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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. Adverse effects of Prazosin?
Give an antichloinesterase - neostigmine - edrophonium - etc
first dose orthostatic hypotension - dizziness - headache
G6PD deficient individuals
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome

2. Which drug(s) cause this reaction: Anaphylaxis?
- Penicillin
Cell membrane Ca2+ channels of cardiac sarcomere
No - it inhibits the release of Nor Epi
No

3. What is the mechanism of action of Sildenafil (Viagra)?
Hypersensitivity reactions
Inhibits cGMP phosphodiesterase - casuing increased cGMP - smooth muscle relaxation in the corpus cavernosum - increased blood flow - and penile erection.
Hydralazine and Minoxidil
Spironolactone - Triamterene - Amiloride (the K+ STAys)

4. What is the category of drug names ending in - pril (e.g. Captopril)
vasodilator - increases cGMP to induce smooth muscle relaxation (arterioles>veins; afterload reduction)
Topical and Oral - for Oral Candidiasis (Thrush)
Chronic gout.
ACE inhibitor.

5. Resistance mechanisms for Vancomycin
In 4 half - lifes= (94%) T1/2 = (0.7x Vd)/CL
Decreased uptake or Increased transport out of cell
1. Meningococcal carrier state 2. Chemoprophylaxis in contacts of children with H. influenzae type B
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity

6. Ethacrynic Acid - clinical use?
Lipoxygenase
Succinylcholine
Diuresis in pateints with sulfa allergy
GI distress - Tooth discoloration and Inhibition of bone growth in children - Fanconi's syndrome - Photosensitivity

7. Which drug(s) cause this reaction: P450 induction(6)?
Binds to the Pyrophosphate Binding Site of the enzyme
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine
Saquinavir - Ritonavir - Indinavir - Nelfinavir
vascular sm. Mus.: Nifedipine>Diltiazem>Verapamil

8. What effect would atropine have on a patient with peptic ulcer disease?
Rifampin (DOC) - minocycline
No - it inhibits the release of Nor Epi
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).
Nevirapine - Delavirdine

9. Resistance mechanisms for Macrolides

10. What is the MOA for the Macrolides?
- Glucagon
Verapamil - Diltiazem - Bepridil
Dermatophytes (tinea - ringworm)
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic

11. What is an additional side effect of Methicillin?
Interstitial nephritis
GI upset
Hexamethonium is a nicotinic antagonist - and thus is a ganglionic blocker.
NO HYPERURICEMIA - NO SULFA AllERGY; same as furosemide otherwise

12. What are the clinical uses for Imipenem/cilastatin?
prevention of nodal arrhythmias (SVT)
Benzathine penicillin G
very short acting
Gram + cocci - Gram - rods - and Anerobes

13. What parasitic condition is treated with Ivermectin?

14. What is the receptor affinity and clinical use of isoproterenol?
hyperchloremic metabolic acidosis - neuropathy - NH3 toxicity - sulfa allergy
- Cloazapine - carbamazapine - colchicine - PTU
Hypersensitivity reactions
It affects beta receptors equally and is used in AV heart block (rare).

15. What is the main clinical use for the thrombolytics?
Early myocardial infarction.
Increased systolic and pulse pressure - decreased diastolic pressure - and little change in mean pressure.
Chronic Hepatitis A and B - Kaposi's Sarcoma
Beta1 more than B2

16. What are five disadvantages of Oral Contraceptives (synthetic progestins - estrogen)?
Ciprofloxacin - Norfloxacin - Ofloxacin - Grepafloxacin - Enoxacin - Nalidixic acid
1. Taken daily 2. No protection against STDs 3. Raises triglycerides 4. Depression - weight gain - nausea - HTN 5. Hypercoagulable state
Chagas' disease - American Trypanosomiasis (Trypanosoma cruzi)
GI side effects. (Indomethacin is less toxic - more commonly used.)

