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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. Antiarrhythmic class IA effects?
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.
SLUD (salivation - Lacrimation - urination - Defecation)as well as airway secretion - GI motility - acid secretions
Captopril - Enalapril - Lisinopril
Hypersensitivity reactions

2. How is Ribavirin used clinically?
Hormone synthesis inhibition (Gynecomastia) - Liver dysfunction (Inhibits CYP450) - Fever - Chills
for RSV
Neutropenia
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol

3. What is Nifurtimox administered for?

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4. What is combined with Ampicillin - Amoxicillin - Carbenicillin - Piperacillin - and Ticarcillin to enhance their spectrum?
In 4 half - lifes= (94%) T1/2 = (0.7x Vd)/CL
Carbenicillin - Piperacillin - and Ticarcillin
Lovastatin - Pravastatin - Simvastatin - Atorvastatin
Clavulanic acid

5. Quinidine - toxicity?
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval
Gram + cocci - Gram - rods - and Anerobes
Beta1 more than B2
1. Meningococcal carrier state 2. Chemoprophylaxis in contacts of children with H. influenzae type B

6. What is the main clinical use for the thrombolytics?
Treatment of infertility.
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.
Protease Inhibitors and Reverse Transcriptase Inhibitors
Early myocardial infarction.

7. What are common side effects of RT Inhibitors?
Gram - rods: Klebsiella species - Pseudomonas species - Serratia species
BM suppression (neutropenia - anemia) - Peripheral neuropathy
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.
Cephalosporins

8. What is action of insulin in the liver - in muscle - and in adipose tissue?
GI upset
Treatment of hypertension - especially with renal disease (lowers bp centrally - so flow is maintained to kidney).
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.
Scopolamine

9. Why does atropine dilate the pupil?
Heparin catalyzes the activation of antithrombin III.
Aluminum sucrose sulfate polymerizes in the acid environment of the stomach and selectively binds necrotic peptic ulcer tissue. Acts as a barrier to acid - pepsin - and bile.
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
Blocking muscarinic receptors in the circular fibers of the eye - results in unopposed action of radial muscles to dilate.

10. What enzyme is responsible for the production of Ach from Acetyl CoA and Choline
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.
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
compensatory tachycardia - fluid retention - lupus - like syndrome
Choline acetyltransferase

11. Antiarrhythmic class IV- clinical use?
prevention of nodal arrhythmias (SVT)
vasodilator - increases cGMP to induce smooth muscle relaxation (arterioles>veins; afterload reduction)
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
Diuresis in pateints with sulfa allergy

12. What is the MOA for the Macrolides?
Small lipid - soluble molecule
Acute gout.
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic
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.

13. List the mechanism - clinical use - & toxicity of Etoposide.
Chronic (weeks or months)
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.
It affects beta receptors equally and is used in AV heart block (rare).
- Vinca alkaloids(inhibit MT) - Paclitaxel

14. Explain differences between full and partial agonists(2).
- Act on same receptor - Full has greater efficacy
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)
thiazides - amiloride
With supplemental Folic Acid

15. What is the major side effect for Ampicillin and Amoxicillin?
Anaerobes
Hypersensitivity reactions
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.
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more

16. Beta Blockers - CNS toxicity?
Fever/Chills - Hypotension - Nephrotoxicity - Arrhythmias
hyperkalemia - endocrine effects (gynecomastia - anti - androgen)
sedation - sleep alterations
- Vitamin K & fresh frozen plasma

17. Adverse effects of Hydralazine?
Inhibit DNA Gyrase (topoisomerase II) - Bactericidal
Neostigmine - pyridostigmine edrophonium - physostigmine echothiophate
proximal convoluted tubule
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention

18. List the mechanism - clinical use - & toxicity of Vincristine.

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19. Will Hemicholinum affect the release of stored Ach during Cholinergic Stimulation
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol
No - hemicholinum block the uptake of Choline and thus Ach synthesis
Prevents the release of Ca from SR of skeletal muscle
- Niacin - Ca++ channel blockers - adenosine - vancomycin

