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USMLE Step 1 Pharmacology

Subjects : health-sciences, usmle-step-1

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Answer 50 questions in 15 minutes.
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Match each statement with the correct term.
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1. List the specific antidote for this toxin: Iron
Post - op and neurogenic ileus and urinary retention - myasthenia gravis - and reversal of neuromuscular junction blockade (post - op) through anticholinesterase activity.
Benzathine penicillin G
Severe Gram - rod infections.
- Deferoxamine

2. Ca2+ channel blockers - site of action?
Cell membrane Ca2+ channels of cardiac sarcomere
1. Antiandrogen 2. Nausea 3. Vomiting
Epinephrine
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)

3. Which drug(s) cause this reaction: Osteoporosis (2)?
- Corticosteroids - heparin
Carbenicillin - Piperacillin - and Ticarcillin
GI upset - Superinfections - Skin rashes - Headache - Dizziness
SLUD (salivation - Lacrimation - urination - Defecation)as well as airway secretion - GI motility - acid secretions

4. List the mechanism - clinical use - & toxicity of Cyclophosphamide.
Increases mean - systolic - and diastolic bp - while there is little change in pulse pressure.
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.
- Halothane - Valproic acid - acetaminophen - Amantia phalloides
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased

5. What anticholinesterase crosses the blood - brain - barrier?
ACIDazolamide' causes acidosis
physostigmine
Doxycycline - because it is fecally eliminated
Edrophonium

6. List the specific antidote for this toxin: Lead
Vibrio cholerae Acne Chlamydia Ureaplasma Urealyticum Mycoplasma pneumoniae Borrelia burgdorferi (Lyme's) Rickettsia Tularemia
- EDTA - dimercaprol - succimer - & penicillamine
Diarrhea
Slow - limited by half lives of clotting factors

7. What are the clinical uses for Aztreonam?
Atropine pts are suffering from Cholinestrase inhibitor poisining (Nerve gas/Organophosphate poisining)
Gram - rods: Klebsiella species - Pseudomonas species - Serratia species
Inhibt Assembly of new virus by Blocking Protease Enzyme
Prefers beta's at low doses - but at higher doses alpha agonist effects are predominantly seen.

8. Clonidine is the preferred sym pathomimetic tx of HTN in pts with renal disease - why??
- Niacin - Ca++ channel blockers - adenosine - vancomycin
Fluconazole - Ketoconazole - Clotrimazole - Miconazole - Itraconazole
Forms toxic metabolites in the bacterial cell - Bactericidal
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow

9. What are Aminoglycosides used for clinically?
Praziquantel
Severe Gram - rod infections.
Post - op and neurogenic ileus and urinary retention - myasthenia gravis - and reversal of neuromuscular junction blockade (post - op) through anticholinesterase activity.
1) Chloramphenical = bacteriostatic 2) Erythromycin = bacteriostatic 3) Lincomycin = bacteriostatic 4)cLindamycin = bacteriostatic

10. What is the MOA of Polymyxins?
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents
blocks SR Ca2+ channels
Na/K ATPase
Prevents the release of calcium from the sarcoplasmic reticulum of skeletal muscle.

11. What are the products and their toxicities of the metabolism of Methanol by / alcohol dehydrogenase?
Inhalational general anesthetic.
- acetylation - glucuron. - & sulfation - Conjugation - Polar product
Zidovudine (AZT) - Didanosine (ddI) - Zalcitabine (ddC) - Stavudine (d4T) - Lamivudine (3TC)
- Formaldehyde & formic acid - severe acidosis & retinal damage

12. What is the category of drug names ending in - barbital (e.g. Phenobarbital)
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
Babiturate.
- Triggers apoptosis - CLL - Hodgkin's in MOPP - Cushing - like syndrome
Cryptococcal meningitis in AIDS patients and Candidal infections of all types

13. What are Polymyxins used for?
Give an antichloinesterase - neostigmine - edrophonium - etc
edrophonium (extremely short acting anticholinesterase)
Beta - lactam antibiotics
Resistant Gram - infections

14. What are Amantadine - associated side effects?
Inhibit RT of HIV and prevent the incorporation of viral genome into the host DNA
Ataxia - Dizziness - Slurred speech
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions
Give an antichloinesterase - neostigmine - edrophonium - etc

