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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. List the mechanism - clinical use - & toxicity of Tamoxifen.
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.
1) Hypersensitivity reactions 2) Increased nephrotoxicity of Aminoglycosides 3) Disulfiram - like reaction with ethanol (those with a methylthiotetrazole group - e.g. - cefamandole)
- Ammonium Chloride
- Estrogen receptor antagonist - Breast CA - increased endometrial CA risk

2. What are two processes Corticosteroids inhibit leading to decreased inflammation?
Bethanechol - Neostigmine - physostigmine
It affects beta receptors equally and is used in AV heart block (rare).
1. Phospholipase A2 is prevented from releasing arachidonic acid 2. Decreases protein synthesis thus lowering amount of Cyclooxygenase enzymes
Long.

3. Acetaldehyde is metabolized by Acetaldehyde dehydrogenase - Which drug inhibs this enzyme?
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
- Disulfram & also sulfonylureas - metronidazole
Gram + cocci - Proteus mirabilis - E. coli - Klebsiella pneumoniae (PEcK)
penicillinase resistant

4. What is used to reverse the action of Heparin?
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic
The only local anesthetic with vasoconstrictive properties.
Protamine Sulfate is used for rapid reversal of heparinization (positively charged molecule that binds to negatively charged heparin).

5. How does resistance to Vancomycin occur?
With an amino acid change of D- ala D- ala to D- ala D- lac
Systemic mycoses
- ED 50 is less than the Km (less than 50% of receptors)
Methylation of rRNA near Erythromycin's ribosome binding site

6. What is the MOA of Ribavirin?
Inhibits DNA dependent RNA polymerase
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis
Malaria (P. falciparum)
Gram + cocci - Haemophilus influenza - Enterobacter aerogenes - Neisseria species - P. mirabilis - E. coli - K. pneumoniae - Serratia marcescens ( HEN PEcKS )

7. What enzyme is responsible for the breakdown of ACh in the synaptic cleft?
TMP- SMZ (DOC) - aerosolized pentamidine
anuria - CHF
Acetylcholinesterase; ACh is broken down into choline and acetate.
- Physostigmine salicylate

8. Why would dopamine be useful in treating shock?
Rifampin - Ethambutol - Streptomycin - Pyrazinamide - Isoniazid (INH)
- Vitamin K & fresh frozen plasma
Receptors = D1=D2>beta>alpha - thus increasing heart rate (beta) and blood pressure (alpha vasoconstriction) while maintaining kidney perfusion (dopamine receptors)
Same as penicillin. Extended spectrum antibiotics

9. What is the memory aid for subunit distribution of ribosomal inhibitors?

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10. Mannitol - contraindications?
Disulfiram - like reaction with EtOH - Headache
Constant FRACTION eliminated per unit time.(exponential)
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity
anuria - CHF

11. What is the formula for Volume of distribution (Vd)
Yes - it does not cross the placenta.
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.
Vd= (Amt. of drug in body/ Plasma drug conc.)
- Alkalating agents+cisplatin - Doxorubicin+Dactinomycin - Bleomycin - Etoposide

12. Where does Griseofulvin deposit?
- Triggers apoptosis - CLL - Hodgkin's in MOPP - Cushing - like syndrome
IV vitamin K and fresh frozen plasma
Keratin containing tissues - e.g. - nails
Doxycycline - because it is fecally eliminated

13. What is the category - desired effect - and period of use of albuterol in the treatment of Asthma?
Beta 2 agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Use during acute exacerbation.
Delirium - Tremor - Nephrotoxicity
1. Gastric ulceration 2. Bleeding 3. Hyperventilation 4. Reye's syndrome 5. Tinnitus (CN VIII)
Overdose produces hepatic necrosis; acetaminophen metablolite depletes glutathione and forms toxic tissue adducts in liver.

14. What is the mechanism of action of Ticlopidine - Clopidogrel
Nephrotoxicity (esp. with Cephalosporins) - Ototoxicity (esp. with Loop Diuretics)
- Hypersensitivity reactions - Hemolysis - Nephrotoxicity (tubulointerstitial nephritis) - Kernicterus in infants Displace other drugs from albumin (e.g. - warfarin)
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.

