevents the release of Ca from SR of skeletal muscle
ACIDazolamide' causes acidosis
Anaerobic infections (e.g. - B. fragilis - C. perfringens)
- Triggers apoptosis - CLL - Hodgkin's in MOPP - Cushing - like syndrome

9. What is the category of drug names ending in - phylline (e.g. Theophylline)
- ACE inhibitors (Losartan>no cough)
- Niacin - Ca++ channel blockers - adenosine - vancomycin
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity
Methylxanthine.

10. How do you calculate maintenance dose?
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.
is resistant
Chronic Hepatitis A and B - Kaposi's Sarcoma
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.

11. Your patient wants an effective drug to treat his motion sickness - What would you prescribe
Penicillin.
Scopolamine
Sotalol - Ibutilide - Bretylium - Amiodarone
distal convoluted tubule (early)

12. List the specific antidote for this toxin: Beta Blockers
Long.
- Glucagon
Blocks Influenza A and RubellA; causes problems with the cerebellA
- Constant AMOUNT eliminated per unit time. - Etoh & ASA

13. What is the mechanism of action of Probenacid used to treat chronic gout?
Onchocerciasis ('river blindness'-- rIVER- mectin)
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
Spironolactone - Triamterene - Amiloride (the K+ STAys)
Inhibits reabsorption of uric acid.

14. MOA: Disrupt fungal cell membranes
GI side effects. (Indomethacin is less toxic - more commonly used.)
Foscarnet = pyroFosphate analog
Systemic mycoses
Amphotericin B - Nystatin - Fluconazole/azoles

15. List the specific antidote for this toxin: TPA & Streptokinase
- Aminocaproic acid
Ceftriaxone
Those patients who are taking nitrates.
fetal renal damage - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)

16. Adverse effects of beta - blockers?
impotence - asthma - CV effects (bradycardia - CHF - AV block) - CNS effects (sedation - sleep alterations)
- S- phase anti - metabolite folate analogue - Luk - Lymp - sarc - RA - & psoriasis / - Reversible myelosuppression
GI discomfort - Acute cholestatic hepatitis - Eosinophilia - Skin rashes
- Disulfram & also sulfonylureas - metronidazole

17. MOA: Bactericidal antibiotics
Penicillin - Cephalosporins - Vancomycin - Aminoglycosides - Fluoroquinolones - Metronidazole
- Vinca alkaloids(inhibit MT) - Paclitaxel
Cyclooxygenases (COX I - COX II).
- Normalize K+ - Lidocaine - & Anti - dig Mab

18. Name two organisms Vancomycin is commonly used for?
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol
Gentamicin - Neomycin - Amikacin - Tobramycin - Streptomycin
Staphlococcus aureus and Clostridium difficile (pseudomembranous colitis)
Tendonitis and Tendon rupture

19. Antiarrhythmic class IV- effects?
AZT
decrease conduction velocity - increase ERP - increase PR interval
VACUUM your Bed Room'
Acetaminophen has antipyretic and analgesic properties - but lacks anti - inflammatory properties.

20. For Heparin What is the Mechanism of action
- DNA intercalator - Hodgkin's - myeloma - sarcoma - and solid tumors - Cardiotoxicity & alopecia
Hypersensitivity reactions
Activates antithrombin III
- Alkalates DNA - CML - Pulmonary fibrosis hyperpigmentation

21. Why would you use pralidoxime after exposure to an organophosphate?
Abortifacient.
INH: Injures Neurons and Hepatocytes
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
Pralidoxime regenerates active cholinesterase.

22. Adverse effects of Minoxidil?
hypertrichosis - pericardial effusion - reflex tachycardia - angina - salt retention
Peptic ulcer disease.
Increases coumadin metabolism
ACE inhibitor.

23. List the mechanism - clinical use - & toxicity of 6 MP.
DOC in diagnosing and abolishing AV nodal arrhythmias
Choline acetyltransferase
- inhibits HGPRT (pur. Syn.) - Luk - Lymph
Due to the presence of a bulkier R group

24. What is a mnemonic to remember Amantadine's function?
Bacitracin - Vancomycin
Vibrio cholerae Acne Chlamydia Ureaplasma Urealyticum Mycoplasma pneumoniae Borrelia burgdorferi (Lyme's) Rickettsia Tularemia
Blocks Influenza A and RubellA; causes problems with the cerebellA
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.

25. Which drug(s) cause this reaction: P450 inhibition(6)?
Treatment of infertility.
impotence - asthma - CV effects (bradycardia - CHF - AV block) - CNS effects (sedation - sleep alterations)
Meningitis (H. influenza - N. meningitidis - S. pneumoniae) - Conserative treatment due to toxicities
- Cimetidine - ketoconazole - grapefruit juice - erythromycin - INH - sulfonamides

26. What drug is used to treat Trematode/fluke (e.g. - Schistosomes - Paragonimus - Clonorchis) or Cysticercosis
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.
Norepinephrine
Praziquantel
Hypersensitivity reactions

27. Furosemide - toxicity? (OH DANG)
Abortifacient.
Phenothiazine (neuroleptic - antiemetic).
dry mouth - sedation - severe rebound hypertension
Ototoxicity - Hypokalemia - Dehydration - Allergy (sulfa) - Nephritis (interstitial) - Gout

28. For Heparin What is the Route of administration
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens
Pregnant women - Children; because animal studies show Damage to Cartilage
Paranteral (IV - SC)
vasodilator - increases cGMP to induce smooth muscle relaxation (arterioles>veins; afterload reduction)

29. What are Polymyxins used for?
Resistant Gram - infections
Impairs the synthesis of vitamin K- dependent clotting factors
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis
Misoprostol is contraindicated in women of childbearing potential because it is an abortifacient.