15. What is the memory key for organisms treated with Tetracyclines?

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16. List the specific antidote for this toxin: Methanol & Ethylene glycol
Verapamil - Diltiazem - Bepridil
- Phenytoin
Antileukotriene; blocks synthesis by lipoxygenase.
- Ethanol - dialysis - & fomepizole

17. What is Ketoconazole specifically used for?
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine
Epinephirine(Alpha1 -2 and Beta 1 -2)
Blastomyces - Coccidioides - Histoplasma - C. albicans; Hypercortisolism
- Isoniazid

18. How is Amantadine used clinically?

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19. Why is pyridostigmine effective in the treatment of myasthenia gravis?
toxic
As an anticholinesterase it increases endogenous ACh and thus increases strength.
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.
Protamine Sulfate is used for rapid reversal of heparinization (positively charged molecule that binds to negatively charged heparin).

20. MOA: Block protein synthesis at 30s subunit
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis
Aminoglycosides - Tetracyclines
local anesthetic. CNS stimulation or depression. CV depression.
Fluconazole - Ketoconazole - Clotrimazole - Miconazole - Itraconazole

21. What is the clinical use for Sildenafil (Viagra)?
Tubocurarine - atracurium - mivacurium - pancuronium - vecuronium - rapacuronium
GI discomfort
Erectile dysfunction.
Inhibits cell wall synthesis ( binds to PBP3). A monobactam

22. How is Trimethoprim used clinically?
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis
Used in combination therapy with SMZ to sequentially block folate synthesis
proximal convoluted tubule
Ld= (CpxVd)/F Cp=plasma conc. F= Bioaval.

23. K+ sparing diuretics - toxicity?
Activates cholinergic receptors on bladder and bowel smooth muscle - alleviating post - op and neurogenic ileus and urinary retention.
Anaerobes
hyperkalemia - endocrine effects (gynecomastia - anti - androgen)
Constant FRACTION eliminated per unit time.(exponential)

24. What is the MOA for Amphotericin B?
Binds Ergosterol - forms Membrane Pores that Disrupt Homeostatis
thick ascending limb
Beta antagonist.
Pentamidine

25. Will Hemicholinum affect the release of stored Ach during Cholinergic Stimulation
Only in limited amounts
decrease
No - hemicholinum block the uptake of Choline and thus Ach synthesis
- Tamoxifen

26. How are the HIV drugs used clinically?

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27. What is the category of drug names ending in - cillin (e.g. Methicillin)
Nephrotoxicity
Rash - Pseudomembranous colitis
Inhibition of 50S peptidyl transferase - Bacteriostatic
Penicillin.

28. Which cancer drugs inhibit nucleotide synthesis(3)?
- Methotrexate - 5 FU - 6 mercaptopurine
Rifampin - Ethambutol - Streptomycin - Pyrazinamide - Isoniazid (INH)
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.
Carbenicillin - Piperacillin - and Ticarcillin

29. Procainamide - toxicity?
Succinylcholine
thick ascending limb
Dopamine; causes its release from intact nerve terminals
reversible SLE- like syndrome

30. What are common side effects of Amphotericin B?
Antifungal.
Fever/Chills - Hypotension - Nephrotoxicity - Arrhythmias
Epinephrine
- Formaldehyde & formic acid - severe acidosis & retinal damage

31. Antiarrhythmic class IB- toxicity?
Pentamidine
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.
local anesthetic. CNS stimulation or depression. CV depression.
Neutropenia

32. What is the clinical use for Nystatin?
Interstitial nephritis
Topical and Oral - for Oral Candidiasis (Thrush)
Beta antagonist.
- S- phase anti - metabolite Pyr analogue - Colon - solid tumors - & BCC/ - Irreversible myelosuppression

33. Nifedipine has similar action to?
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.
Nitrates
Ld= (CpxVd)/F Cp=plasma conc. F= Bioaval.
Inhibt Assembly of new virus by Blocking Protease Enzyme

34. For Heparin What is the Structure
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.
fetal renal toxicity - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
Large anionic polymer - acidic
Penicillin - G

35. Can Warfarin be used during pregnancy?
Extended spectrum penicillin: certain Gram + bacteria and Gram - rods
Hypersensitivity reactions
No - warfarin - unlike heparin - can cross the placenta.
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.

