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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. What is the category of drug names ending in - oxin (e.g. Digoxin)
not a sulfonamide - but action is the same as furosemide
Cardiac glycoside (inotropic agent).
Neurotoxicity - Acute renal tubular necrosis
AmOxicillin has greater Oral bioavailability

2. What is the possible mechanism and effect of Metformin in treating diabetes?
Premature infants - because they lack UDP- glucuronyl transferase
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs
CMV Retinitis in IC pts When Ganciclovir fails

3. What are four thrombolytics?
1. Streptokinase 2. Urokinase 3. tPA (alteplase) - APSAC (anistreplase)
Neostigmine - pyridostigmine edrophonium - physostigmine echothiophate
Flecainide - Encainide - Propafenone
Binding to the presynaptic alpha 2 release modulating receptors

4. Acetazolamide causes?

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5. How does Ganciclovir's toxicity relate to that of Acyclovir?
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens
Ganciclovir is more toxic to host enzymes
- Dimercaprol - succimer
Interstitial nephritis

6. Antiarrhythmic class II- mechanism?
Lidocaine - Mexiletine - Tocainide
blocking the beta adrenergic receptor leads to decreased cAMP - and decreased Ca2+ flux
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.

7. For Heparin What is the Onset of action
Rapid (seconds)
Cell membrane Ca2+ channels of cardiac sarcomere
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility
Yes

8. For Heparin What is the Site of action
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
Blood
Beta Blockers
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.

9. What is the mechanism of action of the thrombolytics?
amphetamine and ephedrine
Directly of indirectly aid conversion of plasminogen to plasmin Which cleaves thrombin and fibrin clots. (It is claimed that tPA specifically converts fibrin - bound plasminogen to plasmin.)
Immediate anticoagulation for PE - stroke - angina - MI - DVT.
Increase target cell response to insulin.

10. Ibutilide - toxicity?
torsade de pointes
K+ wasting - metabolic alkalosis - hypotension - ototoxicity
Fever/Chills - Hypotension - Nephrotoxicity - Arrhythmias
Prevention of NSAID- induced peptic ulcers - maintains a PDA.

11. Which drug(s) cause this reaction: Photosensitivity(3)?
- Tetracycline - amiodarone - sulfonamides
all except the K+ sparing diuretics Spironolactone - Triamterene - Amiloride
- Class III antiarrhythmics (sotalol) - class IA (quinidine)
IV vitamin K and fresh frozen plasma

12. For Warfarin What is the Site of action
Liver
Anaerobes
cardiac muscle: Verapamil>Diltiazem>Nifedipine
Albuterol - tertbutaline

13. What are the major toxic side effects of the Cephalosporins?
1) Hypersensitivity reactions 2) Increased nephrotoxicity of Aminoglycosides 3) Disulfiram - like reaction with ethanol (those with a methylthiotetrazole group - e.g. - cefamandole)
Chronic (weeks or months)
Wide spectrum of systemic mycoses: Cryptococcus - Blastomyces - Coccidioides - Aspergillus - Histoplasma - Candida - Mucor
No

14. Spironolactone - mechanism?
Corticosteroids; prevent production of leukotrienes from arachodonic acid by blocking phospholipase A2. Drugs of choice in a patient with status asthmaticus (in combination with albuterol.)
competitive inhibirot of aldosterone in the cortical collecting tubule
decrease AP duration - affects ischemic or depolarized Purkinje and ventricular system
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic

15. What is a possible result of overdose of Acetaminophen?
new arrhythmias - hypotension
Those patients who are taking nitrates.
Overdose produces hepatic necrosis; acetaminophen metablolite depletes glutathione and forms toxic tissue adducts in liver.
Yes

16. What are three clinical uses of the Leuprolide?
1. Antiandrogen 2. Nausea 3. Vomiting
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids
atropine - homatropine - tropicamide
Prevents release of mediators from mast cells. Effective only for the prophylaxis of asthma. Not effective during an acute attack.

