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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 parasites are treated with Pyrantel Pamoate (more specific)?
Cilastatin
atropine - homatropine - tropicamide
is resistant
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)

2. What is the mechanism of action of NSAIDs other than Aspirin?
- reduction - oxy - & hydrolysis - H2O sol. Polar product - P450
fetal renal toxicity - hyperkalemia
Aminoglycosides
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.

3. Adverse effect of Nitroprusside?
Pentavalent Antimony
cyanide toxicity (releases CN)
- Tetracycline - amiodarone - sulfonamides
GI discomfort

4. Which antimuscarinic agents are used in producing mydriasis and cycloplegia?
atropine - homatropine - tropicamide
Misoprostol is contraindicated in women of childbearing potential because it is an abortifacient.
Oxygen
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.

5. What is clinical use for Carbenicillin - Piperacillin - and Ticarcillin?
Non - Nucleosides
all except the K+ sparing diuretics Spironolactone - Triamterene - Amiloride
Pseudomonas species and Gram - rods
Inhibit RT of HIV and prevent the incorporation of viral genome into the host DNA

6. Ca2+ channel blockers - mechanism?
Yes
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility
Binds ergosterol - Disrupts fungal membranes
Rapid (seconds)

7. What antimuscarinic agent is used in asthma and COPD?
Malaria (P. falciparum)
1. Predisposes to viral infections and lymphoma 2. Nephrotoxic (preventable with mannitol diuresis)
Amphetamine and Ephedrine
Ipratropium

8. List the specific antidote for this toxin: Warfarin
- Vitamin K & fresh frozen plasma
ACIDazolamide' causes acidosis
Gram + and Anerobes
No - it inhibits the release of Nor Epi

9. What drug is given for Pneumocystis carinii prophylaxis?
Pentamidine
- acetylation - glucuron. - & sulfation - Conjugation - Polar product
blocks SR Ca2+ channels
- A57Blue lines in gingiva & long bones - Encephalopathy & Foot drop - Abdominal colic / - Sideroblastic anemia

10. How do we stop angina?
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time
Potent immunosuppressive used in organ transplant recipients.
Abortifacient.
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.

11. How does resistance to Vancomycin occur?
Oral
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
With an amino acid change of D- ala D- ala to D- ala D- lac
Diarrhea - Urination - Miosis - Bronchospasm - Bradycardia - Excitation of skeletal muscle and CNS - Lacrimation - Sweating - and Salivation = DUMBBELS; also abdominal cramping

12. What is the MOA for the Macrolides?
GI discomfort - Acute cholestatic hepatitis - Eosinophilia - Skin rashes
- B51Naloxone / naltrexone (Narcan)
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.

13. What are the indications for using amphetamine?

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14. Hydralazine - toxicity?
Methylzanthine; desired effect is bronchodilation - may cause bronchodilation by inhibiting phosphodiesterase - enzyme involved in degrading cAMP (controversial).
- Tricyclic antidepressants
compensatory tachycardia - fluid retention - lupus - like syndrome
- Oral Contraceptives

15. What is the clinical use for Nystatin?
cyanide toxicity (releases CN)
Wide spectrum of systemic mycoses: Cryptococcus - Blastomyces - Coccidioides - Aspergillus - Histoplasma - Candida - Mucor
Topical and Oral - for Oral Candidiasis (Thrush)
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)

16. Which drug(s) cause this reaction: P450 inhibition(6)?
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.
Antimetabolite derivative of 6- mercaptopurine that interferes with the metablolism and synthesis of nucleic acid.
- Cimetidine - ketoconazole - grapefruit juice - erythromycin - INH - sulfonamides
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity

17. Which individuals are predisposed to Sulfonamide - induced hemolysis?
G6PD deficient individuals
Protamine Sulfate is used for rapid reversal of heparinization (positively charged molecule that binds to negatively charged heparin).
Binds Ergosterol - forms Membrane Pores that Disrupt Homeostatis
1)Binds penicillin - binding proteins 2) Blocks transpeptidase cross - linking of cell wall 3) Activates autolytic enzymes

18. What is the effect of epinephrine infusion on bp and pulse pressure?
Digitoxin>95% Digoxin 75%
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis
Prevents release of mediators from mast cells. Effective only for the prophylaxis of asthma. Not effective during an acute attack.
Increased systolic and pulse pressure - decreased diastolic pressure - and little change in mean pressure.

