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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. Amprotericin B ___________ the BBB
Does not cross
Hemicholinium inhibits the transport of choline into the nerve - thus inhibiting formation of ACh.
Ld= (CpxVd)/F Cp=plasma conc. F= Bioaval.
Muscarinic antagonist; competatively blocks muscarinic receptors - preventing bronchoconstriction.

2. Which drug(s) cause this reaction: Pseudomembranous colitis?
- Clindamycin
Neomycin
Irreversibly inhibits H+/K+ ATPase in stomach parietal cells.
Pentamidine

3. List the specific antidote for this toxin: Salicylates
As an anticholinesterase it increases endogenous ACh and thus increases strength.
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone
- Alkalinize urine & dialysis
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis

4. Which drug(s) cause this reaction: Thrombotic complications?
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more
- Oral Contraceptives
As an anticholinesterase it increases endogenous ACh and thus increases strength.
Systemic mycoses

5. Acetazolamide - mechanism?
Antileukotriene; blocks leukotriene receptors.
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.
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone

6. What is Metronidazole used for clinically?
These B-2 agonists cause respiratory smooth muscle to relax.
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium
Quinolones
Same as penicillin. Extended spectrum antibiotics

7. What is the mechanism of action of Probenacid used to treat chronic gout?
Inhibits reabsorption of uric acid.
hypertension - CHF - diabetic renal disease
Butyrophenone (neuroleptic).
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain

8. What enzyme is responsible for the degredation of Ach
viral kinase
- S- phase anti - metabolite folate analogue - Luk - Lymp - sarc - RA - & psoriasis / - Reversible myelosuppression
- Class III antiarrhythmics (sotalol) - class IA (quinidine)
Acetylcholine esterase

9. Which Tetracycline is used in patients with renal failure? / Why?
loop diuretics - thiazides
Doxycycline - because it is fecally eliminated
Forms toxic metabolites in the bacterial cell - Bactericidal
Hypersensitivity reactions

10. These drugs acts indirectly by releasing strored catecholamines in the presynaptic terminal
- aminoglycosides - loop diuretics - cisplatin
Amphetamine and Ephedrine
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.
- Ammonium Chloride

11. What is the memory key for the action of Sildenafil (Viagra)?
Sildenafil fills the penis
blocking the beta adrenergic receptor leads to decreased cAMP - and decreased Ca2+ flux
is resistant
Rifampin (DOC) - minocycline

12. List the specific antidote for this toxin: Heparin
Short.
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.
- Protamine
torsade de pointes

13. How do the Protease Inhibitors work?
Hemolytic anemia
Binds Ergosterol - forms Membrane Pores that Disrupt Homeostatis
Inhibt Assembly of new virus by Blocking Protease Enzyme
NO HYPERURICEMIA - NO SULFA AllERGY; same as furosemide otherwise

14. What are the Macrolides used for clinically?
Suramin
- Upper respiratory tract infections - pneumonias - STDs: Gram+ cocci (streptococcal infect in pts allergic to penicillin) - Mycoplasma - Legionella - Chlamydia - Neisseria
Protamine sulfate
Beta 2 agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Use during acute exacerbation.

15. Which drug(s) cause this reaction: Tubulointerstitial Nephritis (5)?
Long.
GI discomfort - Acute cholestatic hepatitis - Eosinophilia - Skin rashes
Meningitis (H. influenza - N. meningitidis - S. pneumoniae) - Conserative treatment due to toxicities
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)

16. What are the four conditions in Which Omeprazole - Lansoprazole is used?
Antibiotic - protein synthesis inhibitor.
Depolymerizes microtubules - impairing leukocyte chemotaxis and degranulation.
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome

17. Common toxicities associated with Griseofulvin?
HSV - VZV - EBV - Mucocutaneous and Genital Herpes Lesions - Prophylaxis in Immunocompromised pts
Teratogenic - Carcinogenic - Confusion - Headaches
Same as penicillin. Extended spectrum antibiotics
CMV - esp in Immunocompromised patients

18. What enzyme is responsible for the production of Ach from Acetyl CoA and Choline
Hemolytic anemia
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.
Choline acetyltransferase
Short.

19. Acetazolamide causes?

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20. What is combined with Ampicillin - Amoxicillin - Carbenicillin - Piperacillin - and Ticarcillin to enhance their spectrum?
Clavulanic acid
- Chloramphenicol
Ganciclovir is more toxic to host enzymes
amphetamine and ephedrine

21. Steady state concentration is reached in __ number of half - lifes
In 4 half - lifes= (94%) T1/2 = (0.7x Vd)/CL
Bactericidal for: Gram + rod and cocci - Gram - cocci - and Spirochetes
Saquinavir - Ritonavir - Indinavir - Nelfinavir
1. Acarbose 2. Miglitol

22. Decrease Digoxin dose in renal failure?
Inhibit viral DNA polymerase
YES
torsade de pointes
Succinylcholine

23. What microorganisms is Aztreonam not effective against?
- acetylation - glucuron. - & sulfation - Conjugation - Polar product
Penicillin - V
Small lipid - soluble molecule
Gram + and Anerobes

24. Antiarrhythmic class IB- clinical uses?
decrease
Blocks Norepi - but not Dopamine
Chronic gout.
post MI and digitalis induced arrhythmias

25. What is the enzyme inhibited - the effect of this inhibition - and the clinical use of the antiandrogren Finasteride?
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine
- Oxalic acid - Acidosis & nephrotoxicity
Finasteride inhibits 5 Alpha - reductase - this decreases the conversion of testosterone to dihydrotestosterone - useful in BPH
sedation - sleep alterations

26. What is the category of drug names ending in - azol (e.g. Ketoconazole)
Polymyxin B - Polymyxin E
- Act on same receptor - Full has greater efficacy
Epinephrine
Antifungal.

27. Antiarrhythmic class IB- effects?
decrease AP duration - affects ischemic or depolarized Purkinje and ventricular system
It acts presynaptically to increase NE release.
- Corticosteroids - heparin
- aminoglycosides - loop diuretics - cisplatin

28. What is the most common cause of Pt noncompliance with Macrolides?
It must be Phosphorylated by Viral Thymidine Kinase
DOC in diagnosing and abolishing AV nodal arrhythmias
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine
GI discomfort

29. Name common Polymyxins
Polymyxin B - Polymyxin E
Norepinephrine (Alpha1 -2 and beta 1)
orthostatic and exercise hypotension - sexual dysfunction - diarrhea
1)Binds penicillin - binding proteins 2) Blocks transpeptidase cross - linking of cell wall 3) Activates autolytic enzymes

30. What is the MOA for the Cephalosporins?
- reduction - oxy - & hydrolysis - H2O sol. Polar product - P450
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids
Pseudomonas species and Gram - rods
Beta lactams - inhibit cell wall synthesis - Bactericidal

31. What is the mechanism of action of Heparin?
1. Weight gain 2. Hepatotoxicity (troglitazone)
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis
BM suppression (neutropenia - anemia) - Peripheral neuropathy
Heparin catalyzes the activation of antithrombin III.

32. Antiarrhythmic class IA effects?
Rash - Pseudomembranous colitis
Buy AT 30 - CELL at 50'
- Tetracycline - amiodarone - sulfonamides
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.

33. Name some common Sulfonamides (4)
In 4 half - lifes= (94%) T1/2 = (0.7x Vd)/CL
decrease conduction velocity - increase ERP - increase PR interval
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow

34. Can Warfarin be used during pregnancy?
No - warfarin - unlike heparin - can cross the placenta.
proarrhythmic
1) Hypersensitivity reactions 2) Increased nephrotoxicity of Aminoglycosides 3) Disulfiram - like reaction with ethanol (those with a methylthiotetrazole group - e.g. - cefamandole)
Epinephirine(Alpha1 -2 and Beta 1 -2)

35. Foscarnet toxicity?
Edrophonium
Nephrotoxicity
1. Buffalo hump 2. Moon facies 3. Truncal obesity 4. Muscle wasting 5. Thin skin 6. Easy bruisability 7. Osteoporosis 8. Adrenocortical atrophy 9. Peptic ulcers
Inhibit RT of HIV and prevent the incorporation of viral genome into the host DNA

36. What is the category - method of use - and adverse effects of Salmeterol in Asthma treatment?
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.
It affects beta receptors equally and is used in AV heart block (rare).
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
Digitoxin 70% Digoxin 20-40%

37. What are the major toxic side effects of Imipenem/cilastatin?
- Airway - Breathing - Circulation - Dextrose (thiamine & narcan) - ABCD
GI distress - Skin rash - and Seizures at high plasma levels
1. Bleeding 2. Teratogenicity 3. Drug - drug interactions
BM suppression (neutropenia - anemia) - Peripheral neuropathy

38. What are the clinical indications for bethanechol?
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome
Activates cholinergic receptors on bladder and bowel smooth muscle - alleviating post - op and neurogenic ileus and urinary retention.
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.
INH: Injures Neurons and Hepatocytes

39. How is Chloramphenical used clinically?
Meningitis (H. influenza - N. meningitidis - S. pneumoniae) - Conserative treatment due to toxicities
proarrhythmic
Benzathine penicillin G
- Phase I (clinical tests) - Phase II - Phase III - PhaseIV (surveillance)

40. What type of gout is treated with Colchicine?
Acute gout.
toxic
Staphlococcus aureus and Clostridium difficile (pseudomembranous colitis)
Gemfibrozil - Clofibrate

41. What is the difference between the affinity for beta receptors between albuterol/terbutaline and dantroline?
thiazides - amiloride
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.
dizziness - flushing - constipation (verapamil) - nausea
1. Antipyretic 2. Analgesic 3. Anti - inflammatory 4. Antiplatelet drug.

42. Adverse effects of Loop Diuretics?
sedation - positive Coombs' test
Pentavalent Antimony
K+ wasting - metabolic alkalosis - hypotension - ototoxicity
Increased systolic and pulse pressure - decreased diastolic pressure - and little change in mean pressure.

43. 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.
- Act on same receptor - Full has greater efficacy
toxic
BM suppression (neutropenia - anemia) - Peripheral neuropathy

44. What is the clinical use for Sildenafil (Viagra)?
Activates antithrombin III
Erectile dysfunction.
The PT.
GI discomfort

45. What process does Zafirlukast interfere with?
Leukotrienes increasing bronchial tone.
Erectile dysfunction.
Quinidine - Amiodarone - Procainamide - Disopyramide
Lipoxygenase

46. What drug is used during the pregnancy of an HIV+ mother? - Why?
Due to the presence of a bulkier R group
Gentamicin - Neomycin - Amikacin - Tobramycin - Streptomycin
- Quinidine - quinine
AZT - to reduce risk of Fetal Transmission

47. What is the mechanism of action of Aspirin?
Rare.
Premature infants - because they lack UDP- glucuronyl transferase
- Antipsychotics
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.

48. What is the category of drug names ending in - navir (e.g. Saquinavir)
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine
- Shifts the curve down - reduces Vmax
- Ethosuxamide - sulfonamides - lamotrigine
Protease inhibitor.

49. List the specific antidote for this toxin: Opioids
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.
- B51Naloxone / naltrexone (Narcan)
Can affect absorption - bioavailability - or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying.
Paranteral (IV - SC)

50. What do Aminoglycosides require for uptake?
Oxygen
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.
Prevents the release of calcium from the sarcoplasmic reticulum of skeletal muscle.
Flecainide - Encainide - Propafenone