36. What is the mechanism of action of Mifepristone (RU486)?
Norepinephrine (Alpha1 -2 and beta 1)
Competitive inibitor of progestins at progesterone receptors.
- Estrogen receptor antagonist - Breast CA - increased endometrial CA risk
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide

37. What is the MOA for the Aminoglycosides?
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.
- Class III antiarrhythmics (sotalol) - class IA (quinidine)
Inhibits formation of Initiation Complex - causes misreading of mRNA - Bactericidal
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.

38. For Heparin What is the Route of administration
Paranteral (IV - SC)
Dermatophytes (tinea - ringworm)
orthostatic and exercise hypotension - sexual dysfunction - diarrhea
Nonspecific beta - agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Adverse effect is tachycardia (Beta 1).

39. What is the MOA of the RT Inhibitors?
Acetylcholine esterase
very short acting
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
Inhibit RT of HIV and prevent the incorporation of viral genome into the host DNA

40. What is the MOA of Amantadine?
Inhibt Assembly of new virus by Blocking Protease Enzyme
1. Predisposes to viral infections and lymphoma 2. Nephrotoxic (preventable with mannitol diuresis)
hyperaldosteronism - K+ depletion - CHF
Blocks viral penetration/uncoating; may act to buffer the pH of the endosome

41. Are not penicillinase resistant
Beta1 more than B2
Blocking muscarinic receptors in the circular fibers of the eye - results in unopposed action of radial muscles to dilate.
Carbenicillin - Piperacillin - and Ticarcillin
- Disulfram & also sulfonylureas - metronidazole

42. What is a common drug interaction associated with Griseofulvin?
torsade de pointes - excessive Beta block
Chronic gout.
Constant FRACTION eliminated per unit time.(exponential)
Increases coumadin metabolism

43. Which antimicrobial classes inhibit protein synthesis at the 30S subunit? (2)
torsade de pointes
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic
Imipenem
Antibiotic - protein synthesis inhibitor.

44. List the mechanism - clinical use - & toxicity of 5 FU.
- S- phase anti - metabolite folate analogue - Luk - Lymp - sarc - RA - & psoriasis / - Reversible myelosuppression
- S- phase anti - metabolite Pyr analogue - Colon - solid tumors - & BCC/ - Irreversible myelosuppression
- aminoglycosides - loop diuretics - cisplatin
Mg = Must go to the bathroom.

45. Name three calcium channel blockers?
Pralidoxime regenerates active cholinesterase.
cross - allergenic
1. Acarbose 2. Miglitol
Nifedipine - Verapamil - Diltiazem

46. How would you reverse the effect of a neuromuscular blocking agent?
Give an antichloinesterase - neostigmine - edrophonium - etc
Binds Ergosterol - forms Membrane Pores that Disrupt Homeostatis
Minor hepatotoxicity - Drug interactions (activates P450)
Pregnant women - Children; because animal studies show Damage to Cartilage

47. How can Isoniazid (INH)- induced neurotoxicity be prevented?
Lipoxygenase
Pyridoxine (B6) administration
vasodilator - increases cGMP to induce smooth muscle relaxation (arterioles>veins; afterload reduction)
is resistant

48. Where does Griseofulvin deposit?
Keratin containing tissues - e.g. - nails
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)
Neutropenia (ticlopidine); reserved for those who cannot tolerate aspirin.
Finasteride inhibits 5 Alpha - reductase - this decreases the conversion of testosterone to dihydrotestosterone - useful in BPH

49. What is a Ribavirin toxicity?
Hemolytic anemia
- Physostigmine salicylate
Rifampin - Ethambutol - Streptomycin - Pyrazinamide - Isoniazid (INH)
Bethanechol - Neostigmine - physostigmine

50. Why would dopamine be useful in treating shock?
- Alkalates DNA - CML - Pulmonary fibrosis hyperpigmentation
Receptors = D1=D2>beta>alpha - thus increasing heart rate (beta) and blood pressure (alpha vasoconstriction) while maintaining kidney perfusion (dopamine receptors)
They inhibit reuptake of NE at the nerve terminal (as does cocaine).
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.