17. What are signs of Sildenafil (Viagra) toxicity?
- Clindamycin
proximal convoluted tubule - thin descending limb - and collecting duct
Headache - flushing - dyspepsia - blue - green color vision.
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.

18. How do spare receptors effect the Km?
propanolol - esmolol - metoprolol - atenolol - timolol
- ED 50 is less than the Km (less than 50% of receptors)
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval

19. What is the MOA of Isoniazid (INH)?
ACIDazolamide' causes acidosis
Dermatophytes (tinea - ringworm)
Decreases synthesis of Mycolic Acid
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.

20. In What population does Gray Baby Syndrome occur? Why?
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.
Premature infants - because they lack UDP- glucuronyl transferase
- Phenytoin
Pentamidine

21. Adenosine - clinical use?
Aminoglycosides
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.
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels
DOC in diagnosing and abolishing AV nodal arrhythmias

22. What is a common side effect of Colchicine used to treat acute gout - especially When given orally?
GI side effects. (Indomethacin is less toxic - more commonly used.)
Lipoxygenase
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow
GI discomfort

23. Which drug(s) cause this reaction: Drug induced Parkinson's (4) ?
Slow - limited by half lives of clotting factors
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.
- Haloperidol - chlorpromazine - reserpine - MPTP
No - it inhibits the release of Nor Epi

24. For Warfarin What is the Route of administration
- Isoniazid
Hydralazine and Minoxidil
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow
Oral

25. What are five toxicities associated with Tacrolimus (FK506)?
- inhibits HGPRT (pur. Syn.) - Luk - Lymph
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.
1. Hypoglycemia (more common with 2nd - generation drugs: glyburide - glipizide) 2. Disulfiram - like effects (not seen with 2nd - generation drugs).
fetal renal damage - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)

26. What is the MOA for the Azoles?
Inhibit Ergosterol synthesis
- reduction - oxy - & hydrolysis - H2O sol. Polar product - P450
Aplastic anemia (dose independent) - Gray Baby Syndrome
Protease inhibitor.

27. List the mechanism - clinical use - & toxicity of Bleomycin.
- DNA intercalator - testicular & lymphomas - Pulmonary fibrosis mild myelosuppression.
Prophylaxis for Influenza A - Rubella; Parkinson's disease
viral kinase
Delirium - Tremor - Nephrotoxicity

28. What is the clinical utility of cocaine?
- N- acetylcystine
Cell membrane Ca2+ channels of cardiac sarcomere
The only local anesthetic with vasoconstrictive properties.
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.

29. For Warfarin What is the Onset of action
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility
Slow - limited by half lives of clotting factors

30. Aztreonam is not ________ with penicillins
cross - allergenic
Butyrophenone (neuroleptic).
check PFTs - LFTs - and TFTs
Nephrotoxicity (esp. with Cephalosporins) - Ototoxicity (esp. with Loop Diuretics)

31. When is HIV therapy initiated?
When pts have Low CD4+ (< 500 cells/cubic mm) or a High Viral Load
Non - Nucleosides
- Shifts the curve down - reduces Vmax
Lidocaine - Mexiletine - Tocainide

32. How does a noncompetitive antagonist effect an agonist?
blocks SR Ca2+ channels
- Oral Contraceptives
- Shifts the curve down - reduces Vmax
Ceftriaxone

33. What is action of insulin in the liver - in muscle - and in adipose tissue?
Those patients who are taking nitrates.
viral kinase
Beta adrenergic receptors and Ca2+ channels (stimulatory)
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.