17. What is the MOA for the Cephalosporins?
- Glucagon
No. Atropine is used to reduce urgency in mild cystitis. So it would aggravate the urinary retention.
Cardiac glycoside (inotropic agent).
Beta lactams - inhibit cell wall synthesis - Bactericidal

18. What are Aminoglycosides used for clinically?
thick ascending limb
HSV - VZV - EBV - Mucocutaneous and Genital Herpes Lesions - Prophylaxis in Immunocompromised pts
Binds to the Pyrophosphate Binding Site of the enzyme
Severe Gram - rod infections.

19. List the specific antidote for this toxin: Salicylates
Penicillin - G
- Alkalinize urine & dialysis
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic
Chronic gout.

20. How is Vancomycin used clinically?
Aplastic anemia (dose independent) - Gray Baby Syndrome
Aminoglycosides
Potent immunosuppressive used in organ transplant recipients.
For serious - Gram + multidrug - resistant organisms

21. Adverse effects of ganglionic blockers?
anticholinesterase glaucoma
severe orthostatic hypotension - blurred vision - constipation - sexual dysfunction
Suramin
Misoprostol is a PGE1 analog that increases the production and secretion of the gastic mucous barrier.

22. Ca2+ channel blockers - site of action?
thick ascending limb
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids
Cell membrane Ca2+ channels of cardiac sarcomere
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)

23. Hydrochlorothiazide - mechanism?
Inhibits DNA dependent RNA polymerase
Hexamethonium is a nicotinic antagonist - and thus is a ganglionic blocker.
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow

24. What is the clincial use for Misoprostol?
GI intolerance (nausea - diarrhea) - Hyperglycemia - Lipid abnormalities - Thrombocytopenia (Indinavir)
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.
Blastomyces - Coccidioides - Histoplasma - C. albicans; Hypercortisolism
Prevention of NSAID- induced peptic ulcers - maintains a PDA.

25. What is the clinical use for Sildenafil (Viagra)?
thick ascending limb
Erectile dysfunction.
Mycobacterium tuberculosis - the only agent used as solo prophylaxis against TB
Beta - lactam antibiotics

26. Why would a patient with cog - wheel rigidity and a shuffling gait be given benztropine?
- Isoniazid
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.
1)Binds penicillin - binding proteins 2) Blocks transpeptidase cross - linking of cell wall 3) Activates autolytic enzymes
Parkinson patients benefit from antimuscarinic agents through its inhibitory action within the indirect pathway.

27. How is Acyclovir used clinically?
HSV - VZV - EBV - Mucocutaneous and Genital Herpes Lesions - Prophylaxis in Immunocompromised pts
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia
Lipoxygenase

28. Can Heparin be used during pregnancy?
Prophylaxis for Influenza A - Rubella; Parkinson's disease
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
Yes - it does not cross the placenta.
Sucralfate cannot work in the presence of antacids or H2 blockers because it requires an acidic environment to polymerize.

29. What are the clinical uses for Imipenem/cilastatin?
cardiac depression - peripheral edema - flushing - dizziness - constipation
Gram + cocci - Gram - rods - and Anerobes
Chronic gout.
1. Acarbose 2. Miglitol

30. 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.
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.
dizziness - flushing - constipation (verapamil) - nausea
INH: Injures Neurons and Hepatocytes

31. Name five Antiarrhythmic drugs in class II?
propanolol - esmolol - metoprolol - atenolol - timolol
- EDTA - dimercaprol - succimer - & penicillamine
1. Bleeding 2. Teratogenicity 3. Drug - drug interactions
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.

32. Antiarrhythmic class IB- toxicity?
local anesthetic. CNS stimulation or depression. CV depression.
Systemic mycoses
Bethanechol - Neostigmine - physostigmine
Cell membrane Ca2+ channels of cardiac sarcomere

33. Adverse effects of Loop Diuretics?
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.
K+ wasting - metabolic alkalosis - hypotension - ototoxicity
Beta antagonist.
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.

