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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 are are the Sulfonylureas (general description) and What is their use?
hyperaldosteronism - K+ depletion - CHF
Binds Ergosterol - forms Membrane Pores that Disrupt Homeostatis
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
Staphlococcus aureus and Clostridium difficile (pseudomembranous colitis)

2. Describe the MOA of Interferons (INF)
TMP- SMZ (DOC) - aerosolized pentamidine
Abortifacient.
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis
Systemic mycoses

3. What neurotransmitter does Amantadine affect? How does it influence this NT?
Dopamine; causes its release from intact nerve terminals
Prevents the release of calcium from the sarcoplasmic reticulum of skeletal muscle.
Same as penicillin. Extended spectrum antibiotics
Inhibits cGMP phosphodiesterase - casuing increased cGMP - smooth muscle relaxation in the corpus cavernosum - increased blood flow - and penile erection.

4. Which individuals are predisposed to Sulfonamide - induced hemolysis?
Beta -2 agonist.
Bactericidal for: Gram + rod and cocci - Gram - cocci - and Spirochetes
G6PD deficient individuals
torsade de pointes

5. Which drug(s) cause this reaction: Stevens - Johnson syn. (3)?
AZT - to reduce risk of Fetal Transmission
bradycardia - AV block - CHF
- Ethosuxamide - sulfonamides - lamotrigine
toxic

6. What is the MOA of Foscarnet?
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.
Inhibits Viral DNA polymerase
- Quinidine - quinine

7. What are three complications of Warfarin usage?
Hypersensitivity reactions
Reversible block of histamine H2 receptors
Same as penicillin. Extended spectrum antibiotics
1. Bleeding 2. Teratogenicity 3. Drug - drug interactions

8. The MOA for Chloramphenicol is?
Prefers beta's at low doses - but at higher doses alpha agonist effects are predominantly seen.
Decreases synthesis of Mycolic Acid
Inhibition of 50S peptidyl transferase - Bacteriostatic
TCA

9. Procainamide - toxicity?
aPTT (intrinsic pathway)
reversible SLE- like syndrome
It inhibits release of NE.
Stimulates beta adrenergic receptors

10. What beta 2 agonist will help your 21yo Astma pt?
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.
Prevents the release of calcium from the sarcoplasmic reticulum of skeletal muscle.
Albuterol - tertbutaline
GI distress - Tooth discoloration and Inhibition of bone growth in children - Fanconi's syndrome - Photosensitivity

11. Adverse effects of Minoxidil?
hypertension - CHF - diabetic renal disease
No
hypertrichosis - pericardial effusion - reflex tachycardia - angina - salt retention
1. Antipyretic 2. Analgesic 3. Anti - inflammatory 4. Antiplatelet drug.

12. Clinical use of Isoniazid (INH)?
- Vinca alkaloids(inhibit MT) - Paclitaxel
- Ethosuxamide - sulfonamides - lamotrigine
Mycobacterium tuberculosis - the only agent used as solo prophylaxis against TB
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)

13. List the mechanism - clinical use - & toxicity of Prednisone.

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14. List the specific antidote for this toxin: Anticholinesterases (organophosphate.)
1. Bleeding 2. Teratogenicity 3. Drug - drug interactions
- Atropine & pralidoxime
- Alkalate DNA - Brain tumors - CNS toxicity
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.

15. What are the side effects of Rifampin?
Minor hepatotoxicity - Drug interactions (activates P450)
Increase target cell response to insulin.
Potent immunosuppressive used in organ transplant recipients.
Chronic Hepatitis A and B - Kaposi's Sarcoma

16. What are Aminoglycosides used for clinically?
Severe Gram - rod infections.
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels
fetal renal toxicity - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
impotence - asthma - CV effects (bradycardia - CHF - AV block) - CNS effects (sedation - sleep alterations)

17. Which drug(s) cause this reaction: Extrapyramidal side effects (3)?
GI discomfort
Prevents the release of ACh - Which results in muscle paralysis.
torsade de pointes - excessive Beta block
- Chlorpromazine - thioridazine - haloperidol

18. Which drug(s) cause this reaction: Hot flashes?
- Tamoxifen
Protamine Sulfate is used for rapid reversal of heparinization (positively charged molecule that binds to negatively charged heparin).
proarrhythmic
Indomethacin is used to close a patent ductus arteriosus.

