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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. Why is carbachol and pilocarpine useful in treatment of glaucoma?
Blood
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.
Rheumatoid and osteoarthritis.
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).

2. Quinidine - toxicity?
- Estrogen receptor antagonist - Breast CA - increased endometrial CA risk
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval
Minor hepatotoxicity - Drug interactions (activates P450)
ARF - shock - drug overdose - decrease intracranial/intraocular pressure

3. Adverse effects of Clonidine?
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).
Reversible block of histamine H2 receptors
With supplemental Folic Acid
dry mouth - sedation - severe rebound hypertension

4. Name some common Sulfonamides (4)
Minor hepatotoxicity - Drug interactions (activates P450)
Flutamide is a nonsteroidal competitive inhibitor of androgens at the testosterone receptor - used in prostate carcinoma.
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis

5. For Warfarin What is the Duration of action
- Steroids - Tamoxifen
Chronic (weeks or months)
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis
bradycardia - AV block - CHF

6. Name four HMG- CoA reductase inhibitors.
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine
Phosphorylation by a Viral Kinase
Lovastatin - Pravastatin - Simvastatin - Atorvastatin
Scopolamine

7. Which diuretics increase urine K+?
Antileukotriene; blocks leukotriene receptors.
1. Addison's disease 2. Inflammation 3. Immune suppression 4. Asthma
all except the K+ sparing diuretics Spironolactone - Triamterene - Amiloride
Milk or Antacids - because divalent cations inhibit Tetracycline absorption in the gut

8. Digoxin v. Digitoxin: half life?
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens
Antibiotic - protein synthesis inhibitor.
Digitoxin 168hrs Digoxin 40 hrs
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention

9. What is the category of drug names ending in - caine (e.g. Lidocaine)
Same as penicillin. Extended spectrum antibiotics
- Alkalate DNA - Brain tumors - CNS toxicity
Local anesthetic.
- Ammonium Chloride

10. What are two types of drugs that interfere with the action of Sucralfate and why?
thick ascending limb
Sucralfate cannot work in the presence of antacids or H2 blockers because it requires an acidic environment to polymerize.
Pentamidine
- Nitrate - hydroxocobalamin thiosulfate

11. What is the mechanism of action and clinical use of the antiandrogen Flutamide?
- B51Naloxone / naltrexone (Narcan)
Flutamide is a nonsteroidal competitive inhibitor of androgens at the testosterone receptor - used in prostate carcinoma.
cyanide toxicity (releases CN)
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.

12. How would hemicholinium treatment affect cholinergic neurons?
Blastomyces - Coccidioides - Histoplasma - C. albicans; Hypercortisolism
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.
Acute (hours)
Hemicholinium inhibits the transport of choline into the nerve - thus inhibiting formation of ACh.

13. Which drug(s) cause this reaction: Cinchonism (2)?
- Quinidine - quinine
Inhibits reabsorption of uric acid.
Pretreat with antihistamines and a slow infusion rate
Megaloblastic anemia - Leukopenia - Granulocytopenia

14. What enzyme is responsible for the production of Ach from Acetyl CoA and Choline
proximal convoluted tubule - thin descending limb - and collecting duct
- Act on same receptor - Full has greater efficacy
PT
Choline acetyltransferase

15. What is the mechanism of action of Sildenafil (Viagra)?
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids
Chronic (weeks or months)
Inhibits cGMP phosphodiesterase - casuing increased cGMP - smooth muscle relaxation in the corpus cavernosum - increased blood flow - and penile erection.
decrease

16. What is the mechanism of action of Misoprostol?
Penicillin - Ampicillin - Ticarcillin - Pipercillin - Imipenem - Aztreonam - Cephalosporins
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow
- Flumazenil
Misoprostol is a PGE1 analog that increases the production and secretion of the gastic mucous barrier.

17. Foscarnet does not require activation by a...
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.
Pregnant women - Children; because animal studies show Damage to Cartilage
Digitoxin>95% Digoxin 75%
viral kinase

18. How is Trimethoprim used clinically?
Used in combination therapy with SMZ to sequentially block folate synthesis
Disulfiram - like reaction with EtOH - Headache
blocks SR Ca2+ channels
The PT.

