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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. How is Ganciclovir activated?
Phosphorylation by a Viral Kinase
1) Hypersensitivity reactions 2) Increased nephrotoxicity of Aminoglycosides 3) Disulfiram - like reaction with ethanol (those with a methylthiotetrazole group - e.g. - cefamandole)
thiazides - amiloride
Cardiac glycoside (inotropic agent).

2. Name the common Non - Nucleoside Reverse Transcriptase Inhibitors
Phenothiazine (neuroleptic - antiemetic).
Pentamidine
Nevirapine - Delavirdine
They inhibit reuptake of NE at the nerve terminal (as does cocaine).

3. What are four conditions in Which H2 Blockers are used clinically?
Anaerobes
- aminoglycosides - loop diuretics - cisplatin
No. Atropine is used to reduce urgency in mild cystitis. So it would aggravate the urinary retention.
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome

4. What is the category of drug names ending in - azepam (e.g. Diazepam)
Antifungal.
Benzodiazepine.
is resistant
Only in limited amounts

5. What cholinomimetics might your pt be taking for his glaucoma
Rifampin
Carbachol - pilocarpine - physostigmine - echothiophate
blocks SR Ca2+ channels
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors

6. Are not penicillinase resistant
Same as penicillin. Extended spectrum antibiotics
Carbenicillin - Piperacillin - and Ticarcillin
- Metronidazole - certain cephalosporins - procarbazine - sulfonylureas
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time

7. Acetazolamide - site of action?
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.
proximal convoluted tubule
1. Streptokinase 2. Urokinase 3. tPA (alteplase) - APSAC (anistreplase)
With an amino acid change of D- ala D- ala to D- ala D- lac

8. Ca2+ channel blockers - mechanism?
Methylzanthine; desired effect is bronchodilation - may cause bronchodilation by inhibiting phosphodiesterase - enzyme involved in degrading cAMP (controversial).
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility
- Shifts the curve to the right - increases Km
1. Better bioavailability 2. 2 to 4 times longer half life 3. Can be administered subcutaneously 4. Does not require laboratory monitoring

9. Which individuals are predisposed to Sulfonamide - induced hemolysis?
G6PD deficient individuals
- Ammonium Chloride
Penicillin - V
AmOxicillin has greater Oral bioavailability

10. What sympathomimetic would you not prescribe for hypotension in a pt with renal artery sclerosis.
Norepinephrine (Alpha1 -2 and beta 1)
Digitoxin>95% Digoxin 75%
- Nitrate - hydroxocobalamin thiosulfate
decrease the slope of phase 4 - increase PR interval (the AV node is particularly sensitive)

11. Sotalol - toxicity?
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.
penicillinase resistant
torsade de pointes - excessive Beta block
- Fluoroquinolones

12. How is Acyclovir used clinically?
HSV - VZV - EBV - Mucocutaneous and Genital Herpes Lesions - Prophylaxis in Immunocompromised pts
- Constant AMOUNT eliminated per unit time. - Etoh & ASA
physostigmine
Yes - it does not cross the placenta.

13. Which antimicrobials inhibit protein synthesis at the 50S subunit? (4)
Blocks Peptide Bond formation at the 50S subunit - Bacteriostatic
Protamine Sulfate is used for rapid reversal of heparinization (positively charged molecule that binds to negatively charged heparin).
1) Chloramphenical = bacteriostatic 2) Erythromycin = bacteriostatic 3) Lincomycin = bacteriostatic 4)cLindamycin = bacteriostatic
- Vinca alkaloids(inhibit MT) - Paclitaxel

14. What enzyme does Zileuton inhibit?
Edrophonium
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine
Lipoxygenase
- Protamine

15. What is the memory key for Metronidazole's clinical uses?
Blocks viral penetration/uncoating; may act to buffer the pH of the endosome
1) Hypersensitivity reactions 2) Increased nephrotoxicity of Aminoglycosides 3) Disulfiram - like reaction with ethanol (those with a methylthiotetrazole group - e.g. - cefamandole)
GET on the Metro
Beta adrenergic receptors and Ca2+ channels (stimulatory)

16. What is the mechanism of Azathioprine?
Rifampin
Antimetabolite derivative of 6- mercaptopurine that interferes with the metablolism and synthesis of nucleic acid.
CMV Retinitis in IC pts When Ganciclovir fails
Bleeding.