19. What is the category - desired effect - and possible mechanism of Theophylline in treating Asthma?
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).
- Clindamycin
Mebendazole/Thiabendazole - Pyrantel Pamoate
Methylzanthine; desired effect is bronchodilation - may cause bronchodilation by inhibiting phosphodiesterase - enzyme involved in degrading cAMP (controversial).

20. List the mechanism - clinical use - & toxicity of Bleomycin.
Prevents release of mediators from mast cells. Effective only for the prophylaxis of asthma. Not effective during an acute attack.
- reduction - oxy - & hydrolysis - H2O sol. Polar product - P450
compensatory tachycardia - fluid retention - lupus - like syndrome
- DNA intercalator - testicular & lymphomas - Pulmonary fibrosis mild myelosuppression.

21. Why is there a drop in systolic - mean - and diastolic bp with infusion of isoproterenol?
Chronic gout.
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
Hydralazine and Minoxidil
Liver

22. For Warfarin What is the Treatment for overdose
IV vitamin K and fresh frozen plasma
1. Meningococcal carrier state 2. Chemoprophylaxis in contacts of children with H. influenzae type B
GI disturbances.
- Formaldehyde & formic acid - severe acidosis & retinal damage

23. What is combination TMP- SMZ used to treat?
No - warfarin - unlike heparin - can cross the placenta.
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia
Erectile dysfunction.
1. Skin rash 2. Agranulocytosis (rare) 3. Aplastic anemia

24. What is the mechanism of action of Clomiphene?
Penicillin - Ampicillin - Ticarcillin - Pipercillin - Imipenem - Aztreonam - Cephalosporins
Pregnant women - Children; because animal studies show Damage to Cartilage
Non - Nucleosides
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.

25. List the specific antidote for this toxin: Iron
Hypersensitivity reactions
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
- Deferoxamine

26. MOA of Succinylcholine
- Tetracycline
- Alkalate DNA - Brain tumors - CNS toxicity
Prevents the release of Ca from SR of skeletal muscle
Benzodiazepine.

27. List the specific antidote for this toxin: Acetaminophen
Beta adrenergic receptors and Ca2+ channels (stimulatory)
Beta - lactamase cleavage of Beta - lactam ring
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic
- N- acetylcystine

28. What is a common side effect of Colchicine used to treat acute gout - especially When given orally?
CMV Retinitis in IC pts When Ganciclovir fails
GI side effects. (Indomethacin is less toxic - more commonly used.)
Due to the presence of a bulkier R group
GI intolerance (nausea - diarrhea) - Hyperglycemia - Lipid abnormalities - Thrombocytopenia (Indinavir)

29. What is the difference in receptor affinity of epinephrine at low doses? High doses?

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30. Mannitol - contraindications?
anuria - CHF
AZT - to reduce risk of Fetal Transmission
proarrhythmic
Activates antithrombin III

31. Which drug increases Sys BP w/o affecting Pulse Pressure
1. Renal damage 2. Aplastic anemia 3. GI distress
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.
Epinephrine
Polymyxin B - Polymyxin E

32. Which H2 Blocker has the most toxic effects and What are they?
Minor hepatotoxicity - Drug interactions (activates P450)
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.
troponin - tropomyosin system
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.

33. Resistance mechanisms for Cephalosporins/Penicillins
Beta - lactamase cleavage of Beta - lactam ring
bradycardia - AV block - CHF
- inhibits HGPRT (pur. Syn.) - Luk - Lymph
Prevents the release of ACh - Which results in muscle paralysis.

34. Norepi feedbacks and inhibits the presynaptic receptor by What mechanism
Nitrates
Acute gout.
Binding to the presynaptic alpha 2 release modulating receptors
Headache - flushing - dyspepsia - blue - green color vision.

