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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. What is the clinical use of Mifepristone (RU486)?
Interstitial nephritis
Abortifacient.
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.

2. What is the MOA of Ganciclovir?
Inhibits Viral DNA polymerase
Oxygen
Inhibits CMV DNA polymerase
penicillinase resistant

3. What is the major toxic side effect of Penicillin?
1. RNA pol inhibitor 2. Revs up P450 3. Red/orange body fluids 4. Rapid resistance if used alone
Hypersensitivity reactions
Nucleosides
Protamine sulfate

4. What is the memory key for the action of Sildenafil (Viagra)?
1. Better bioavailability 2. 2 to 4 times longer half life 3. Can be administered subcutaneously 4. Does not require laboratory monitoring
Prevents the release of ACh - Which results in muscle paralysis.
Sildenafil fills the penis
Interstitial nephritis

5. Which drug(s) cause this reaction: Focal to massive hepatic necrosis (4)?
- Hypersensitivity reactions - Hemolysis - Nephrotoxicity (tubulointerstitial nephritis) - Kernicterus in infants Displace other drugs from albumin (e.g. - warfarin)
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.
- Halothane - Valproic acid - acetaminophen - Amantia phalloides
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.

6. What is the MOA for Ampicillin and Amoxicillin?
Pyridoxine (B6) administration
Neutropenia
Same as penicillin. Extended spectrum antibiotics
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.

7. What are five possible toxic effects of Aspirin therapy?

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8. List the specific antidote for this toxin: Cyanide
Anaerobes
Pituitary hormone.
Gram + cocci - Haemophilus influenza - Enterobacter aerogenes - Neisseria species - P. mirabilis - E. coli - K. pneumoniae - Serratia marcescens ( HEN PEcKS )
- Nitrate - hydroxocobalamin thiosulfate

9. Antiarrhythmic class IC- effects?
Doxycycline - because it is fecally eliminated
hyperaldosteronism - K+ depletion - CHF
Treatment of hypertension - especially with renal disease (lowers bp centrally - so flow is maintained to kidney).
NO AP duration effect. useful in V- tach that progresses to V- fib and in intractable SVT Last RESORT

10. What is the chemical name for Ganciclovir?
Acute (hours)
collecting ducts
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.
DHPG (dihydroxy-2- propoxymethyl guanine)

11. What is the MOA for the Azoles?
Inhibit Ergosterol synthesis
1. Streptokinase 2. Urokinase 3. tPA (alteplase) - APSAC (anistreplase)
anticholinesterase glaucoma
Peptic ulcer disease.

12. What is the category and mechanism of action of Zafirlukast in Asthma treatment?
Antileukotriene; blocks leukotriene receptors.
Liver
1) Chloramphenical = bacteriostatic 2) Erythromycin = bacteriostatic 3) Lincomycin = bacteriostatic 4)cLindamycin = bacteriostatic
- Tamoxifen

13. Are not penicillinase resistant
- Phase I (clinical tests) - Phase II - Phase III - PhaseIV (surveillance)
Carbenicillin - Piperacillin - and Ticarcillin
Inhibits cell wall synthesis ( binds to PBP3). A monobactam
- Vitamin K & fresh frozen plasma

14. What should not be taken with Tetracyclines? / Why?
- Tricyclic antidepressants
- Corticosteroids - heparin
Milk or Antacids - because divalent cations inhibit Tetracycline absorption in the gut
Phenothiazine (neuroleptic - antiemetic).

15. What is a sign of toxicity with the use of thrombolytics?
Bleeding.
fetal renal toxicity - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
Staphlococcus aureus
Methylxanthine.

16. What is the mechanism of Azathioprine?
Antimetabolite derivative of 6- mercaptopurine that interferes with the metablolism and synthesis of nucleic acid.
decrease the slope of phase 4 - increase PR interval (the AV node is particularly sensitive)
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.
Activates antithrombin III

17. What microorganisms are clinical indications for Tetracycline therapy?

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18. Which individuals are predisposed to Sulfonamide - induced hemolysis?
Blastomyces - Coccidioides - Histoplasma - C. albicans; Hypercortisolism
G6PD deficient individuals
- MT polymerization inhibitor(M phase) - MOPP - lymphoma - Willm's & choriocarcinoma - neurotoxicity and myelosuppression
In treatment of malignant hyperthermia - due to concomitant use of halothane and succinylcholine. Also in neuroleptic malignant syndrome - a toxicity of antipsychotic drugs.