15. List some specifics of lead poisoning(4)?
1. Pioglitazone 2. Rosiglitazone.
- A57Blue lines in gingiva & long bones - Encephalopathy & Foot drop - Abdominal colic / - Sideroblastic anemia
narcolepsy - obesity - and attention deficit disorder (I wouldn't recommend this)
- Ammonium Chloride

16. What is the MOA of Isoniazid (INH)?
Decreases synthesis of Mycolic Acid
torsade de pointes
- Methotrexate - 5 FU - 6 mercaptopurine
- Chloramphenicol

17. What are the products and their toxicities of the metabolism of ethanol by / alcohol dehydrogenase?
- Acetaldehyde - Nausea - vomiting - headache - & hypotension
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).
Long.

18. Which drug(s) cause this reaction: G6PD hemolysis(8)?
Digoxin=urinary Digitoxin=biliary
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol
Competitive inibitor of progestins at progesterone receptors.
Anaerobes

19. Name four Antiarrhythmic drugs in class III.
Hexamethonium is a nicotinic antagonist - and thus is a ganglionic blocker.
Sotalol - Ibutilide - Bretylium - Amiodarone
Scopolamine
not a sulfonamide - but action is the same as furosemide

20. What is the MOA for the Cephalosporins?
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
Beta lactams - inhibit cell wall synthesis - Bactericidal
Blocks Norepi - but not Dopamine
Heparin catalyzes the activation of antithrombin III.

21. For Warfarin What is the Treatment for overdose
Tricyclic antidepressant.
Beta antagonist.
IV vitamin K and fresh frozen plasma
Similar to cyclosporine; binds to FK- binding protein - inhibiting secretion of IL-2 and other cytokines.

22. What parasites are treated with Pyrantel Pamoate (more specific)?
1. Hypoglycemia (more common with 2nd - generation drugs: glyburide - glipizide) 2. Disulfiram - like effects (not seen with 2nd - generation drugs).
Sotalol - Ibutilide - Bretylium - Amiodarone
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
Tendonitis and Tendon rupture

23. What is the mechanism of action of Mifepristone (RU486)?
Competitive inibitor of progestins at progesterone receptors.
CMV Retinitis in IC pts When Ganciclovir fails
Erythromycin - Azithromycin - Clarithromycin
Carbenicillin - Piperacillin - and Ticarcillin

24. What is the category of drug names ending in - navir (e.g. Saquinavir)
- Oral Contraceptives
1. Pioglitazone 2. Rosiglitazone.
Polymyxin B - Polymyxin E
Protease inhibitor.

25. What is a prerequisite for Acyclovir activation?
Hypersensitivity reactions
1. Addison's disease 2. Inflammation 3. Immune suppression 4. Asthma
It must be Phosphorylated by Viral Thymidine Kinase
- inhibits HGPRT (pur. Syn.) - Luk - Lymph

26. What is the mecanism of action - effective period - and ineffective period of use for Cromolyn in treating Asthma?
Inhibit Ergosterol synthesis
Prevents release of mediators from mast cells. Effective only for the prophylaxis of asthma. Not effective during an acute attack.
Verapamil - Diltiazem - Bepridil
Long.

27. List the mechanism - clinical use - & toxicity of Cyclophosphamide.
Hormone synthesis inhibition (Gynecomastia) - Liver dysfunction (Inhibits CYP450) - Fever - Chills
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.
- Alkalates DNA - CML - Pulmonary fibrosis hyperpigmentation
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.

28. What are four conditions in Which H2 Blockers are used clinically?
1. Meningococcal carrier state 2. Chemoprophylaxis in contacts of children with H. influenzae type B
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome

29. Which diuretics increase urine NaCl?
Chronic (weeks or months)
No
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions
all of them

30. What is the difference between the affinity for beta receptors between albuterol/terbutaline and dantroline?
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol
cholestyramine - colestipol
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.
1. Better bioavailability 2. 2 to 4 times longer half life 3. Can be administered subcutaneously 4. Does not require laboratory monitoring

31. What is the category and mechanism of action of Zafirlukast in Asthma treatment?
GI disturbances.
Norepinephrine
Antileukotriene; blocks leukotriene receptors.
- Antipsychotics

32. ___________ are Teratogenic
Clavulanic acid
Antimetabolite derivative of 6- mercaptopurine that interferes with the metablolism and synthesis of nucleic acid.
- Triggers apoptosis - CLL - Hodgkin's in MOPP - Cushing - like syndrome
Aminoglycosides

33. How does a competitive antagonist effect an agonist?
Flecainide - Encainide - Propafenone
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia
When pts have Low CD4+ (< 500 cells/cubic mm) or a High Viral Load
- Shifts the curve to the right - increases Km

34. What are two indirect acting adrenergic agonists?
Neutropenia
cyanide toxicity (releases CN)
Tricyclic antidepressant.
amphetamine and ephedrine

35. How do we stop angina?
Gram + cocci - Haemophilus influenza - Enterobacter aerogenes - Neisseria species - P. mirabilis - E. coli - K. pneumoniae - Serratia marcescens ( HEN PEcKS )
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time
Increase target cell response to insulin.
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome

36. Name two bile acid resins.
cholestyramine - colestipol
- MT polymerization inhibitor(M phase) - MOPP - lymphoma - Willm's & choriocarcinoma - neurotoxicity and myelosuppression
Yes
It affects beta receptors equally and is used in AV heart block (rare).

37. What are four advantages of newer low - molecular - weight heparins (Enoxaparin)?
It acts presynaptically to increase NE release.
Hypersensitivity reactions
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.
1. Better bioavailability 2. 2 to 4 times longer half life 3. Can be administered subcutaneously 4. Does not require laboratory monitoring

38. For Warfarin What is the Structure
Used in combination therapy with SMZ to sequentially block folate synthesis
Small lipid - soluble molecule
Fever/Chills - Hypotension - Nephrotoxicity - Arrhythmias
Inhibit viral DNA polymerase

39. ________ ae not resistant to penicillinase - - but they are less susceptible than the other Beta lactams
Cephalosporins
Succinylcholine
Inhibits Viral DNA polymerase
DOC in diagnosing and abolishing AV nodal arrhythmias

40. What is the mechanism of action of Acetaminophen?
Overdose produces hepatic necrosis; acetaminophen metablolite depletes glutathione and forms toxic tissue adducts in liver.
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.
Erythromycin - Azithromycin - Clarithromycin
anticholinesterase glaucoma

41. Which drug(s) cause this reaction: Tubulointerstitial Nephritis (5)?
Digitoxin 70% Digoxin 20-40%
Beta lactams - inhibit cell wall synthesis - Bactericidal
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)

42. Antiarrhythmic class IV- clinical use?
It inhibits release of NE.
prevention of nodal arrhythmias (SVT)
Ipratropium
1. Buffalo hump 2. Moon facies 3. Truncal obesity 4. Muscle wasting 5. Thin skin 6. Easy bruisability 7. Osteoporosis 8. Adrenocortical atrophy 9. Peptic ulcers

43. Antiarrhythmic class IB- toxicity?
for RSV
Butyrophenone (neuroleptic).
Flecainide - Encainide - Propafenone
local anesthetic. CNS stimulation or depression. CV depression.

44. What is the mechanism of action of the Alpha - glucosidase inhibitors?
Beta - lactam antibiotics
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.
It must be Phosphorylated by Viral Thymidine Kinase
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.

45. Dobutamine used for the tx of shock acts on Which receptors
impotence - asthma - CV effects (bradycardia - CHF - AV block) - CNS effects (sedation - sleep alterations)
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.
Beta1 more than B2
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors

46. What are the major structural differences between Penicillin and Cephalosporin?
sedation - depression - nasal stuffiness - diarrhea
Chronic gout.
- Clindamycin
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)

47. What are the clinical uses for 2nd Generation Cephalosporins?
Gram + cocci - Haemophilus influenza - Enterobacter aerogenes - Neisseria species - P. mirabilis - E. coli - K. pneumoniae - Serratia marcescens ( HEN PEcKS )
RESPIre
decrease the slope of phase 4 - increase PR interval (the AV node is particularly sensitive)
Succinylcholine

48. What is the category - method of use - and adverse effects of Salmeterol in Asthma treatment?
Local anesthetic.
- NaHCO3
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.
Increases mean - systolic - and diastolic bp - while there is little change in pulse pressure.

49. For Warfarin What is the Route of administration
Oral
Cilastatin
Inhibits DNA dependent RNA polymerase
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.

50. Ca2+ channel blockers - clinical use?
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids
hypertension - angina - arrhythmias
AZT
Bleeding.