17. Beta Blockers - CV toxicity?
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)
Diarrhea - Urination - Miosis - Bronchospasm - Bradycardia - Excitation of skeletal muscle and CNS - Lacrimation - Sweating - and Salivation = DUMBBELS; also abdominal cramping
bradycardia - AV block - CHF
Epinephrine

18. What is the category of drug names ending in - phylline (e.g. Theophylline)
Methylxanthine.
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility
1. Predisposes to viral infections and lymphoma 2. Nephrotoxic (preventable with mannitol diuresis)
Clomiphene is a partial agonist at estrogen receptors in the pituitary gland. Prevents normal feedback inhibition and increses release of LH and FSHfrom the pituitary - Which stimulates ovulation.

19. Side effects of Isoniazid (INH)?
For serious - Gram + multidrug - resistant organisms
Captopril - Enalapril - Lisinopril
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome
Well tolerated in general but occasionally - Nephrotoxicity - Ototoxicity - Thrombophlebitis - diffuse flushing='Red Man Syndrome'

20. Ibutilide - toxicity?
Tricyclic antidepressant.
torsade de pointes
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.
PT

21. Which antimicrobial classes inhibit protein synthesis at the 30S subunit? (2)
1. Gastric ulceration 2. Bleeding 3. Hyperventilation 4. Reye's syndrome 5. Tinnitus (CN VIII)
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic
- Triggers apoptosis - CLL - Hodgkin's in MOPP - Cushing - like syndrome
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.

22. ACE inhibitors - mechanism?
1. Hypoglycemia (more common with 2nd - generation drugs: glyburide - glipizide) 2. Disulfiram - like effects (not seen with 2nd - generation drugs).
GI distress - Tooth discoloration and Inhibition of bone growth in children - Fanconi's syndrome - Photosensitivity
Ld= (CpxVd)/F Cp=plasma conc. F= Bioaval.
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased

23. Adverse effects of Guanethidine?
orthostatic and exercise hypotension - sexual dysfunction - diarrhea
Hydralazine and Minoxidil
Polymyxin B - Polymyxin E
Yes

24. What is the category of drug names ending in - triptyline (e.g. Amitriptyline)
- ACE inhibitors (Losartan>no cough)
Penicillin - Ampicillin - Ticarcillin - Pipercillin - Imipenem - Aztreonam - Cephalosporins
Tricyclic antidepressant.
GI distress - Skin rash - and Seizures at high plasma levels

25. What is the effect of norepinephrine on bp and pulse pressure?
Praziquantel
Increases mean - systolic - and diastolic bp - while there is little change in pulse pressure.
Gram + cocci - Gram - rods - and Anerobes
sedation - positive Coombs' test

26. List the mechanism - clinical use - & toxicity of 5 FU.
- S- phase anti - metabolite Pyr analogue - Colon - solid tumors - & BCC/ - Irreversible myelosuppression
Inhibit DNA Gyrase (topoisomerase II) - Bactericidal
1. Taken daily 2. No protection against STDs 3. Raises triglycerides 4. Depression - weight gain - nausea - HTN 5. Hypercoagulable state
proarrhythmic

27. Name the common Aminoglycosides (5)
Benzodiazepine.
Gentamicin - Neomycin - Amikacin - Tobramycin - Streptomycin
hypertrichosis - pericardial effusion - reflex tachycardia - angina - salt retention
Chronic anticoagulation.

28. What is the mechanism of action of Heparin?
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
Chronic anticoagulation.
Ceftriaxone
Heparin catalyzes the activation of antithrombin III.

29. What is the category of drug names ending in - caine (e.g. Lidocaine)
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels
Local anesthetic.
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
GI distress - Skin rash - and Seizures at high plasma levels

30. Which drug(s) cause this reaction: Neuro and Nephrotoxic?
- polymyxins
Beta -2 agonist.
Rapid (seconds)
-100% oxygen - hyperbaric

31. What neurotransmitter does Amantadine affect? How does it influence this NT?
These B-2 agonists cause respiratory smooth muscle to relax.
Penicillin - V
- Glucagon
Dopamine; causes its release from intact nerve terminals

32. List the mechanism - clinical use - & toxicity of Paclitaxel.
Modification via Acetylation
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.
- Nitrate - hydroxocobalamin thiosulfate
TMP- SMZ (DOC) - aerosolized pentamidine

33. What are three possible toxicities of NSAID usage?
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.)
Inhalational general anesthetic.
thick ascending limb
1. Renal damage 2. Aplastic anemia 3. GI distress

34. Describe first - order kinetics?
decrease the slope of phase 4 - increase PR interval (the AV node is particularly sensitive)
Ataxia - Dizziness - Slurred speech
Constant FRACTION eliminated per unit time.(exponential)
Neutropenia (ticlopidine); reserved for those who cannot tolerate aspirin.

35. What are common toxic side effects of Sulfonamides? (5)
- Hypersensitivity reactions - Hemolysis - Nephrotoxicity (tubulointerstitial nephritis) - Kernicterus in infants Displace other drugs from albumin (e.g. - warfarin)
It affects beta receptors equally and is used in AV heart block (rare).
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time
cholestyramine - colestipol

36. What is are two clinical uses of Cyclosporine?
Anaerobes
proarrhythmic
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.
Immediate anticoagulation for PE - stroke - angina - MI - DVT.

37. ________ ae not resistant to penicillinase - - but they are less susceptible than the other Beta lactams
Cephalosporins
AZT - to reduce risk of Fetal Transmission
Malaria (P. falciparum)
Edrophonium

38. What are two conditions in Which COX-2 inhibitors might be used?
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia
loop diuretics - spironolactone
narcolepsy - obesity - and attention deficit disorder (I wouldn't recommend this)
Rheumatoid and osteoarthritis.

39. What are two Glitazones?
Large anionic polymer - acidic
Gram + cocci - Haemophilus influenza - Enterobacter aerogenes - Neisseria species - P. mirabilis - E. coli - K. pneumoniae - Serratia marcescens ( HEN PEcKS )
1. Pioglitazone 2. Rosiglitazone.
Minor hepatotoxicity - Drug interactions (activates P450)

40. Which drug(s) cause this reaction: Cutaneous flushing (4)?
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.
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.
- Niacin - Ca++ channel blockers - adenosine - vancomycin

41. What is the mechanism of action of Mifepristone (RU486)?
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.
YES
Competitive inibitor of progestins at progesterone receptors.

42. What are the clinical indications for Azole therapy?
- Quinidine - quinine
Systemic mycoses
increase AP duration - increase ERP - increase QT interval - for use When other arrhythmics fail
Ceftriaxone

43. What are the side effects of Polymyxins?
Zidovudine (AZT) - Didanosine (ddI) - Zalcitabine (ddC) - Stavudine (d4T) - Lamivudine (3TC)
No - it inhibits the release of Nor Epi
Neurotoxicity - Acute renal tubular necrosis
For serious - Gram + multidrug - resistant organisms

44. Decrease Digitoxin dose in renal failure?
Clavulanic acid
BM suppression (neutropenia - anemia) - Peripheral neuropathy
Indirect agonist - uptake inhibitor
NO

45. What is the most common cause of Pt noncompliance with Macrolides?
TCA
Depolymerizes microtubules - impairing leukocyte chemotaxis and degranulation.
Potent immunosuppressive used in organ transplant recipients.
GI discomfort

46. How can Vancomycin - induced 'Red Man Syndrome' be prevented?
Digitoxin>95% Digoxin 75%
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.
Pretreat with antihistamines and a slow infusion rate
prevention of nodal arrhythmias (SVT)

47. Cautions When using Amiodarone?
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time
Gemfibrozil - Clofibrate
check PFTs - LFTs - and TFTs
fetal renal damage - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)

48. How is Rifampin used clinically?
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs
1. Antipyretic 2. Analgesic 3. Anti - inflammatory
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine

49. Which drug(s) cause this reaction: Stevens - Johnson syn. (3)?
Blastomyces - Coccidioides - Histoplasma - C. albicans; Hypercortisolism
- Ethosuxamide - sulfonamides - lamotrigine
Digitoxin>95% Digoxin 75%
Neurotoxicity - Acute renal tubular necrosis

50. Which drug(s) cause this reaction: Cough?
- ACE inhibitors (Losartan>no cough)
The only local anesthetic with vasoconstrictive properties.
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention
Amphotericin B - Nystatin - Fluconazole/azoles