19. What is the mechanism of action of Heparin?
Ca2+ (Loops Lose calcium)
Decreases synthesis of Mycolic Acid
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors
Heparin catalyzes the activation of antithrombin III.

20. Name five Antiarrhythmic drugs in class II?
Prefers beta's at low doses - but at higher doses alpha agonist effects are predominantly seen.
Useful in muscle paralysis during surgery or mechanical ventilation.
1. Addison's disease 2. Inflammation 3. Immune suppression 4. Asthma
propanolol - esmolol - metoprolol - atenolol - timolol

21. Guanethidine enhances the release of Norepi?
- Vinca alkaloids(inhibit MT) - Paclitaxel
- Vitamin K & fresh frozen plasma
Beta - lactam antibiotics
No - it inhibits the release of Nor Epi

22. Mannitol - clinical use?
- Oxalic acid - Acidosis & nephrotoxicity
- Ammonium Chloride
H2 antagonist
ARF - shock - drug overdose - decrease intracranial/intraocular pressure

23. Name three ACE inhibitors?
NO AP duration effect. useful in V- tach that progresses to V- fib and in intractable SVT Last RESORT
- Tricyclic antidepressants
Same as penicillin. Extended spectrum antibiotics
Captopril - Enalapril - Lisinopril

24. What is combined with Ampicillin - Amoxicillin - Carbenicillin - Piperacillin - and Ticarcillin to enhance their spectrum?
Competitive inibitor of progestins at progesterone receptors.
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility
Clavulanic acid
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased

25. What are four clinical uses of glucocorticoids?

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26. For Warfarin What is the Mechanism of action
Impairs the synthesis of vitamin K- dependent clotting factors
cardiac depression - peripheral edema - flushing - dizziness - constipation
hypertrichosis - pericardial effusion - reflex tachycardia - angina - salt retention
Because they require some residual islet function.

27. What is the clinical use of Mifepristone (RU486)?
Blocks Influenza A and RubellA; causes problems with the cerebellA
proarrhythmic
Abortifacient.
Hypersensitivity reactions

28. How is Ribavirin used clinically?
- Methotrexate - 5 FU - 6 mercaptopurine
proximal convoluted tubule
for RSV
- Chlorpromazine - thioridazine - haloperidol

29. Are penicillinase resistant
Severe Gram - rod infections.
Staphlococcus aureus and Clostridium difficile (pseudomembranous colitis)
anuria - CHF
Methicillin - Nafcillin - and Dicloxacillin

30. What is the category of drug names ending in - barbital (e.g. Phenobarbital)
- Phase I (clinical tests) - Phase II - Phase III - PhaseIV (surveillance)
Babiturate.
Prevents release of mediators from mast cells. Effective only for the prophylaxis of asthma. Not effective during an acute attack.
proximal convoluted tubule - thin descending limb - and collecting duct

31. What is the clinical use for Warfarin?
Hypersensitivity reactions
Chronic anticoagulation.
Interferes with microtubule function - disrupts mitosis - inhibits growth
- Alkalinize urine & dialysis

32. Ca2+ channel blockers - mechanism?
- Penicillin
BM suppression (neutropenia - anemia) - Peripheral neuropathy
- Physostigmine salicylate
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility

33. What are common toxicities associated with Tetracyclines?

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34. What are the nondepolarizing neuromuscular blocking drugs?
Treatment of hypertension - especially with renal disease (lowers bp centrally - so flow is maintained to kidney).
HTN - CHF - calcium stone formation - nephrogenic DI.
hyperchloremic metabolic acidosis - neuropathy - NH3 toxicity - sulfa allergy
Tubocurarine - atracurium - mivacurium - pancuronium - vecuronium - rapacuronium

35. What is the MOA for Carbenicillin - Piperacillin - and Ticarcillin?
- Halothane - Valproic acid - acetaminophen - Amantia phalloides
Blocks viral penetration/uncoating; may act to buffer the pH of the endosome
Pituitary hormone.
Same as penicillin. Extended spectrum antibiotics

36. Which drug(s) cause this reaction: Oto and Nephrotoxicity (3)?
Protease Inhibitors and Reverse Transcriptase Inhibitors
- Oxalic acid - Acidosis & nephrotoxicity
- aminoglycosides - loop diuretics - cisplatin
- Dimercaprol - succimer

37. List the specific antidote for this toxin: Iron
- Deferoxamine
Pralidoxime regenerates active cholinesterase.
- Clindamycin
Irreversibly inhibits H+/K+ ATPase in stomach parietal cells.

