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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. Which drug(s) cause this reaction: P450 inhibition(6)?
- Cimetidine - ketoconazole - grapefruit juice - erythromycin - INH - sulfonamides
- Haloperidol - chlorpromazine - reserpine - MPTP
Hemicholinium inhibits the transport of choline into the nerve - thus inhibiting formation of ACh.
Used in combination therapy with SMZ to sequentially block folate synthesis

2. What is the lab value used to monitor the effectiveness of Warfarin therapy?
The PT.
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis
cyanide toxicity (releases CN)
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids

3. What do you treat Nematode/roundworm (pinworm - whipworm) infections with?
Yes
- Glucocorticoid withdrawal
1)Binds penicillin - binding proteins 2) Blocks transpeptidase cross - linking of cell wall 3) Activates autolytic enzymes
Mebendazole/Thiabendazole - Pyrantel Pamoate

4. In What population does Gray Baby Syndrome occur? Why?
Immediate anticoagulation for PE - stroke - angina - MI - DVT.
Premature infants - because they lack UDP- glucuronyl transferase
Enterobacter
Quinidine - Amiodarone - Procainamide - Disopyramide

5. What is the memory aid for subunit distribution of ribosomal inhibitors?

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6. Loop diuretics (furosemide)- site of action?
CMV Retinitis in IC pts When Ganciclovir fails
thick ascending limb
- Chloramphenicol - benzene - NSAIDS - PTU - phenytoin
Lidocaine - Mexiletine - Tocainide

7. What is action of insulin in the liver - in muscle - and in adipose tissue?
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.
Atropine would also block the receptors in the ciliary muscle - causing an impairment in accommodation (cycloplegia).
- Shifts the curve to the right - increases Km
Antileukotriene; blocks synthesis by lipoxygenase.

8. What is the MOA of Amantadine?
Same as penicillin. Extended spectrum antibiotics
Praziquantel
Interstitial nephritis
Blocks viral penetration/uncoating; may act to buffer the pH of the endosome

9. Which drug(s) cause this reaction: Extrapyramidal side effects (3)?
Parkinson patients benefit from antimuscarinic agents through its inhibitory action within the indirect pathway.
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.
Peptic ulcer disease.
- Chlorpromazine - thioridazine - haloperidol

10. What is the mechanism of action of the Alpha - glucosidase inhibitors?
Megaloblastic anemia - Leukopenia - Granulocytopenia
1. Gastric ulceration 2. Bleeding 3. Hyperventilation 4. Reye's syndrome 5. Tinnitus (CN VIII)
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.
Sucralfate cannot work in the presence of antacids or H2 blockers because it requires an acidic environment to polymerize.

11. What beta 2 agonist will help your 21yo Astma pt?
Inhibits Viral DNA polymerase
Albuterol - tertbutaline
Reversible block of histamine H2 receptors
Malaria (P. falciparum)

12. Which cancer drugs work at the level of mRNA(2)?
- Atropine & pralidoxime
- Steroids - Tamoxifen
Binds to the Pyrophosphate Binding Site of the enzyme
Methylation of rRNA near Erythromycin's ribosome binding site

13. What antimuscarinic agent is used in asthma and COPD?
GI distress - Tooth discoloration and Inhibition of bone growth in children - Fanconi's syndrome - Photosensitivity
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.
Ipratropium
Flecainide - Encainide - Propafenone

14. Resistance mechanisms for Vancomycin
Severe Gram - rod infections.
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity
physostigmine
1) Hypersensitivity reactions 2) Increased nephrotoxicity of Aminoglycosides 3) Disulfiram - like reaction with ethanol (those with a methylthiotetrazole group - e.g. - cefamandole)

15. Acetaldehyde is metabolized by Acetaldehyde dehydrogenase - Which drug inhibs this enzyme?
GI discomfort
HTN - CHF - calcium stone formation - nephrogenic DI.
atropine - homatropine - tropicamide
- Disulfram & also sulfonylureas - metronidazole

16. What can result due to antacid overuse?
Ciprofloxacin - Norfloxacin - Ofloxacin - Grepafloxacin - Enoxacin - Nalidixic acid
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.
Can affect absorption - bioavailability - or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying.
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.

17. Antiarrhythmic class IV- primary site of action?
1. Bleeding 2. Teratogenicity 3. Drug - drug interactions
Short.
Ototoxicity - Hypokalemia - Dehydration - Allergy (sulfa) - Nephritis (interstitial) - Gout
AV nodal cells

18. What is the category of drug names ending in - ane (e.g. Halothane)
bradycardia - AV block - CHF
Inhalational general anesthetic.
blocks SR Ca2+ channels
Gentamicin - Neomycin - Amikacin - Tobramycin - Streptomycin

19. What are two toxicities of the Glitazones?
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased
1. Weight gain 2. Hepatotoxicity (troglitazone)

20. Preferential action of the Ca2+ channel blockers at vascular smooth muscle?
Mg = Must go to the bathroom.
TMP- SMZ (DOC) - aerosolized pentamidine
vascular sm. Mus.: Nifedipine>Diltiazem>Verapamil
loop diuretics - spironolactone

21. For Heparin What is the Onset of action
Inhibit Ergosterol synthesis
Rapid (seconds)
Nephrotoxicity (esp. with Cephalosporins) - Ototoxicity (esp. with Loop Diuretics)
Dopamine; causes its release from intact nerve terminals

22. Why is carbachol and pilocarpine useful in treatment of glaucoma?
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).
cardiac depression - peripheral edema - flushing - dizziness - constipation
- Act on same receptor - Full has greater efficacy
Neutropenia (ticlopidine); reserved for those who cannot tolerate aspirin.

23. List the specific antidote for this toxin: Iron
- Deferoxamine
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow
- Corticosteroids - heparin
Babiturate.

24. What is the mecanism of action of Sucralfate?
Penicillin.
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.
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.
Dermatophytes (tinea - ringworm)

25. A fellow passenger on a Carnival cruise ship looks pale and diaphoretic - What antimuscarinic agent would you give them?
scopolamine
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
Ataxia - Dizziness - Slurred speech
Digitoxin>95% Digoxin 75%

26. Which antimicrobials inhibit protein synthesis at the 50S subunit? (4)
1) Chloramphenical = bacteriostatic 2) Erythromycin = bacteriostatic 3) Lincomycin = bacteriostatic 4)cLindamycin = bacteriostatic
Cryptococcal meningitis in AIDS patients and Candidal infections of all types
- Atropine & pralidoxime
Antibiotic - protein synthesis inhibitor.

27. What is the MOA for Vancomycin?
It acts presynaptically to increase NE release.
reversible SLE- like syndrome
Inhibits cell wall mucopeptide formation - Bactericidal
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.

28. Acetazolamide causes?

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29. What is the mechanism of action of Cyclosporine?
Intrathecally
Gram + - Gram - - Norcardia - Chlamydia
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.
Due to the presence of a bulkier R group

30. How can the t1/2 of INH be altered?
Inhibits reabsorption of uric acid.
Phosphorylation by a Viral Kinase
Succinylcholine
Fast vs. Slow Acetylators

31. What is the MOA for Carbenicillin - Piperacillin - and Ticarcillin?
No. Atropine is used to reduce urgency in mild cystitis. So it would aggravate the urinary retention.
- Normalize K+ - Lidocaine - & Anti - dig Mab
Same as penicillin. Extended spectrum antibiotics
sedation - positive Coombs' test

32. What patients are at risk for life threatening hypotension When taking Sildenafil (Viagra)?
SLUD (salivation - Lacrimation - urination - Defecation)as well as airway secretion - GI motility - acid secretions
1. Addison's disease 2. Inflammation 3. Immune suppression 4. Asthma
Those patients who are taking nitrates.
Diarrhea - Urination - Miosis - Bronchospasm - Bradycardia - Excitation of skeletal muscle and CNS - Lacrimation - Sweating - and Salivation = DUMBBELS; also abdominal cramping

33. Which drug increases Sys BP w/o affecting Pulse Pressure
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis
Epinephrine
Ca2+ (Loops Lose calcium)
Muscarinic antagonist; competatively blocks muscarinic receptors - preventing bronchoconstriction.

34. Describe Phase II metabolism in liver(3)?
Gram + - Gram - - Norcardia - Chlamydia
Fever/Chills - Hypotension - Nephrotoxicity - Arrhythmias
- acetylation - glucuron. - & sulfation - Conjugation - Polar product
IV vitamin K and fresh frozen plasma

35. What is the receptor affinity and clinical use of isoproterenol?
It affects beta receptors equally and is used in AV heart block (rare).
Reserpine inhibits dopamine transport into vesicles - attenuating its conversion to NE by dopamine beta - hydroxylase.
Oral
- Airway - Breathing - Circulation - Dextrose (thiamine & narcan) - ABCD

36. Name some common Sulfonamides (4)
decrease
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine
- Cloazapine - carbamazapine - colchicine - PTU
- Protamine

37. Toxic side effects of the Azoles?
Rheumatoid and osteoarthritis.
Beta lactams - inhibit cell wall synthesis - Bactericidal
Hormone synthesis inhibition (Gynecomastia) - Liver dysfunction (Inhibits CYP450) - Fever - Chills
- Phenytoin

38. What are common side effects of Amphotericin B?
Used in combination therapy with SMZ to sequentially block folate synthesis
Fever/Chills - Hypotension - Nephrotoxicity - Arrhythmias
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)
Ibuprofen - Naproxen - and Indomethacin

39. MOA: Disrupt fungal cell membranes
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
Gram + and Anerobes
Prefers beta's at low doses - but at higher doses alpha agonist effects are predominantly seen.
Amphotericin B - Nystatin - Fluconazole/azoles

40. What is the clinical utility of clonidine?
scopolamine
Treatment of hypertension - especially with renal disease (lowers bp centrally - so flow is maintained to kidney).
Benzodiazepine.
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility

41. Beta Blockers - BP?
decrease
Premature infants - because they lack UDP- glucuronyl transferase
Aplastic anemia (dose independent) - Gray Baby Syndrome
atropine - homatropine - tropicamide

42. How does a noncompetitive antagonist effect an agonist?
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions
Due to the presence of a bulkier R group
Carbachol - pilocarpine - physostigmine - echothiophate
- Shifts the curve down - reduces Vmax

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

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44. What physiological effects was the Anes using Atropine to tx
SLUD (salivation - Lacrimation - urination - Defecation)as well as airway secretion - GI motility - acid secretions
Rifampin
- Alkalating agent - testicular - bladder - ovary -& lung - Nephrotoxicity & CN VIII damage.
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.

45. Ca2+ channel blockers - mechanism?
Modification via Acetylation - Adenylation - or Phosphorylation
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.

46. Antiarrhythmic class IA effects?
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.
Digitoxin 70% Digoxin 20-40%
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow
Edrophonium

47. What is the mechanism of action of Ticlopidine - Clopidogrel
Mg = Must go to the bathroom.
Norepinephrine
- aminoglycosides - loop diuretics - cisplatin
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.

48. Digoxin v. Digitoxin: protein binding?
Rare.
Digitoxin 70% Digoxin 20-40%
Acts as a wide spectrum carbapenem
1. RNA pol inhibitor 2. Revs up P450 3. Red/orange body fluids 4. Rapid resistance if used alone

49. What are five toxicities associated with Tacrolimus (FK506)?
atropine - homatropine - tropicamide
Lidocaine - Mexiletine - Tocainide
- Vinca alkaloids(inhibit MT) - Paclitaxel
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.

50. What drug is used to diagnose myasthenia gravis?
Binds Ergosterol - forms Membrane Pores that Disrupt Homeostatis
- Formaldehyde & formic acid - severe acidosis & retinal damage
edrophonium (extremely short acting anticholinesterase)
- ACE inhibitors (Losartan>no cough)