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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. Digoxin v. Digitoxin: protein binding?
Hemicholinium inhibits the transport of choline into the nerve - thus inhibiting formation of ACh.
- Oxalic acid - Acidosis & nephrotoxicity
Digitoxin 70% Digoxin 20-40%
- Metronidazole - certain cephalosporins - procarbazine - sulfonylureas

2. What anticholinesterase crosses the blood - brain - barrier?
physostigmine
- Hydralazine - Procainamide - INH - phenytoin
1. Antipyretic 2. Analgesic 3. Anti - inflammatory 4. Antiplatelet drug.
Systemic mycoses

3. What are three clinical uses of the NSAIDs?
Blood
Chagas' disease - American Trypanosomiasis (Trypanosoma cruzi)
1. Antipyretic 2. Analgesic 3. Anti - inflammatory
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.

4. Bretyllium - toxicity?
Rifampin - Ethambutol - Streptomycin - Pyrazinamide - Isoniazid (INH)
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs
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)
new arrhythmias - hypotension

5. Which Aminoglycoside is used for Bowel Surgery ?
Forms toxic metabolites in the bacterial cell - Bactericidal
Neomycin
Inhibits formation of Initiation Complex - causes misreading of mRNA - Bactericidal
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain

6. What is the mechanism of action of Aspirin?
cardiac depression - peripheral edema - flushing - dizziness - constipation
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
Methylation of rRNA near Erythromycin's ribosome binding site
Saquinavir - Ritonavir - Indinavir - Nelfinavir

7. What are two indirect acting adrenergic agonists?
Paranteral (IV - SC)
thick ascending limb
amphetamine and ephedrine
- Protamine

8. What is the mechanism of action of Omeprazole - Lansoprazole?
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.
bradycardia - AV block - CHF
Irreversibly inhibits H+/K+ ATPase in stomach parietal cells.
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.

9. List the specific antidote for this toxin: Antimuscarinic (anticholinergic)
- Physostigmine salicylate
Spironolactone - Triamterene - Amiloride (the K+ STAys)
- Hydralazine - Procainamide - INH - phenytoin
GI distress - Tooth discoloration and Inhibition of bone growth in children - Fanconi's syndrome - Photosensitivity

10. What is the MOA of Polymyxins?
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents
1. In liver - increases storage of glucose as glycogen. 2. In muscle - stimulates glycogen and protein synthesis - and K+ uptake. 3. In adipose tissue - facilitates triglyceride storage.
Binds to cyclophilins (peptidyl proline cis - trans isomerase) - blocking the differentiation and activation of T cells mainly by inhibiting the production of IL-2 and its receptor.
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.

11. What is the memory key for the effect of magnesium hydroxide overuse?
Quinidine - Amiodarone - Procainamide - Disopyramide
Mg = Must go to the bathroom.
- DNA intercalator - testicular & lymphomas - Pulmonary fibrosis mild myelosuppression.
Norepinephrine (Alpha1 -2 and beta 1)

12. List the specific antidote for this toxin: Salicylates
Only in limited amounts
1. Weight gain 2. Hepatotoxicity (troglitazone)
- Alkalinize urine & dialysis
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.

13. What are common toxicities associated with Tetracyclines?

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14. Which RT inhibitors cause Lactic Acidosis?
Neomycin
Nucleosides
depresses ectopic pacemakers - especially in digoxin toxicity
Anaerobic infections (e.g. - B. fragilis - C. perfringens)

15. What is the mecanism of action of Sucralfate?
Aluminum sucrose sulfate polymerizes in the acid environment of the stomach and selectively binds necrotic peptic ulcer tissue. Acts as a barrier to acid - pepsin - and bile.
- Vitamin K & fresh frozen plasma
vasodilator - increases cGMP to induce smooth muscle relaxation (arterioles>veins; afterload reduction)
- Alkalating agent - testicular - bladder - ovary -& lung - Nephrotoxicity & CN VIII damage.

16. Which of epi - norepi - or isoproterenol results in bradycardia?
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.
Norepinephrine
Rifampin - Ethambutol - Streptomycin - Pyrazinamide - Isoniazid (INH)
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)

17. What is the category of drug names ending in - tidine (e.g. Cimetidine)
H2 antagonist
cholestyramine - colestipol
sedation - positive Coombs' test
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions

18. What are four advantages of newer low - molecular - weight heparins (Enoxaparin)?
Antileukotriene; blocks synthesis by lipoxygenase.
Inhibit steroid synthesis - used in the treatment of polycystic ovarian syndrome to prevent hirsutism.
1. Better bioavailability 2. 2 to 4 times longer half life 3. Can be administered subcutaneously 4. Does not require laboratory monitoring
Nephrotoxicity (esp. with Cephalosporins) - Ototoxicity (esp. with Loop Diuretics)