30. Which drug(s) cause this reaction: Pseudomembranous colitis?
Botulinum
- Clindamycin
Gram + cocci - Haemophilus influenza - Enterobacter aerogenes - Neisseria species - P. mirabilis - E. coli - K. pneumoniae - Serratia marcescens ( HEN PEcKS )
Gentamicin - Neomycin - Amikacin - Tobramycin - Streptomycin

31. What parasites are treated with Pyrantel Pamoate (more specific)?
Blocking muscarinic receptors in the circular fibers of the eye - results in unopposed action of radial muscles to dilate.
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
Post - op and neurogenic ileus and urinary retention - myasthenia gravis - and reversal of neuromuscular junction blockade (post - op) through anticholinesterase activity.
Beta1 more than B2

32. Which drug(s) cause this reaction: Focal to massive hepatic necrosis (4)?
Dopamine
- Halothane - Valproic acid - acetaminophen - Amantia phalloides
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.
1. RNA pol inhibitor 2. Revs up P450 3. Red/orange body fluids 4. Rapid resistance if used alone

33. What are toxicities associated with Chloramphenicol?
- Corticosteroids - heparin
Paranteral (IV - SC)
Penicillin - V
Aplastic anemia (dose independent) - Gray Baby Syndrome

34. What is the mechanism of action of Clomiphene?
GI upset
Clomiphene is a partial agonist at estrogen receptors in the pituitary gland. Prevents normal feedback inhibition and increses release of LH and FSHfrom the pituitary - Which stimulates ovulation.
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased

35. Which H2 Blocker has the most toxic effects and What are they?
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.
Interstitial nephritis
Antileukotriene; blocks leukotriene receptors.
Pentavalent Antimony

36. List the mechanism - clinical use - & toxicity of Vincristine.

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37. List the mechanism - clinical use - & toxicity of 5 FU.
very short acting
- S- phase anti - metabolite Pyr analogue - Colon - solid tumors - & BCC/ - Irreversible myelosuppression
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity

38. Which drug(s) cause this reaction: Agranulocytosis (3)?
atropine - homatropine - tropicamide
- Cloazapine - carbamazapine - colchicine - PTU
Gemfibrozil - Clofibrate
local anesthetic. CNS stimulation or depression. CV depression.

39. Which drug(s) cause this reaction: Atropine - like side effects?
Keratin containing tissues - e.g. - nails
- Tricyclic antidepressants
severe hypertension - CHF
Inhibit DNA Gyrase (topoisomerase II) - Bactericidal

40. What is the definition of zero - order kinetics? Example?
Polymyxins
- Constant AMOUNT eliminated per unit time. - Etoh & ASA
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic
Epinephrine

41. Mannitol - toxicity?
pulmonary edema - dehydration
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents

42. Preferential action of the Ca2+ channel blockers at cardiac muscle?
- Fluoroquinolones
cardiac muscle: Verapamil>Diltiazem>Nifedipine
- Nitrate - hydroxocobalamin thiosulfate
Inhibits formation of Initiation Complex - causes misreading of mRNA - Bactericidal

43. Hydrochlorothiazide - toxicity? (hyperGLUC - plus others)
- DNA intercalator - Hodgkin's - myeloma - sarcoma - and solid tumors - Cardiotoxicity & alopecia
Blocks Peptide Bond formation at the 50S subunit - Bacteriostatic
Hypokalemic metabolic alkalosis - hyponatremia - hyperGlycemia - hyperLipidemia - hyperUricemia - hyperCalcemia - sulfa allergy.
Premature infants - because they lack UDP- glucuronyl transferase

44. K+- clinical use?
first dose orthostatic hypotension - dizziness - headache
- Formaldehyde & formic acid - severe acidosis & retinal damage
Imipenem
depresses ectopic pacemakers - especially in digoxin toxicity

45. For Warfarin What is the Duration of action
Teratogenic - Carcinogenic - Confusion - Headaches
new arrhythmias - hypotension
Chronic (weeks or months)
Rare.

46. How is Ribavirin used clinically?
for RSV
reversible SLE- like syndrome
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow
1. Antipyretic 2. Analgesic 3. Anti - inflammatory

47. Name four Antiarrhythmic drugs in class III.
Gentamicin - Neomycin - Amikacin - Tobramycin - Streptomycin
Sotalol - Ibutilide - Bretylium - Amiodarone
- Formaldehyde & formic acid - severe acidosis & retinal damage
1. Weight gain 2. Hepatotoxicity (troglitazone)

48. Can Heparin be used during pregnancy?
Well tolerated in general but occasionally - Nephrotoxicity - Ototoxicity - Thrombophlebitis - diffuse flushing='Red Man Syndrome'
- Estrogen receptor antagonist - Breast CA - increased endometrial CA risk
Muscarinic antagonist; competatively blocks muscarinic receptors - preventing bronchoconstriction.
Yes - it does not cross the placenta.

49. Which drug(s) cause this reaction: Tubulointerstitial Nephritis (5)?
1. Predisposes to viral infections and lymphoma 2. Nephrotoxic (preventable with mannitol diuresis)
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)
G6PD deficient individuals
- Dimercaprol - succimer

50. Hydralazine - toxicity?
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis
- DNA intercalator - Hodgkin's - myeloma - sarcoma - and solid tumors - Cardiotoxicity & alopecia
H2 antagonist
compensatory tachycardia - fluid retention - lupus - like syndrome