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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 are two processes Corticosteroids inhibit leading to decreased inflammation?
1. Phospholipase A2 is prevented from releasing arachidonic acid 2. Decreases protein synthesis thus lowering amount of Cyclooxygenase enzymes
- Penicillin
Due to the presence of a bulkier R group
anticholinesterase glaucoma

2. List the specific antidote for this toxin: Cyanide
- Nitrate - hydroxocobalamin thiosulfate
Polymyxins
Blocks Norepi - but not Dopamine
It acts presynaptically to increase NE release.

3. K+- clinical use?
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
depresses ectopic pacemakers - especially in digoxin toxicity
Activates antithrombin III
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.

4. What is a Ribavirin toxicity?
No
Hemolytic anemia
Ciprofloxacin - Norfloxacin - Ofloxacin - Grepafloxacin - Enoxacin - Nalidixic acid
Neurotoxicity - Acute renal tubular necrosis

5. Is toxicity rare or common whith Cromolyn used in Asthma prevention?
Nifedipine - Verapamil - Diltiazem
Triple sulfas or SMZ
Rare.
GI side effects. (Indomethacin is less toxic - more commonly used.)

6. List the mechanism - clinical use - & toxicity of 5 FU.
- S- phase anti - metabolite Pyr analogue - Colon - solid tumors - & BCC/ - Irreversible myelosuppression
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain
Cell membrane Ca2+ channels of cardiac sarcomere
- Disulfram & also sulfonylureas - metronidazole

7. List the specific antidote for this toxin: Beta Blockers
- Glucagon
Warfarin interferes with the normal synthesis and gamma - carboxylation of vitamin K- dependent clotting factors II - VII - IX - and X - Protein C and S via vitamin K antagonism.
Sulfonamides - Trimethoprim
Reversible block of histamine H2 receptors

8. Ethacrynic Acid - clinical use?
Giardiasis - Amoebic dysentery (E. histolytica) - Bacterial vaginitis (Gardnerella vaginalis) - Trichomonas
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval
Diuresis in pateints with sulfa allergy
competitive inhibirot of aldosterone in the cortical collecting tubule

9. Antiarrhythmic class II- effects?
Warfarin interferes with the normal synthesis and gamma - carboxylation of vitamin K- dependent clotting factors II - VII - IX - and X - Protein C and S via vitamin K antagonism.
decrease the slope of phase 4 - increase PR interval (the AV node is particularly sensitive)
Modification via Acetylation
Nitrates

10. What are three clinical uses of the Leuprolide?
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids
- Glucocorticoid withdrawal
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.
The PT.

11. What is the MOA for the Cephalosporins?
Beta lactams - inhibit cell wall synthesis - Bactericidal
In treatment of malignant hyperthermia - due to concomitant use of halothane and succinylcholine. Also in neuroleptic malignant syndrome - a toxicity of antipsychotic drugs.
ACIDazolamide' causes acidosis
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)

12. What are the products and their toxicities of the metabolism of ethanol by / alcohol dehydrogenase?
GI disturbances.
- Alkalate DNA - Brain tumors - CNS toxicity
Penicillin.
- Acetaldehyde - Nausea - vomiting - headache - & hypotension

13. A 12yo patient was treated for a reaction to a bee sting - What drug provides the best coverage of sympathomimetic receptors?
- Vinca alkaloids(inhibit MT) - Paclitaxel
Epinephirine(Alpha1 -2 and Beta 1 -2)
Cell membrane Ca2+ channels of cardiac sarcomere
Saquinavir - Ritonavir - Indinavir - Nelfinavir

14. What is the clinical use for Ampicillin and Amoxicillin?
Pituitary hormone.
Extended spectrum penicillin: certain Gram + bacteria and Gram - rods
Gemfibrozil - Clofibrate
Digitoxin 168hrs Digoxin 40 hrs

15. Which drug(s) cause this reaction: Stevens - Johnson syn. (3)?
- Ethosuxamide - sulfonamides - lamotrigine
Finasteride inhibits 5 Alpha - reductase - this decreases the conversion of testosterone to dihydrotestosterone - useful in BPH
Verapamil - Diltiazem - Bepridil
With an amino acid change of D- ala D- ala to D- ala D- lac

16. In What population does Gray Baby Syndrome occur? Why?
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more
Premature infants - because they lack UDP- glucuronyl transferase
- Glucagon
depresses ectopic pacemakers - especially in digoxin toxicity

17. What is the category of drug names ending in - caine (e.g. Lidocaine)
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs
Acetaminophen has antipyretic and analgesic properties - but lacks anti - inflammatory properties.
Local anesthetic.

18. List the specific antidote for this toxin: Iron
- Alkalate DNA - Brain tumors - CNS toxicity
- Deferoxamine
Sotalol - Ibutilide - Bretylium - Amiodarone
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.

19. Mannitol - site of action?
cholestyramine - colestipol
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.
proximal convoluted tubule - thin descending limb - and collecting duct
Beta 2 agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Use during acute exacerbation.

20. ACE inhibitors - mechanism?
- inhibits HGPRT (pur. Syn.) - Luk - Lymph
check PFTs - LFTs - and TFTs
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased

21. List the specific antidote for this toxin: Antimuscarinic (anticholinergic)
- Oral Contraceptives
- Physostigmine salicylate
Does not cross
CL= (rate of elimination of drug/ Plasma drug conc.)