19. For Warfarin What is the Onset of action
troponin - tropomyosin system
Slow - limited by half lives of clotting factors
Ipratropium
1. Better bioavailability 2. 2 to 4 times longer half life 3. Can be administered subcutaneously 4. Does not require laboratory monitoring

20. How do you treat coma in the ER (4)?
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.
- Airway - Breathing - Circulation - Dextrose (thiamine & narcan) - ABCD
hyperchloremic metabolic acidosis - neuropathy - NH3 toxicity - sulfa allergy
hypokalemia - slight hyperlipidemia - hyperuricemia - lassitude - hypercalcemia - hyperglycemia

21. How would you treat African Trypanosomiasis (sleeping sickness)?
- Alkalinize urine & dialysis
Reserpine inhibits dopamine transport into vesicles - attenuating its conversion to NE by dopamine beta - hydroxylase.
Staphlococcus aureus and Clostridium difficile (pseudomembranous colitis)
Suramin

22. What is Nifurtimox administered for?

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23. What is the category of drug names ending in - azine (e.g. Chlorpromazine)
viral kinase
Phenothiazine (neuroleptic - antiemetic).
Quinidine - Amiodarone - Procainamide - Disopyramide
- Haloperidol - chlorpromazine - reserpine - MPTP

24. What are the Macrolides used for clinically?
- Upper respiratory tract infections - pneumonias - STDs: Gram+ cocci (streptococcal infect in pts allergic to penicillin) - Mycoplasma - Legionella - Chlamydia - Neisseria
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
Misoprostol is a PGE1 analog that increases the production and secretion of the gastic mucous barrier.

25. Mannitol - toxicity?
depresses ectopic pacemakers - especially in digoxin toxicity
IV vitamin K and fresh frozen plasma
Can affect absorption - bioavailability - or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying.
pulmonary edema - dehydration

26. How does a noncompetitive antagonist effect an agonist?
For serious - Gram + multidrug - resistant organisms
Antileukotriene; blocks leukotriene receptors.
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic
- Shifts the curve down - reduces Vmax

27. List the specific antidote for this toxin: Tricyclic antidepressants
No - hemicholinum block the uptake of Choline and thus Ach synthesis
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic
- NaHCO3
- Alkalinize urine & dialysis

28. What are the major structural differences between Penicillin and Cephalosporin?
- ACE inhibitors (Losartan>no cough)
Cephalosporin: 1) has a 6 member ring attached to the Beta lactam instead of a 5 member ring 2)has an extra functional group ( attached to the 6 member ring)
- S- phase anti - metabolite folate analogue - Luk - Lymp - sarc - RA - & psoriasis / - Reversible myelosuppression
Gemfibrozil - Clofibrate

29. Which drug(s) cause this reaction: Gingival hyperplasia?
Epinephirine(Alpha1 -2 and Beta 1 -2)
orthostatic and exercise hypotension - sexual dysfunction - diarrhea
- Phenytoin
hypertrichosis - pericardial effusion - reflex tachycardia - angina - salt retention

30. What is the lab value used to monitor the effectiveness of Heparin therapy?
troponin - tropomyosin system
Misoprostol is contraindicated in women of childbearing potential because it is an abortifacient.
The PTT.
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).

31. What are two toxicities of the Glitazones?
No - hemicholinum block the uptake of Choline and thus Ach synthesis
Choline acetyltransferase
1. Weight gain 2. Hepatotoxicity (troglitazone)
Neomycin

32. Do Tetracyclines penetrate the CNS?
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.
Only in limited amounts
Hypersensitivity reactions
Slow - limited by half lives of clotting factors

33. Which of these three drugs will cause a reflex bradycardia in your pt (Norepi - Epi - or Isoporterenol)
Cimetidine is a potent inhibitor of P450; it also has an antiandrogenic effect and decreases renal excretion of creatinine. Other H2 blockers are relatively free of these effects.
- Tricyclic antidepressants
Norepinephrine
Penicillin - G

34. Which drug(s) cause this reaction: Cardiac toxicity?
DOC in diagnosing and abolishing AV nodal arrhythmias
- Daunorubicin & Doxorubicin
Ibuprofen - Naproxen - and Indomethacin
It acts presynaptically to increase NE release.

