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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. Your patient wants an effective drug to treat his motion sickness - What would you prescribe
hyperchloremic metabolic acidosis - neuropathy - NH3 toxicity - sulfa allergy
1.Gram - rods of the Urinary and GI tracts (including Pseudomonas) 2.Neisseria 3. Some Gram + organisms
Scopolamine
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.

2. Antiarrhythmic Class III- effects?
increase AP duration - increase ERP - increase QT interval - for use When other arrhythmics fail
Bleeding.
Gram + cocci - Haemophilus influenza - Enterobacter aerogenes - Neisseria species - P. mirabilis - E. coli - K. pneumoniae - Serratia marcescens ( HEN PEcKS )
Methylation of rRNA near Erythromycin's ribosome binding site

3. What are Fluoroquinolones indicated for? (3)
- Dimercaprol - succimer
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval
Epinephirine(Alpha1 -2 and Beta 1 -2)
1.Gram - rods of the Urinary and GI tracts (including Pseudomonas) 2.Neisseria 3. Some Gram + organisms

4. What is clinical use for Carbenicillin - Piperacillin - and Ticarcillin?
- Alkalating agents+cisplatin - Doxorubicin+Dactinomycin - Bleomycin - Etoposide
Pseudomonas species and Gram - rods
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.
ARF - shock - drug overdose - decrease intracranial/intraocular pressure

5. How are Sulfonamides employed clinically?
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain
Chronic Hepatitis A and B - Kaposi's Sarcoma
Hypokalemic metabolic alkalosis - hyponatremia - hyperGlycemia - hyperLipidemia - hyperUricemia - hyperCalcemia - sulfa allergy.
Gram + - Gram - - Norcardia - Chlamydia

6. How is Griseofulvin used clinically?
- Ethanol - dialysis - & fomepizole
Increases mean - systolic - and diastolic bp - while there is little change in pulse pressure.
As an anticholinesterase it increases endogenous ACh and thus increases strength.
Oral treatment of superficial infections

7. What is the mechanism of action of Misoprostol?
viral kinase
Misoprostol is a PGE1 analog that increases the production and secretion of the gastic mucous barrier.
Small lipid - soluble molecule
GI distress - Tooth discoloration and Inhibition of bone growth in children - Fanconi's syndrome - Photosensitivity

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

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9. How is Foscarnet used clinically?
CMV Retinitis in IC pts When Ganciclovir fails
1. Antiandrogen 2. Nausea 3. Vomiting
Systemic mycoses
Cryptococcal meningitis in AIDS patients and Candidal infections of all types

10. What is the category of drug names ending in - cycline (e.g. Tetracycline)
Antibiotic - protein synthesis inhibitor.
Aminoglycosides
With an amino acid change of D- ala D- ala to D- ala D- lac
cyanide toxicity (releases CN)

11. What is the receptor affinity and clinical use of isoproterenol?
Inhibits cGMP phosphodiesterase - casuing increased cGMP - smooth muscle relaxation in the corpus cavernosum - increased blood flow - and penile erection.
It affects beta receptors equally and is used in AV heart block (rare).
Spironolactone - Triamterene - Amiloride (the K+ STAys)
It must be Phosphorylated by Viral Thymidine Kinase

12. Why is Cilastatin administered with Imipenem?
To inhibit renal Dihydropeptidase I and decrease Imipenem inactivation in the renal tubules
Antileukotriene; blocks leukotriene receptors.
Delirium - Tremor - Nephrotoxicity
Amphotericin B - Nystatin - Fluconazole/azoles

13. What conditions are treated with Metronidazole?
- Formaldehyde & formic acid - severe acidosis & retinal damage
ACIDazolamide' causes acidosis
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide
Giardiasis - Amoebic dysentery (E. histolytica) - Bacterial vaginitis (Gardnerella vaginalis) - Trichomonas

14. Beta Blockers - site of action?
depresses ectopic pacemakers - especially in digoxin toxicity
1. Phospholipase A2 is prevented from releasing arachidonic acid 2. Decreases protein synthesis thus lowering amount of Cyclooxygenase enzymes
Reserpine inhibits dopamine transport into vesicles - attenuating its conversion to NE by dopamine beta - hydroxylase.
Beta adrenergic receptors and Ca2+ channels (stimulatory)

15. How do you treat coma in the ER (4)?
- Airway - Breathing - Circulation - Dextrose (thiamine & narcan) - ABCD
Interstitial nephritis
hypertension - CHF - diabetic renal disease
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic

16. When is HIV therapy initiated?
When pts have Low CD4+ (< 500 cells/cubic mm) or a High Viral Load
- S- phase anti - metabolite Pyr analogue - Colon - solid tumors - & BCC/ - Irreversible myelosuppression
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis
vascular sm. Mus.: Nifedipine>Diltiazem>Verapamil

17. MOA: Block protein synthesis at 50s subunit
Same as penicillin. Act as narrow spectrum antibiotics
Binding to the presynaptic alpha 2 release modulating receptors
ACIDazolamide' causes acidosis
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)

18. Isopoterenol was given to a patient with a developing AV block - why?
It must be Phosphorylated by Viral Thymidine Kinase
Antileukotriene; blocks leukotriene receptors.
Clavulanic acid
Stimulates beta adrenergic receptors

19. What is the mecanism of action - effective period - and ineffective period of use for Cromolyn in treating Asthma?
Prevents release of mediators from mast cells. Effective only for the prophylaxis of asthma. Not effective during an acute attack.
1. Gastric ulceration 2. Bleeding 3. Hyperventilation 4. Reye's syndrome 5. Tinnitus (CN VIII)
ACIDazolamide' causes acidosis
Verapamil - Diltiazem - Bepridil

20. Name five Antiarrhythmic drugs in class II?
Paranteral (IV - SC)
propanolol - esmolol - metoprolol - atenolol - timolol
Norepinephrine
Liver

21. What microorganisms are Aminoglycosides ineffective against?
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine
Megaloblastic anemia - Leukopenia - Granulocytopenia
Antileukotriene; blocks leukotriene receptors.
Anaerobes

22. What is the possible mechanism and effect of Metformin in treating diabetes?
Reserpine inhibits dopamine transport into vesicles - attenuating its conversion to NE by dopamine beta - hydroxylase.
Malaria (P. falciparum)
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels
Phase 1 = prolonged depolarization - no antidote - effect potentiated by anticholinesterase; Phase 2 = repolarized but blocked - an anticholinesterase is the antidote for this phase.

23. What is an acronym to remember Anti - TB drugs?
Competitive inibitor of progestins at progesterone receptors.
RESPIre
- Cloazapine - carbamazapine - colchicine - PTU
Pentavalent Antimony

24. List the mechanism - clinical use - & toxicity of Etoposide.
Nonspecific beta - agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Adverse effect is tachycardia (Beta 1).
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.
Hydralazine and Minoxidil

25. What is the enzyme inhibited - the effect of this inhibition - and the clinical use of the antiandrogren Finasteride?
Heparin catalyzes the activation of antithrombin III.
Finasteride inhibits 5 Alpha - reductase - this decreases the conversion of testosterone to dihydrotestosterone - useful in BPH
Ceftriaxone
Useful in muscle paralysis during surgery or mechanical ventilation.

26. What is the MOA of Aztreonam?
Well tolerated in general but occasionally - Nephrotoxicity - Ototoxicity - Thrombophlebitis - diffuse flushing='Red Man Syndrome'
- Hypersensitivity reactions - Hemolysis - Nephrotoxicity (tubulointerstitial nephritis) - Kernicterus in infants Displace other drugs from albumin (e.g. - warfarin)
Tetracycline - Doxycycline - Demeclocycline - Minocycline
Inhibits cell wall synthesis ( binds to PBP3). A monobactam

27. Which drug(s) cause this reaction: Anaphylaxis?
The PT.
Methylation of rRNA near Erythromycin's ribosome binding site
- Penicillin
sedation - sleep alterations

28. Preferential action of the Ca2+ channel blockers at cardiac muscle?
Sucralfate cannot work in the presence of antacids or H2 blockers because it requires an acidic environment to polymerize.
cardiac muscle: Verapamil>Diltiazem>Nifedipine
Digitoxin>95% Digoxin 75%
Increases mean - systolic - and diastolic bp - while there is little change in pulse pressure.

29. Triamterene and amiloride - mechanism?
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.
Rash - Pseudomembranous colitis
block Na+ channels in the cortical collecting tubule
1. Hypoglycemia (more common with 2nd - generation drugs: glyburide - glipizide) 2. Disulfiram - like effects (not seen with 2nd - generation drugs).

30. Antimicrobial prophylaxis for PCP
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).
Nitrates
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.
TMP- SMZ (DOC) - aerosolized pentamidine

31. What is the mechanism of action of Warfarin (Coumadin)?
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids
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.
-100% oxygen - hyperbaric
Vd= (Amt. of drug in body/ Plasma drug conc.)