20. List the specific antidote for this toxin: Acetaminophen
- N- acetylcystine
- Deferoxamine
Same as penicillin. Act as narrow spectrum antibiotics
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time

21. What are three toxicities of Leuprolied?
1. Antiandrogen 2. Nausea 3. Vomiting
cardiac muscle: Verapamil>Diltiazem>Nifedipine
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine

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

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23. What are the side effects of Polymyxins?
Neurotoxicity - Acute renal tubular necrosis
DOC in diagnosing and abolishing AV nodal arrhythmias
Aminoglycosides - Tetracyclines
decrease

24. For Warfarin What is the Structure
depresses ectopic pacemakers - especially in digoxin toxicity
Small lipid - soluble molecule
- S- phase anti - metabolite Pyr analogue - Colon - solid tumors - & BCC/ - Irreversible myelosuppression
Digoxin=urinary Digitoxin=biliary

25. Name some common Sulfonamides (4)
proximal convoluted tubule
Pseudomembranous colitis (C. difficile) - fever - diarrhea
Hemicholinium inhibits the transport of choline into the nerve - thus inhibiting formation of ACh.
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine

26. What is a common drug interaction associated with Griseofulvin?
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic
Increases coumadin metabolism
Rifampin (DOC) - minocycline
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions

27. What are two toxicities associated with Cyclosporine?
1. Predisposes to viral infections and lymphoma 2. Nephrotoxic (preventable with mannitol diuresis)
Sildenafil fills the penis
- Physostigmine salicylate
Chronic Hepatitis A and B - Kaposi's Sarcoma

28. Resistance mechanisms for Tetracycline
Decreased uptake or Increased transport out of cell
thiazides - amiloride
Nephrotoxicity
Ganciclovir is more toxic to host enzymes

29. Which drug(s) cause this reaction: SLE- like syndrome?
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis
Increases mean - systolic - and diastolic bp - while there is little change in pulse pressure.
- Hydralazine - Procainamide - INH - phenytoin
Well tolerated in general but occasionally - Nephrotoxicity - Ototoxicity - Thrombophlebitis - diffuse flushing='Red Man Syndrome'

30. What is the mechanism of action of Mifepristone (RU486)?
HTN - CHF - calcium stone formation - nephrogenic DI.
Competitive inibitor of progestins at progesterone receptors.
Acetaminophen has antipyretic and analgesic properties - but lacks anti - inflammatory properties.
- Quinidine - quinine

31. Antimicrobial prophylaxis for Gonorrhea
Ceftriaxone
loop diuretics - thiazides
Aluminum sucrose sulfate polymerizes in the acid environment of the stomach and selectively binds necrotic peptic ulcer tissue. Acts as a barrier to acid - pepsin - and bile.
glaucoma - urinary alkalinization - metabolic alkalosis - altitude sickness

32. Describe the MOA of Interferons (INF)
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis
Yes
GI upset

33. The MOA for Chloramphenicol is?
Decreased uptake or Increased transport out of cell
Inhibition of 50S peptidyl transferase - Bacteriostatic
Cell membrane Ca2+ channels of cardiac sarcomere
Forms toxic metabolites in the bacterial cell - Bactericidal

34. How do the Protease Inhibitors work?
Praziquantel
thick ascending limb
GnRH analog with agonist properties When used in pulsatile fashion and antagonist properties When used in continuous fashion - causing a transient initial burst of LH and FSH
Inhibt Assembly of new virus by Blocking Protease Enzyme

35. What is the category of drug names ending in - azine (e.g. Chlorpromazine)
Pregnant women - Children; because animal studies show Damage to Cartilage
Aminoglycosides
Small lipid - soluble molecule
Phenothiazine (neuroleptic - antiemetic).