35. What parasites are treated with Pyrantel Pamoate (more specific)?
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
Flecainide - Encainide - Propafenone
Inhibit steroid synthesis - used in the treatment of polycystic ovarian syndrome to prevent hirsutism.
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens

36. What is the mechanism of action of the Alpha - glucosidase inhibitors?
Due to the presence of a bulkier R group
Long.
cardiac depression - peripheral edema - flushing - dizziness - constipation
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.

37. How can Vancomycin - induced 'Red Man Syndrome' be prevented?
- Chlorpromazine - thioridazine - haloperidol
Pretreat with antihistamines and a slow infusion rate
1. Renal damage 2. Aplastic anemia 3. GI distress
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia

38. What is the formula for Clearance (CL)
- Alkalinize urine & dialysis
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
CL= (rate of elimination of drug/ Plasma drug conc.)

39. Where does Griseofulvin deposit?
Keratin containing tissues - e.g. - nails
Inhibits Viral DNA polymerase
hypertrichosis - pericardial effusion - reflex tachycardia - angina - salt retention
Anaerobes

40. What are common toxicities associated with Tetracyclines?

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41. What is Imipenem always administered with?
dizziness - flushing - constipation (verapamil) - nausea
It inhibits release of NE.
Prevents the release of ACh - Which results in muscle paralysis.
Cilastatin

42. What are the clinical uses for 3rd Generation Cephalosporins?
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)
check PFTs - LFTs - and TFTs
Meningitis (H. influenza - N. meningitidis - S. pneumoniae) - Conserative treatment due to toxicities
Protamine sulfate

43. What is the mechanism of action of the thrombolytics?
- Glucagon
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.)
Milk or Antacids - because divalent cations inhibit Tetracycline absorption in the gut
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.

44. What is the MOA for Methicillin - Nafcillin - and Dicloxacillin?
Cephalosporin: 1) has a 6 member ring attached to the Beta lactam instead of a 5 member ring 2)has an extra functional group ( attached to the 6 member ring)
Post - op and neurogenic ileus and urinary retention - myasthenia gravis - and reversal of neuromuscular junction blockade (post - op) through anticholinesterase activity.
Same as penicillin. Act as narrow spectrum antibiotics
glaucoma - urinary alkalinization - metabolic alkalosis - altitude sickness

45. What are Methicillin - Nafcillin - and Dicloxacillin used for clinically?
- Methotrexate - 5 FU - 6 mercaptopurine
Primaquine
Suramin
Staphlococcus aureus

46. What is the loading dose formula?
Similar to cyclosporine; binds to FK- binding protein - inhibiting secretion of IL-2 and other cytokines.
Captopril - Enalapril - Lisinopril
Ld= (CpxVd)/F Cp=plasma conc. F= Bioaval.
Chronic anticoagulation.

47. A group of pts are rushed into the ER complaining of excessive sweating - tearing - salivation - HA - N and V - muscle twitching - difficulty breathing and diarrhea. What drug would be the most effective immediate tx
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.)
Bismuth and Amoxicillin or Tetracycline; against Helobacter pylori
1. Antiandrogen 2. Nausea 3. Vomiting
Atropine pts are suffering from Cholinestrase inhibitor poisining (Nerve gas/Organophosphate poisining)

48. Ca2+ sensitizers'- site of action?
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors
troponin - tropomyosin system
Beta adrenergic receptors and Ca2+ channels (stimulatory)
Epinephirine(Alpha1 -2 and Beta 1 -2)

49. List the specific antidote for this toxin: Iron
Prevention of NSAID- induced peptic ulcers - maintains a PDA.
- N- acetylcystine
- Deferoxamine
decrease AP duration - affects ischemic or depolarized Purkinje and ventricular system

50. Name common Polymyxins
Polymyxin B - Polymyxin E
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.
Nephrotoxicity
- S- phase anti - metabolite folate analogue - Luk - Lymp - sarc - RA - & psoriasis / - Reversible myelosuppression