32. What is the MOA for Trimethoprim (TMP)?
check PFTs - LFTs - and TFTs
In treatment of malignant hyperthermia - due to concomitant use of halothane and succinylcholine. Also in neuroleptic malignant syndrome - a toxicity of antipsychotic drugs.
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow
Inhibits bacterial Dihydrofolate Reductase - Bacteriostatic

33. ________ ae not resistant to penicillinase - - but they are less susceptible than the other Beta lactams
Digitoxin 168hrs Digoxin 40 hrs
Cephalosporins
Vd= (Amt. of drug in body/ Plasma drug conc.)
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.

34. Which drug(s) cause this reaction: Neuro and Nephrotoxic?
for RSV
- polymyxins
- Haloperidol - chlorpromazine - reserpine - MPTP
Minor hepatotoxicity - Drug interactions (activates P450)

35. What is the mechanism of Tacrolimus (FK506)?
Inhibits formation of Initiation Complex - causes misreading of mRNA - Bactericidal
Similar to cyclosporine; binds to FK- binding protein - inhibiting secretion of IL-2 and other cytokines.
Prevention of NSAID- induced peptic ulcers - maintains a PDA.
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased

36. What are four unwanted effects of Clomiphene use?
Pituitary hormone.
1. Hot flashes 2. Ovarian enlargement 3. Multiple simultaneous pregnancies 4. Visual disturbances
Methylzanthine; desired effect is bronchodilation - may cause bronchodilation by inhibiting phosphodiesterase - enzyme involved in degrading cAMP (controversial).
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity

37. List the mechanism - clinical use - & toxicity of Methotrexate.
ACE inhibitor.
- Fluoroquinolones
- Corticosteroids - heparin
- S- phase anti - metabolite folate analogue - Luk - Lymp - sarc - RA - & psoriasis / - Reversible myelosuppression

38. Why is there a drop in systolic - mean - and diastolic bp with infusion of isoproterenol?
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
Stimulates beta adrenergic receptors
cholestyramine - colestipol
Overdose produces hepatic necrosis; acetaminophen metablolite depletes glutathione and forms toxic tissue adducts in liver.

39. Acetazolamide - site of action?
Ibuprofen - Naproxen - and Indomethacin
proximal convoluted tubule
No - it inhibits the release of Nor Epi
fetal renal toxicity - hyperkalemia

40. Mg+- clinical use?
Oral
sedation - depression - nasal stuffiness - diarrhea
effective in torsade de pointes and digoxin toxicity
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.

41. Antimicrobial prophylaxis for Gonorrhea
Ceftriaxone
- EDTA - dimercaprol - succimer - & penicillamine
G6PD deficient individuals
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.

42. Which drug(s) cause this reaction: Drug induced Parkinson's (4) ?
GI upset
- Hydralazine - Procainamide - INH - phenytoin
Pituitary hormone.
- Haloperidol - chlorpromazine - reserpine - MPTP

43. What are the clinical uses for 3rd Generation Cephalosporins?
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)
Hypersensitivity reactions
Imipenem
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone

44. Which diuretics increase urine K+?
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
Nevirapine - Delavirdine
all except the K+ sparing diuretics Spironolactone - Triamterene - Amiloride
Chronic gout.

45. List five common glucocorticoids.
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone
Inhibit steroid synthesis - used in the treatment of polycystic ovarian syndrome to prevent hirsutism.
Digitoxin 70% Digoxin 20-40%
GI distress - Skin rash - and Seizures at high plasma levels

46. What is a prerequisite for Acyclovir activation?
Large anionic polymer - acidic
It must be Phosphorylated by Viral Thymidine Kinase
Quinolones
Lovastatin - Pravastatin - Simvastatin - Atorvastatin

47. Furosemide - class and mechanism?
Primaquine
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.
Yes

48. Do Tetracyclines penetrate the CNS?
Only in limited amounts
Malaria (P. falciparum)
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents
Bactericidal for: Gram + rod and cocci - Gram - cocci - and Spirochetes

49. What is the MOA of Polymyxins?
Buy AT 30 - CELL at 50'
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents
Bismuth and Amoxicillin or Tetracycline; against Helobacter pylori
Misoprostol is a PGE1 analog that increases the production and secretion of the gastic mucous barrier.

50. What are Aminoglycosides synergistic with?
Blocks viral penetration/uncoating; may act to buffer the pH of the endosome
Beta - lactam antibiotics
Finasteride inhibits 5 Alpha - reductase - this decreases the conversion of testosterone to dihydrotestosterone - useful in BPH
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.