19. What is the MOA of the RT Inhibitors?
Rare.
Inhibit RT of HIV and prevent the incorporation of viral genome into the host DNA
Inhalational general anesthetic.
Blood

20. What is an occasional side effect of Aztreonam?
Anaerobic infections (e.g. - B. fragilis - C. perfringens)
GI upset
Nevirapine - Delavirdine
Rash - Pseudomembranous colitis

21. What microorganisms are Aminoglycosides ineffective against?
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).
Anaerobes
Blocks Norepi - but not Dopamine
H2 antagonist

22. When is HIV therapy initiated?
When pts have Low CD4+ (< 500 cells/cubic mm) or a High Viral Load
Diarrhea - Urination - Miosis - Bronchospasm - Bradycardia - Excitation of skeletal muscle and CNS - Lacrimation - Sweating - and Salivation = DUMBBELS; also abdominal cramping
Rheumatoid and osteoarthritis.
Ataxia - Dizziness - Slurred speech

23. What is the mechanism of action of the Alpha - glucosidase inhibitors?
Acute gout.
Intrathecally
Yes - it does not cross the placenta.
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.

24. Ethacrynic Acid - mechanism?
not a sulfonamide - but action is the same as furosemide
Severe Gram - rod infections.
Zidovudine (AZT) - Didanosine (ddI) - Zalcitabine (ddC) - Stavudine (d4T) - Lamivudine (3TC)
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic

25. Toxicities associated with Acyclovir?
Clavulanic acid
Delirium - Tremor - Nephrotoxicity
- Dimercaprol - succimer
- Estrogen receptor antagonist - Breast CA - increased endometrial CA risk

26. What is the memory key for the action of Sildenafil (Viagra)?
Nitrates
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone
Acetaminophen has antipyretic and analgesic properties - but lacks anti - inflammatory properties.
Sildenafil fills the penis

27. What is Nifurtimox administered for?

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28. Beta Blockers - CNS toxicity?
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.
sedation - sleep alterations
Foscarnet = pyroFosphate analog
cardiac depression - peripheral edema - flushing - dizziness - constipation

29. For Heparin What is the Ability to inhibit coagulation in vitro
Useful in muscle paralysis during surgery or mechanical ventilation.
Prevents the release of Ca from SR of skeletal muscle
Yes
Zidovudine (AZT) - Didanosine (ddI) - Zalcitabine (ddC) - Stavudine (d4T) - Lamivudine (3TC)

30. MOA: Block peptidoglycan synthesis
Bacitracin - Vancomycin
Interstitial nephritis
Binds Ergosterol - forms Membrane Pores that Disrupt Homeostatis
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis

31. List the mechanism - clinical use - & toxicity of Nitrosureas.
- EDTA - dimercaprol - succimer - & penicillamine
- Alkalate DNA - Brain tumors - CNS toxicity
- Daunorubicin & Doxorubicin
Inhibits bacterial Dihydrofolate Reductase - Bacteriostatic

32. What process does Zafirlukast interfere with?
- DNA intercalator - Hodgkin's - myeloma - sarcoma - and solid tumors - Cardiotoxicity & alopecia
Diuresis in pateints with sulfa allergy
Succinylcholine
Leukotrienes increasing bronchial tone.