34. What are toxicities associated with Chloramphenicol?
Aplastic anemia (dose independent) - Gray Baby Syndrome
alpha -1 > alpha -2; used as a pupil dilator - vasoconstrictor - and for nasal decongestion
- Vinca alkaloids(inhibit MT) - Paclitaxel
1. Streptokinase 2. Urokinase 3. tPA (alteplase) - APSAC (anistreplase)

35. Describe Phase II metabolism in liver(3)?
depresses ectopic pacemakers - especially in digoxin toxicity
- acetylation - glucuron. - & sulfation - Conjugation - Polar product
Ceftriaxone
- inhibits HGPRT (pur. Syn.) - Luk - Lymph

36. What type of gout is treated with Allopurinol?
- Alkalate DNA - Brain tumors - CNS toxicity
Overdose produces hepatic necrosis; acetaminophen metablolite depletes glutathione and forms toxic tissue adducts in liver.
No
Chronic gout.

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

38. List the mechanism - clinical use - & toxicity of Busulfan.
Polymyxin B - Polymyxin E
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.
- Alkalates DNA - CML - Pulmonary fibrosis hyperpigmentation
Staphlococcus aureus and Clostridium difficile (pseudomembranous colitis)

39. For Heparin What is the Mechanism of action
Inhibit viral DNA polymerase
Activates antithrombin III
- Haloperidol - chlorpromazine - reserpine - MPTP
new arrhythmias - hypotension

40. What is the formula for Volume of distribution (Vd)
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.)
Vd= (Amt. of drug in body/ Plasma drug conc.)
Protease Inhibitors and Reverse Transcriptase Inhibitors
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity

41. What is the category of drug names ending in - phylline (e.g. Theophylline)
Beta antagonist.
Methylxanthine.
- Flumazenil
Beta adrenergic receptors and Ca2+ channels (stimulatory)

42. What is a sign of toxicity with the use of thrombolytics?
Indomethacin is used to close a patent ductus arteriosus.
GI side effects. (Indomethacin is less toxic - more commonly used.)
Bleeding.
blocks SR Ca2+ channels

43. K+- clinical use?
Hemolytic anemia
Blocking muscarinic receptors in the circular fibers of the eye - results in unopposed action of radial muscles to dilate.
depresses ectopic pacemakers - especially in digoxin toxicity
With an amino acid change of D- ala D- ala to D- ala D- lac

44. What enzyme is responsible for the breakdown of ACh in the synaptic cleft?
Acute (hours)
Disulfiram - like reaction with EtOH - Headache
Acetylcholinesterase; ACh is broken down into choline and acetate.
- Acetaldehyde - Nausea - vomiting - headache - & hypotension

45. What enzyme is responsible for the degredation of Ach
Acetylcholine esterase
1. Better bioavailability 2. 2 to 4 times longer half life 3. Can be administered subcutaneously 4. Does not require laboratory monitoring
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.

46. What is the MOA of Aztreonam?
Inhibits cell wall synthesis ( binds to PBP3). A monobactam
BM suppression (neutropenia - anemia) - Peripheral neuropathy
1. Meningococcal carrier state 2. Chemoprophylaxis in contacts of children with H. influenzae type B
cyanide toxicity (releases CN)

47. What is are two clinical uses of Cyclosporine?
Early myocardial infarction.
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.
1)Binds penicillin - binding proteins 2) Blocks transpeptidase cross - linking of cell wall 3) Activates autolytic enzymes
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.

48. Side effects of Isoniazid (INH)?
propanolol - esmolol - metoprolol - atenolol - timolol
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome
Fever/Chills - Hypotension - Nephrotoxicity - Arrhythmias
Interstitial nephritis

49. Mannitol - site of action?
No - warfarin - unlike heparin - can cross the placenta.
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.
Hemicholinium inhibits the transport of choline into the nerve - thus inhibiting formation of ACh.
proximal convoluted tubule - thin descending limb - and collecting duct

50. How can Vancomycin - induced 'Red Man Syndrome' be prevented?
- Vinca alkaloids(inhibit MT) - Paclitaxel
Pretreat with antihistamines and a slow infusion rate
Methicillin - Nafcillin - and Dicloxacillin
Inhibition of 50S peptidyl transferase - Bacteriostatic