34. What is the formula for Clearance (CL)
- Alkalates DNA - CML - Pulmonary fibrosis hyperpigmentation
Nitrates
Beta antagonist.
CL= (rate of elimination of drug/ Plasma drug conc.)

35. How is Trimethoprim used clinically?
- Alkalate DNA - Brain tumors - CNS toxicity
Used in combination therapy with SMZ to sequentially block folate synthesis
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.
vascular sm. Mus.: Nifedipine>Diltiazem>Verapamil

36. What is the MOA for Acyclovir?
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.
Inhibit viral DNA polymerase
Increases coumadin metabolism

37. How would hemicholinium treatment affect cholinergic neurons?
Hemicholinium inhibits the transport of choline into the nerve - thus inhibiting formation of ACh.
Prevents the release of calcium from the sarcoplasmic reticulum of skeletal muscle.
- Steroids - Tamoxifen
Prevents the release of ACh - Which results in muscle paralysis.

38. Which drug(s) cause this reaction: Osteoporosis (2)?
cyanide toxicity (releases CN)
- Methotrexate - 5 FU - 6 mercaptopurine
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
- Corticosteroids - heparin

39. Mannitol - site of action?
proximal convoluted tubule - thin descending limb - and collecting duct
Primaquine
- Daunorubicin & Doxorubicin
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.

40. What is the mechanism of action of Allopurinol used to treat chronic gout?
1. Hot flashes 2. Ovarian enlargement 3. Multiple simultaneous pregnancies 4. Visual disturbances
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.
Inhibits cell wall mucopeptide formation - Bactericidal
Choline acetyltransferase

41. What is the category of drug names ending in - pril (e.g. Captopril)
thiazides - amiloride
Depolymerizes microtubules - impairing leukocyte chemotaxis and degranulation.
Dermatophytes (tinea - ringworm)
ACE inhibitor.

42. Which drug(s) cause this reaction: P450 inhibition(6)?
Beta lactams - inhibit cell wall synthesis - Bactericidal
Pretreat with antihistamines and a slow infusion rate
- Cimetidine - ketoconazole - grapefruit juice - erythromycin - INH - sulfonamides
Beta Blockers

43. MOA: Disrupt fungal cell membranes
aPTT (intrinsic pathway)
Amphotericin B - Nystatin - Fluconazole/azoles
- Bleomycin - amiodarone - busulfan
These B-2 agonists cause respiratory smooth muscle to relax.

44. Norepi feedbacks and inhibits the presynaptic receptor by What mechanism
Binding to the presynaptic alpha 2 release modulating receptors
- Atropine & pralidoxime
Blocking muscarinic receptors in the circular fibers of the eye - results in unopposed action of radial muscles to dilate.
Premature infants - because they lack UDP- glucuronyl transferase

45. Name some common Sulfonamides (4)
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis
- Ethosuxamide - sulfonamides - lamotrigine
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine

46. For Heparin What is the Lab value to monitor
aPTT (intrinsic pathway)
Butyrophenone (neuroleptic).
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis
amphetamine and ephedrine

47. Decrease Digitoxin dose in renal failure?
Yes
To inhibit renal Dihydropeptidase I and decrease Imipenem inactivation in the renal tubules
Epinephirine(Alpha1 -2 and Beta 1 -2)
NO

48. What is the category of drug names ending in - terol (e.g. Albuterol)
Beta -2 agonist.
Neutropenia
blocks SR Ca2+ channels
Pseudomonas species and Gram - rods

49. What is an occasional side effect of Aztreonam?
GI upset
Bleeding.
Depolymerizes microtubules - impairing leukocyte chemotaxis and degranulation.
Acute gout.

50. Explain pH dependent urinary drug elimination?
Sildenafil fills the penis
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval
Phenothiazine (neuroleptic - antiemetic).