19. What drug is given for Pneumocystis carinii prophylaxis?
fetal renal toxicity - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
They inhibit reuptake of NE at the nerve terminal (as does cocaine).
Benzathine penicillin G
Pentamidine

20. List the specific antidote for this toxin: TPA & Streptokinase
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.
- Aminocaproic acid
hyperkalemia - endocrine effects (gynecomastia - anti - androgen)
Amphotericin B - Nystatin - Fluconazole/azoles

21. What drug is used to diagnose myasthenia gravis?
Teratogenic - Carcinogenic - Confusion - Headaches
edrophonium (extremely short acting anticholinesterase)
Binding to the presynaptic alpha 2 release modulating receptors
- Tetracycline - amiodarone - sulfonamides

22. Why is there a drop in systolic - mean - and diastolic bp with infusion of isoproterenol?
Hemicholinium inhibits the transport of choline into the nerve - thus inhibiting formation of ACh.
- N- acetylcystine
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
Beta antagonist.

23. Do Tetracyclines penetrate the CNS?
all of them
- Chloramphenicol - benzene - NSAIDS - PTU - phenytoin
Only in limited amounts
Dermatophytes (tinea - ringworm)

24. How would hemicholinium treatment affect cholinergic neurons?
Hemicholinium inhibits the transport of choline into the nerve - thus inhibiting formation of ACh.
- reduction - oxy - & hydrolysis - H2O sol. Polar product - P450
CMV - esp in Immunocompromised patients
Hypersensitivity reactions

25. What is the clinical use for Penicillin?
hyperchloremic metabolic acidosis - neuropathy - NH3 toxicity - sulfa allergy
Activates antithrombin III
Bactericidal for: Gram + rod and cocci - Gram - cocci - and Spirochetes
Can affect absorption - bioavailability - or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying.

26. Triamterene and amiloride - mechanism?
decrease
Benzodiazepine.
block Na+ channels in the cortical collecting tubule
Aminoglycosides

27. What is the only depolarizing neuromuscular blocking agent?
Inhibit viral DNA polymerase
Succinylcholine
loop diuretics - spironolactone
hypertension - CHF - diabetic renal disease

28. What is the lab value used to monitor the effectiveness of Heparin therapy?
The PTT.
fetal renal toxicity - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
Same as penicillin. Act as narrow spectrum antibiotics
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.

29. Name three Antiarrhythmic drugs in class IB.
cross - allergenic
No - warfarin - unlike heparin - can cross the placenta.
Pseudomembranous colitis (C. difficile) - fever - diarrhea
Lidocaine - Mexiletine - Tocainide

30. Which antimuscarinic agents are used in producing mydriasis and cycloplegia?
Albuterol - tertbutaline
atropine - homatropine - tropicamide
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors
Spironolactone - Triamterene - Amiloride (the K+ STAys)

31. What is Ketoconazole specifically used for?
Blastomyces - Coccidioides - Histoplasma - C. albicans; Hypercortisolism
Gentamicin - Neomycin - Amikacin - Tobramycin - Streptomycin
1) Chloramphenical = bacteriostatic 2) Erythromycin = bacteriostatic 3) Lincomycin = bacteriostatic 4)cLindamycin = bacteriostatic
Useful in muscle paralysis during surgery or mechanical ventilation.

32. The MOA for Chloramphenicol is?
Lidocaine - Mexiletine - Tocainide
Inhibition of 50S peptidyl transferase - Bacteriostatic
Increased systolic and pulse pressure - decreased diastolic pressure - and little change in mean pressure.
- ED 50 is less than the Km (less than 50% of receptors)

33. What is the clincial use for Misoprostol?
Prevention of NSAID- induced peptic ulcers - maintains a PDA.
With an amino acid change of D- ala D- ala to D- ala D- lac
Modification via Acetylation - Adenylation - or Phosphorylation
local anesthetic. CNS stimulation or depression. CV depression.