35. What are four H2 Blockers?
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic
No - it inhibits the release of Nor Epi
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine
for RSV

36. Toxicities associated with Acyclovir?
Delirium - Tremor - Nephrotoxicity
1. Taken daily 2. No protection against STDs 3. Raises triglycerides 4. Depression - weight gain - nausea - HTN 5. Hypercoagulable state
Protease inhibitor.
Neomycin

37. How are the HIV drugs used clinically?

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38. Secretion of What drug is inhibited by Probenacid used to treat chronic gout?
Antileukotriene; blocks leukotriene receptors.
- Triggers apoptosis - CLL - Hodgkin's in MOPP - Cushing - like syndrome
Post - op and neurogenic ileus and urinary retention - myasthenia gravis - and reversal of neuromuscular junction blockade (post - op) through anticholinesterase activity.
Penicillin.

39. What is the clinical use for Clomiphene?
Nonspecific beta - agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Adverse effect is tachycardia (Beta 1).
Zidovudine (AZT) - Didanosine (ddI) - Zalcitabine (ddC) - Stavudine (d4T) - Lamivudine (3TC)
No - hemicholinum block the uptake of Choline and thus Ach synthesis
Treatment of infertility.

40. List the mechanism - clinical use - & toxicity of Busulfan.
impotence - exacerbation of asthma - CV effects - CNS effects - may mask hypoclycemia
Enterobacter
- Alkalates DNA - CML - Pulmonary fibrosis hyperpigmentation
1. Antipyretic 2. Analgesic 3. Anti - inflammatory

41. What are Amantadine - associated side effects?
Ataxia - Dizziness - Slurred speech
Buy AT 30 - CELL at 50'
Digitoxin>95% Digoxin 75%
Interferes with microtubule function - disrupts mitosis - inhibits growth

42. What are the phases of succinylcholine neuromuscular blockade?
Phase 1 = prolonged depolarization - no antidote - effect potentiated by anticholinesterase; Phase 2 = repolarized but blocked - an anticholinesterase is the antidote for this phase.
Beta antagonist.
anticholinesterase glaucoma
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.

43. Aztreonam is not usually...
toxic
Lidocaine - Mexiletine - Tocainide
1. RNA pol inhibitor 2. Revs up P450 3. Red/orange body fluids 4. Rapid resistance if used alone
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.

44. What can result due to antacid overuse?
Penicillin - V
Nevirapine - Delavirdine
Can affect absorption - bioavailability - or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying.
AmOxicillin has greater Oral bioavailability

45. How is Leishmaniasis treated?
Protamine sulfate
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.
AZT - to reduce risk of Fetal Transmission
Pentavalent Antimony

46. Preferential action of the Ca2+ channel blockers at cardiac muscle?
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.
cardiac muscle: Verapamil>Diltiazem>Nifedipine
Inhibits bacterial Dihydrofolate Reductase - Bacteriostatic
- Oral Contraceptives

47. What is the mechanism of action of Ticlopidine - Clopidogrel
No - warfarin - unlike heparin - can cross the placenta.
Saquinavir - Ritonavir - Indinavir - Nelfinavir
hypertension - angina - arrhythmias
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.

48. Hydralazine - clinical use?
propanolol - esmolol - metoprolol - atenolol - timolol
Nevirapine - Delavirdine
severe hypertension - CHF
- Alkalating agent - testicular - bladder - ovary -& lung - Nephrotoxicity & CN VIII damage.

49. What is are two clinical uses of Cyclosporine?
Binds ergosterol - Disrupts fungal membranes
hyperaldosteronism - K+ depletion - CHF
Carbenicillin - Piperacillin - and Ticarcillin
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.

50. What do Aminoglycosides require for uptake?
Bactericidal for: Gram + rod and cocci - Gram - cocci - and Spirochetes
Oxygen
Inhibits cell wall mucopeptide formation - Bactericidal
Hypersensitivity reactions