33. What additional side effects exist for Ampicillin?
Acts as a wide spectrum carbapenem
Rash - Pseudomembranous colitis
Giardiasis - Amoebic dysentery (E. histolytica) - Bacterial vaginitis (Gardnerella vaginalis) - Trichomonas
Hypersensitivity reactions

34. For Warfarin What is the Mechanism of action
Amphotericin B - Nystatin - Fluconazole/azoles
Impairs the synthesis of vitamin K- dependent clotting factors
1. RNA pol inhibitor 2. Revs up P450 3. Red/orange body fluids 4. Rapid resistance if used alone
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic

35. Name the common Non - Nucleoside Reverse Transcriptase Inhibitors
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.
Nevirapine - Delavirdine
Beta -2 agonist.
Quinidine - Amiodarone - Procainamide - Disopyramide

36. How does angiotensin II affect NE release?
It acts presynaptically to increase NE release.
Phenothiazine (neuroleptic - antiemetic).
- S- phase anti - metabolite Pyr analogue - Colon - solid tumors - & BCC/ - Irreversible myelosuppression
atropine - homatropine - tropicamide

37. Antiarrhythmic class IV- toxicity?
constipation - flushing - edema - CV effects (CHF - AV block - sinus node depression) - and torsade de pointes (Bepridil)
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.
torsade de pointes
Impairs the synthesis of vitamin K- dependent clotting factors

38. Name common Polymyxins
Prevents release of mediators from mast cells. Effective only for the prophylaxis of asthma. Not effective during an acute attack.
Pentavalent Antimony
Enterobacter
Polymyxin B - Polymyxin E

39. Are Ampicillin and Amoxicillin are not...
- Hydralazine - Procainamide - INH - phenytoin
penicillinase resistant
Succinylcholine
viral kinase

40. Mannitol - contraindications?
Chagas' disease - American Trypanosomiasis (Trypanosoma cruzi)
anuria - CHF
Cephalosporins
Triple sulfas or SMZ

41. What are Aminoglycosides used for clinically?
Severe Gram - rod infections.
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.
Hormone synthesis inhibition (Gynecomastia) - Liver dysfunction (Inhibits CYP450) - Fever - Chills
- Shifts the curve to the right - increases Km

42. ________ ae not resistant to penicillinase - - but they are less susceptible than the other Beta lactams
- Airway - Breathing - Circulation - Dextrose (thiamine & narcan) - ABCD
GI distress - Skin rash - and Seizures at high plasma levels
Rifampin (DOC) - minocycline
Cephalosporins

43. K+ sparing diuretics - clinical use?
Ibuprofen - Naproxen - and Indomethacin
VACUUM your Bed Room'
hyperaldosteronism - K+ depletion - CHF
PT

44. Why is there a drop in systolic - mean - and diastolic bp with infusion of isoproterenol?
Indomethacin is used to close a patent ductus arteriosus.
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
Spironolactone - Triamterene - Amiloride (the K+ STAys)
Activates cholinergic receptors on bladder and bowel smooth muscle - alleviating post - op and neurogenic ileus and urinary retention.

45. What is Metronidazole combined with for 'triple therapy'? Against What organism?
Butyrophenone (neuroleptic).
GET on the Metro
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs
Bismuth and Amoxicillin or Tetracycline; against Helobacter pylori

46. Adverse effects of Prazosin?
first dose orthostatic hypotension - dizziness - headache
Nifedipine - Verapamil - Diltiazem
Cryptococcal meningitis in AIDS patients and Candidal infections of all types
Prefers beta's at low doses - but at higher doses alpha agonist effects are predominantly seen.

47. Resistance mechanisms for Tetracycline
Pralidoxime regenerates active cholinesterase.
- Chlorpromazine - thioridazine - haloperidol
Chagas' disease - American Trypanosomiasis (Trypanosoma cruzi)
Decreased uptake or Increased transport out of cell

48. Explain differences between full and partial agonists(2).
proximal convoluted tubule - thin descending limb - and collecting duct
- Methylene blue
- Act on same receptor - Full has greater efficacy
Ipratropium

49. Would blockade of muscarininc receptors in the bladder be useful in treating urinary retention?
DOC in diagnosing and abolishing AV nodal arrhythmias
No. Atropine is used to reduce urgency in mild cystitis. So it would aggravate the urinary retention.
- Penicillamine
Penicillin - G

50. Antiarrhythmic class IV- clinical use?
Nephrotoxicity (esp. with Cephalosporins) - Ototoxicity (esp. with Loop Diuretics)
torsade de pointes - excessive Beta block
No - warfarin - unlike heparin - can cross the placenta.
prevention of nodal arrhythmias (SVT)