38. Resistance mechanisms for Sulfonamides
Cardiac glycoside (inotropic agent).
Penicillin - Ampicillin - Ticarcillin - Pipercillin - Imipenem - Aztreonam - Cephalosporins
- Hypersensitivity reactions - Hemolysis - Nephrotoxicity (tubulointerstitial nephritis) - Kernicterus in infants Displace other drugs from albumin (e.g. - warfarin)
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis

39. What are toxic side effects for Metronidazole?
- Antipsychotics
- Flumazenil
Well tolerated in general but occasionally - Nephrotoxicity - Ototoxicity - Thrombophlebitis - diffuse flushing='Red Man Syndrome'
Disulfiram - like reaction with EtOH - Headache

40. What is the possible mechanism and effect of Metformin in treating diabetes?
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels
Benzathine penicillin G
- Clindamycin
- Cloazapine - carbamazapine - colchicine - PTU

41. Mg+- clinical use?
Rifampin (DOC) - minocycline
Tendonitis and Tendon rupture
effective in torsade de pointes and digoxin toxicity
Increases coumadin metabolism

42. Reserpine will block the syntheis of this drug and but not its precursor.
Blocks Norepi - but not Dopamine
Pralidoxime regenerates active cholinesterase.
- Penicillin
cross - allergenic

43. Hydralazine - class and mechanism?
depresses ectopic pacemakers - especially in digoxin toxicity
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia
Amphetamine and Ephedrine
vasodilator - increases cGMP to induce smooth muscle relaxation (arterioles>veins; afterload reduction)

44. What are five toxicities associated with Tacrolimus (FK506)?
Misoprostol is a PGE1 analog that increases the production and secretion of the gastic mucous barrier.
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more
Nephrotoxicity (esp. with Cephalosporins) - Ototoxicity (esp. with Loop Diuretics)

45. Name two classes of drugs for HIV therapy
Antileukotriene; blocks synthesis by lipoxygenase.
Protease Inhibitors and Reverse Transcriptase Inhibitors
Scopolamine
Reversible block of histamine H2 receptors

46. Acetaldehyde is metabolized by Acetaldehyde dehydrogenase - Which drug inhibs this enzyme?
- Disulfram & also sulfonylureas - metronidazole
No - hemicholinum block the uptake of Choline and thus Ach synthesis
Erectile dysfunction.
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.

47. Which drug(s) cause this reaction: Gingival hyperplasia?
anuria - CHF
Ciprofloxacin - Norfloxacin - Ofloxacin - Grepafloxacin - Enoxacin - Nalidixic acid
With an amino acid change of D- ala D- ala to D- ala D- lac
- Phenytoin

48. What is the category of drug names ending in - olol (e.g. Propranolol)
Slow - limited by half lives of clotting factors
- MT polymerization inhibitor(M phase) - MOPP - lymphoma - Willm's & choriocarcinoma - neurotoxicity and myelosuppression
Beta antagonist.
- Class III antiarrhythmics (sotalol) - class IA (quinidine)

49. Adverse effects of Hydrochlorothiazide?
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.
severe hypertension - CHF
Forms toxic metabolites in the bacterial cell - Bactericidal
hypokalemia - slight hyperlipidemia - hyperuricemia - lassitude - hypercalcemia - hyperglycemia

50. What is the category - desired effect - and period of use of albuterol in the treatment of Asthma?
GI discomfort
- Atropine & pralidoxime
Succinylcholine
Beta 2 agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Use during acute exacerbation.