34. MOA: Block cell wall synthesis by inhib. Peptidoglycan cross - linking (7)
In treatment of malignant hyperthermia - due to concomitant use of halothane and succinylcholine. Also in neuroleptic malignant syndrome - a toxicity of antipsychotic drugs.
Gram + cocci - Haemophilus influenza - Enterobacter aerogenes - Neisseria species - P. mirabilis - E. coli - K. pneumoniae - Serratia marcescens ( HEN PEcKS )
GI intolerance (nausea - diarrhea) - Hyperglycemia - Lipid abnormalities - Thrombocytopenia (Indinavir)
Penicillin - Ampicillin - Ticarcillin - Pipercillin - Imipenem - Aztreonam - Cephalosporins

35. What are four unwanted effects of Clomiphene use?
- Oral Contraceptives
- partial agonist can have increased - decreased - /A21or equal potency as full agonist. - Potency is an independent factor.
cholestyramine - colestipol
1. Hot flashes 2. Ovarian enlargement 3. Multiple simultaneous pregnancies 4. Visual disturbances

36. For Heparin What is the Duration of action
Corticosteroids; prevent production of leukotrienes from arachodonic acid by blocking phospholipase A2. Drugs of choice in a patient with status asthmaticus (in combination with albuterol.)
DOC in diagnosing and abolishing AV nodal arrhythmias
Forms toxic metabolites in the bacterial cell - Bactericidal
Acute (hours)

37. Which drug(s) cause this reaction: P450 inhibition(6)?
Tendonitis and Tendon rupture
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
- Cimetidine - ketoconazole - grapefruit juice - erythromycin - INH - sulfonamides
Heparin catalyzes the activation of antithrombin III.

38. Which drug(s) cause this reaction: Cinchonism (2)?
Cilastatin
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.
Keratin containing tissues - e.g. - nails
- Quinidine - quinine

39. Antiarrhythmic class IV- primary site of action?
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia
AV nodal cells
- Hydralazine - Procainamide - INH - phenytoin

40. What is the memory key for Isoniazid (INH) toxicity?
Babiturate.
INH: Injures Neurons and Hepatocytes
Penicillin - Cephalosporins - Vancomycin - Aminoglycosides - Fluoroquinolones - Metronidazole
- Ethosuxamide - sulfonamides - lamotrigine

41. 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.
Norepinephrine
- Estrogen receptor antagonist - Breast CA - increased endometrial CA risk
PT

42. What is the mechanism of action of Mifepristone (RU486)?
- Oxalic acid - Acidosis & nephrotoxicity
Competitive inibitor of progestins at progesterone receptors.
Hormone synthesis inhibition (Gynecomastia) - Liver dysfunction (Inhibits CYP450) - Fever - Chills
impotence - exacerbation of asthma - CV effects - CNS effects - may mask hypoclycemia

43. What is the mechanism of action of Colchicine used to treat acute gout?
Depolymerizes microtubules - impairing leukocyte chemotaxis and degranulation.
Nitrates
AluMINIMUM amount of feces.
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention

44. Furosemide increases the excretion of What ion?
VACUUM your Bed Room'
1. Antiandrogen 2. Nausea 3. Vomiting
Ca2+ (Loops Lose calcium)
- Protamine

45. What is the MOA for the Cephalosporins?
- N- acetylcystine
Beta lactams - inhibit cell wall synthesis - Bactericidal
Aminoglycosides - Tetracyclines
GI intolerance (nausea - diarrhea) - Hyperglycemia - Lipid abnormalities - Thrombocytopenia (Indinavir)

46. What are the products and their toxicities of the metabolism of Ethylene Glycol by / alcohol dehydrogenase?
Ganciclovir is more toxic to host enzymes
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.
- Oxalic acid - Acidosis & nephrotoxicity
Depolymerizes microtubules - impairing leukocyte chemotaxis and degranulation.

47. What drug is used to treat Trematode/fluke (e.g. - Schistosomes - Paragonimus - Clonorchis) or Cysticercosis
Praziquantel
- Methotrexate - 5 FU - 6 mercaptopurine
- B51Naloxone / naltrexone (Narcan)
Misoprostol is a PGE1 analog that increases the production and secretion of the gastic mucous barrier.

48. What are common toxic side effects of Sulfonamides? (5)
Dermatophytes (tinea - ringworm)
- Hypersensitivity reactions - Hemolysis - Nephrotoxicity (tubulointerstitial nephritis) - Kernicterus in infants Displace other drugs from albumin (e.g. - warfarin)
Ganciclovir is more toxic to host enzymes
- Normalize K+ - Lidocaine - & Anti - dig Mab

49. Which of these three drugs will cause a reflex bradycardia in your pt (Norepi - Epi - or Isoporterenol)
Gram + cocci - Haemophilus influenza - Enterobacter aerogenes - Neisseria species - P. mirabilis - E. coli - K. pneumoniae - Serratia marcescens ( HEN PEcKS )
Inhibits cGMP phosphodiesterase - casuing increased cGMP - smooth muscle relaxation in the corpus cavernosum - increased blood flow - and penile erection.
Norepinephrine
Blastomyces - Coccidioides - Histoplasma - C. albicans; Hypercortisolism

50. List the specific antidote for this toxin: Copper
orthostatic and exercise hypotension - sexual dysfunction - diarrhea
Acetylcholine esterase
- Penicillamine
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia