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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. How is Trimethoprim used clinically?
Prophylaxis for Influenza A - Rubella; Parkinson's disease
fetal renal toxicity - hyperkalemia
Used in combination therapy with SMZ to sequentially block folate synthesis
Oral treatment of superficial infections

2. List the specific antidote for this toxin: Methanol & Ethylene glycol
GI side effects. (Indomethacin is less toxic - more commonly used.)
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.
Inhibits reabsorption of uric acid.
- Ethanol - dialysis - & fomepizole

3. A 12yo patient was treated for a reaction to a bee sting - What drug provides the best coverage of sympathomimetic receptors?
Epinephirine(Alpha1 -2 and Beta 1 -2)
Impairs the synthesis of vitamin K- dependent clotting factors
blocking the beta adrenergic receptor leads to decreased cAMP - and decreased Ca2+ flux
- Tetracycline - amiodarone - sulfonamides

4. ACE inhibitors - clinical use?
hypertension - CHF - diabetic renal disease
Pyridoxine (B6) administration
1. Bleeding 2. Teratogenicity 3. Drug - drug interactions
anticholinesterase glaucoma

5. Which antimicrobials inhibit protein synthesis at the 50S subunit? (4)
Inhibits CMV DNA polymerase
Misoprostol is contraindicated in women of childbearing potential because it is an abortifacient.
1) Chloramphenical = bacteriostatic 2) Erythromycin = bacteriostatic 3) Lincomycin = bacteriostatic 4)cLindamycin = bacteriostatic
Inhibit DNA Gyrase (topoisomerase II) - Bactericidal

6. What are signs of Sildenafil (Viagra) toxicity?
Enterobacter
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions
Antibiotic - protein synthesis inhibitor.
Headache - flushing - dyspepsia - blue - green color vision.

7. What microorganisms is Aztreonam not effective against?
Sotalol - Ibutilide - Bretylium - Amiodarone
Gram + and Anerobes
GI side effects. (Indomethacin is less toxic - more commonly used.)
fetal renal toxicity - hyperkalemia

8. Which drug(s) cause this reaction: Oto and Nephrotoxicity (3)?
Tricyclic antidepressant.
Early myocardial infarction.
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.
- aminoglycosides - loop diuretics - cisplatin

9. What is the mechanism of action of the Alpha - glucosidase inhibitors?
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
NO
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.
Flutamide is a nonsteroidal competitive inhibitor of androgens at the testosterone receptor - used in prostate carcinoma.

10. What are four advantages of newer low - molecular - weight heparins (Enoxaparin)?
1. Better bioavailability 2. 2 to 4 times longer half life 3. Can be administered subcutaneously 4. Does not require laboratory monitoring
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity
DOC in diagnosing and abolishing AV nodal arrhythmias
Beta - lactam antibiotics

11. Ethacrynic Acid - clinical use?
sedation - sleep alterations
Diuresis in pateints with sulfa allergy
Selectively inhibit cyclooxygenase (COX) isoform 2 - Which is found in inflammatory cells nad mediates inflammation and pain; spares COX-1 Which helps maintain the gastric mucosa.
Pentamidine

12. What microorganisms are clinical indications for Tetracycline therapy?

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13. For Warfarin What is the Duration of action
Na/K ATPase
Chronic (weeks or months)
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis

14. How is Leishmaniasis treated?
Praziquantel
Vibrio cholerae Acne Chlamydia Ureaplasma Urealyticum Mycoplasma pneumoniae Borrelia burgdorferi (Lyme's) Rickettsia Tularemia
- Hydralazine - Procainamide - INH - phenytoin
Pentavalent Antimony

15. List the specific antidote for this toxin: Copper
- partial agonist can have increased - decreased - /A21or equal potency as full agonist. - Potency is an independent factor.
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine
- Penicillamine
Acetylcholinesterase; ACh is broken down into choline and acetate.

16. What is the mechanism of action of Ticlopidine - Clopidogrel
viral kinase
Inhibits cGMP phosphodiesterase - casuing increased cGMP - smooth muscle relaxation in the corpus cavernosum - increased blood flow - and penile erection.
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.

17. Mg+- clinical use?
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.
- Daunorubicin & Doxorubicin
- Fluoroquinolones
effective in torsade de pointes and digoxin toxicity

18. Reserpine will block the syntheis of this drug and but not its precursor.
GI upset - Superinfections - Skin rashes - Headache - Dizziness
Digitoxin 70% Digoxin 20-40%
The PT.
Blocks Norepi - but not Dopamine

19. What are Aminoglycosides used for clinically?
Tendonitis and Tendon rupture
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.
Severe Gram - rod infections.
- Class III antiarrhythmics (sotalol) - class IA (quinidine)

20. Antiarrhythmic class IV- effects?
Immediate anticoagulation for PE - stroke - angina - MI - DVT.
Polymyxins
decrease conduction velocity - increase ERP - increase PR interval
- Antipsychotics

21. List the mechanism - clinical use - & toxicity of Paclitaxel.
Inhibit DNA Gyrase (topoisomerase II) - Bactericidal
Prophylaxis for Influenza A - Rubella; Parkinson's disease
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.
Erectile dysfunction.

22. What is the mechanism of action of Warfarin (Coumadin)?
TMP- SMZ
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens
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.
Well tolerated in general but occasionally - Nephrotoxicity - Ototoxicity - Thrombophlebitis - diffuse flushing='Red Man Syndrome'

23. What is the category of drug names ending in - tropin (e.g. Somatotropin)
- Alkalates DNA - CML - Pulmonary fibrosis hyperpigmentation
Pituitary hormone.
Used in combination therapy with SMZ to sequentially block folate synthesis
Ipratropium

24. What drug is used to treat Trematode/fluke (e.g. - Schistosomes - Paragonimus - Clonorchis) or Cysticercosis
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.
Praziquantel
Ipratropium
Hypersensitivity reactions

25. How does Ganciclovir's toxicity relate to that of Acyclovir?
Ganciclovir is more toxic to host enzymes
Fast vs. Slow Acetylators
Choline acetyltransferase
Ibuprofen - Naproxen - and Indomethacin

26. What organism is Imipenem/cilastatin the Drug of Choice for?
Enterobacter
proximal convoluted tubule - thin descending limb - and collecting duct
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.
Peptic ulcer disease.

27. What are the four conditions in Which Omeprazole - Lansoprazole is used?
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome
Ototoxicity - Hypokalemia - Dehydration - Allergy (sulfa) - Nephritis (interstitial) - Gout
DOC in diagnosing and abolishing AV nodal arrhythmias
No

28. Name two LPL stimulators.
vasodilator - increases cGMP to induce smooth muscle relaxation (arterioles>veins; afterload reduction)
Gemfibrozil - Clofibrate
- A57Blue lines in gingiva & long bones - Encephalopathy & Foot drop - Abdominal colic / - Sideroblastic anemia
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol

29. Name two bile acid resins.
Prefers beta's at low doses - but at higher doses alpha agonist effects are predominantly seen.
vascular sm. Mus.: Nifedipine>Diltiazem>Verapamil
cholestyramine - colestipol
proximal convoluted tubule

30. Acetazolamide causes?

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31. Why would a patient with cog - wheel rigidity and a shuffling gait be given benztropine?
Chronic (weeks or months)
Parkinson patients benefit from antimuscarinic agents through its inhibitory action within the indirect pathway.
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow
Cephalosporins

32. For Heparin What is the Structure
Beta1 more than B2
1. Weight gain 2. Hepatotoxicity (troglitazone)
Inhibit RT of HIV and prevent the incorporation of viral genome into the host DNA
Large anionic polymer - acidic

33. What side effect of using atropine to induce pupillary dilation would you expect?
Ipratropium
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.
Atropine would also block the receptors in the ciliary muscle - causing an impairment in accommodation (cycloplegia).
-100% oxygen - hyperbaric

34. In What population does Gray Baby Syndrome occur? Why?
Acute (hours)
Premature infants - because they lack UDP- glucuronyl transferase
Inhalational general anesthetic.
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.

35. Side effects of Isoniazid (INH)?
- Quinidine - quinine
Well tolerated in general but occasionally - Nephrotoxicity - Ototoxicity - Thrombophlebitis - diffuse flushing='Red Man Syndrome'
Beta -2 agonist.
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome

36. Which drug(s) cause this reaction: Gynecomastia (6)?
Inhalational general anesthetic.
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens
Ataxia - Dizziness - Slurred speech
- S- phase anti - metabolite folate analogue - Luk - Lymp - sarc - RA - & psoriasis / - Reversible myelosuppression

37. K+ sparing diuretics - site of action?
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).
cortical collecting tubule

38. What is Metronidazole used for clinically?
Immediate anticoagulation for PE - stroke - angina - MI - DVT.
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic
- B51Naloxone / naltrexone (Narcan)

39. What is Clindamycin used for clinically?
As an anticholinesterase it increases endogenous ACh and thus increases strength.
Tendonitis and Tendon rupture
Anaerobic infections (e.g. - B. fragilis - C. perfringens)
Misoprostol is a PGE1 analog that increases the production and secretion of the gastic mucous barrier.

40. Which drug(s) cause this reaction: Osteoporosis (2)?
- Corticosteroids - heparin
Gram + - Gram - - Norcardia - Chlamydia
Ibuprofen - Naproxen - and Indomethacin
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic

41. What is a possible toxicity of Alpha - glucosidase inhibitors used in type -2 diabetes?
Inhibits cell wall synthesis ( binds to PBP3). A monobactam
Because they require some residual islet function.
GI disturbances.
Chronic Hepatitis A and B - Kaposi's Sarcoma

42. How do spare receptors effect the Km?
- ED 50 is less than the Km (less than 50% of receptors)
sedation - positive Coombs' test
Inhibits CMV DNA polymerase
GI disturbances.

43. List the specific antidote for this toxin: TPA & Streptokinase
- Aminocaproic acid
Nevirapine - Delavirdine
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)

44. What are the clinical uses for Aztreonam?
Intrathecally
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
Gram - rods: Klebsiella species - Pseudomonas species - Serratia species

45. What are three possible complications of Heparin therapy?
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions
decrease conduction velocity - increase ERP - increase PR interval
Amphotericin B - Nystatin - Fluconazole/azoles

46. List the specific antidote for this toxin: Tricyclic antidepressants
Acts as a wide spectrum carbapenem
penicillinase resistant
- S- phase anti - metabolite Pyr analogue - Colon - solid tumors - & BCC/ - Irreversible myelosuppression
- NaHCO3

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

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48. Adverse effects of Clonidine?
GI upset - Superinfections - Skin rashes - Headache - Dizziness
1. RNA pol inhibitor 2. Revs up P450 3. Red/orange body fluids 4. Rapid resistance if used alone
- Ethosuxamide - sulfonamides - lamotrigine
dry mouth - sedation - severe rebound hypertension

49. What is the effect of the Glitazones in diabetes treatment?
- aminoglycosides - loop diuretics - cisplatin
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.
Lidocaine - Mexiletine - Tocainide
Increase target cell response to insulin.

50. What are three unwanted effects of Mifepristone?
Scopolamine
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain
carbonic anhydrase inhibitors - K+ sparing diuretics
Enterobacter