36. Your patient wants an effective drug to treat his motion sickness - What would you prescribe
Suramin
- Penicillin
Scopolamine
Carbachol - pilocarpine - physostigmine - echothiophate

37. What drug is used to diagnose myasthenia gravis?
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.
edrophonium (extremely short acting anticholinesterase)
Gram + and Anerobes
They inhibit reuptake of NE at the nerve terminal (as does cocaine).

38. What is the loading dose formula?
Ld= (CpxVd)/F Cp=plasma conc. F= Bioaval.
Parkinson patients benefit from antimuscarinic agents through its inhibitory action within the indirect pathway.
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
Useful in muscle paralysis during surgery or mechanical ventilation.

39. How do we stop angina?
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time
severe hypertension - CHF
Carbachol - pilocarpine - physostigmine - echothiophate
- inhibits HGPRT (pur. Syn.) - Luk - Lymph

40. What is the mecanism of action - effective period - and ineffective period of use for Cromolyn in treating Asthma?
Aminoglycosides - Tetracyclines
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol
- acetylation - glucuron. - & sulfation - Conjugation - Polar product
Prevents release of mediators from mast cells. Effective only for the prophylaxis of asthma. Not effective during an acute attack.

41. Resistance mechanisms for Chloramphenicol
all of them
Modification via Acetylation
Prevents the release of calcium from the sarcoplasmic reticulum of skeletal muscle.
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.

42. Antiarrhythmic class IV- toxicity?
YES
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
hypertrichosis - pericardial effusion - reflex tachycardia - angina - salt retention
constipation - flushing - edema - CV effects (CHF - AV block - sinus node depression) - and torsade de pointes (Bepridil)

43. List the specific antidote for this toxin: Anticholinesterases (organophosphate.)
- Atropine & pralidoxime
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
Well tolerated in general but occasionally - Nephrotoxicity - Ototoxicity - Thrombophlebitis - diffuse flushing='Red Man Syndrome'
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.

44. What organism is Imipenem/cilastatin the Drug of Choice for?
- Quinidine - quinine
Abortifacient.
Enterobacter
- Halothane - Valproic acid - acetaminophen - Amantia phalloides

45. Spironolactone - mechanism?
Penicillin - Cephalosporins - Vancomycin - Aminoglycosides - Fluoroquinolones - Metronidazole
competitive inhibirot of aldosterone in the cortical collecting tubule
Meningitis (H. influenza - N. meningitidis - S. pneumoniae) - Conserative treatment due to toxicities
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.

46. For Heparin What is the Site of action
Blood
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.
Beta lactams - inhibit cell wall synthesis - Bactericidal
Short.

47. In What population does Gray Baby Syndrome occur? Why?
Aminoglycosides
vascular sm. Mus.: Nifedipine>Diltiazem>Verapamil
It inhibits release of NE.
Premature infants - because they lack UDP- glucuronyl transferase

48. Which drug(s) cause this reaction: P450 inhibition(6)?
decrease the slope of phase 4 - increase PR interval (the AV node is particularly sensitive)
- Cimetidine - ketoconazole - grapefruit juice - erythromycin - INH - sulfonamides
Beta Blockers
Acetaminophen has antipyretic and analgesic properties - but lacks anti - inflammatory properties.

49. What is the MOA for Methicillin - Nafcillin - and Dicloxacillin?
Same as penicillin. Act as narrow spectrum antibiotics
Prevents the release of Ca from SR of skeletal muscle
1. Taken daily 2. No protection against STDs 3. Raises triglycerides 4. Depression - weight gain - nausea - HTN 5. Hypercoagulable state
edrophonium (extremely short acting anticholinesterase)

50. How is Foscarnet used clinically?
CMV Retinitis in IC pts When Ganciclovir fails
Irreversibly inhibits H+/K+ ATPase in stomach parietal cells.
Long.
Inhibit Ergosterol synthesis