22. How are Sulfonamides employed clinically?
Gram + - Gram - - Norcardia - Chlamydia
1. Antiandrogen 2. Nausea 3. Vomiting
prevention of nodal arrhythmias (SVT)
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone

23. Cocaine casues vasoconstriction and local anesthesia by What mechanism
Ipratropium
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.)
Antileukotriene; blocks leukotriene receptors.
Indirect agonist - uptake inhibitor

24. For Warfarin What is the Treatment for overdose
Neostigmine - pyridostigmine edrophonium - physostigmine echothiophate
NO HYPERURICEMIA - NO SULFA AllERGY; same as furosemide otherwise
Captopril - Enalapril - Lisinopril
IV vitamin K and fresh frozen plasma

25. What is the clincial use for Misoprostol?
Prevention of NSAID- induced peptic ulcers - maintains a PDA.
Short.
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.

26. Guanethidine enhances the release of Norepi?
No - it inhibits the release of Nor Epi
- Methylene blue
Cryptococcal meningitis in AIDS patients and Candidal infections of all types
- Cloazapine - carbamazapine - colchicine - PTU

27. Digitalis - site of action?
- Ammonium Chloride
- Phenytoin
Na/K ATPase
Rifampin (DOC) - minocycline

28. What are five toxicities associated with Tacrolimus (FK506)?
Pralidoxime regenerates active cholinesterase.
GI discomfort - Acute cholestatic hepatitis - Eosinophilia - Skin rashes
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.
blocking the beta adrenergic receptor leads to decreased cAMP - and decreased Ca2+ flux

29. What conditions would you use dantrolene?
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia
In treatment of malignant hyperthermia - due to concomitant use of halothane and succinylcholine. Also in neuroleptic malignant syndrome - a toxicity of antipsychotic drugs.
decrease
Yes - it does not cross the placenta.

30. List the specific antidote for this toxin: Methanol & Ethylene glycol
- Glucocorticoid withdrawal
- Ethanol - dialysis - & fomepizole
Prefers beta's at low doses - but at higher doses alpha agonist effects are predominantly seen.
- Alkalate DNA - Brain tumors - CNS toxicity

31. For Heparin What is the Ability to inhibit coagulation in vitro
anuria - CHF
Yes
Large anionic polymer - acidic
Chronic gout.

32. MOA: Block protein synthesis at 50s subunit
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
Digoxin=urinary Digitoxin=biliary
- Metronidazole - certain cephalosporins - procarbazine - sulfonylureas
atropine - homatropine - tropicamide

33. The MOA for Chloramphenicol is?
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia
alpha -1 > alpha -2; used as a pupil dilator - vasoconstrictor - and for nasal decongestion
Inhibition of 50S peptidyl transferase - Bacteriostatic
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)

34. What is the clinical use for Sildenafil (Viagra)?
Erectile dysfunction.
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
Prophylaxis for Influenza A - Rubella; Parkinson's disease
GI side effects. (Indomethacin is less toxic - more commonly used.)

35. What is a possible result of overdose of Acetaminophen?
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain
Overdose produces hepatic necrosis; acetaminophen metablolite depletes glutathione and forms toxic tissue adducts in liver.
It acts presynaptically to increase NE release.

36. MOA: Disrupt fungal cell membranes
Penicillin - Ampicillin - Ticarcillin - Pipercillin - Imipenem - Aztreonam - Cephalosporins
1)Binds penicillin - binding proteins 2) Blocks transpeptidase cross - linking of cell wall 3) Activates autolytic enzymes
Amphotericin B - Nystatin - Fluconazole/azoles
Modification via Acetylation - Adenylation - or Phosphorylation

37. What is the mechanism of action of Probenacid used to treat chronic gout?
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors
Inhibits reabsorption of uric acid.
bradycardia - AV block - CHF
- Aminocaproic acid

38. What are three toxicities of Propylthiouracil?
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.
1. Skin rash 2. Agranulocytosis (rare) 3. Aplastic anemia
glaucoma - urinary alkalinization - metabolic alkalosis - altitude sickness
Those patients who are taking nitrates.

39. MOA: Bactericidal antibiotics
- Shifts the curve down - reduces Vmax
reversible SLE- like syndrome
blocking the beta adrenergic receptor leads to decreased cAMP - and decreased Ca2+ flux
Penicillin - Cephalosporins - Vancomycin - Aminoglycosides - Fluoroquinolones - Metronidazole

40. Verapamil has similar action to?
Beta Blockers
Penicillin - V
As an anticholinesterase it increases endogenous ACh and thus increases strength.
Protamine sulfate

41. Antiarrhythmic class IA effects?
Phenothiazine (neuroleptic - antiemetic).
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.
Norepinephrine (Alpha1 -2 and beta 1)
Keratin containing tissues - e.g. - nails

42. Why is reserpine effective in treating HTN?
Inhibits bacterial Dihydrofolate Reductase - Bacteriostatic
Staphlococcus aureus and Clostridium difficile (pseudomembranous colitis)
Reserpine inhibits dopamine transport into vesicles - attenuating its conversion to NE by dopamine beta - hydroxylase.
Pseudomonas species and Gram - rods

43. Which drug(s) cause this reaction: Drug induced Parkinson's (4) ?
- Tetracycline
- Haloperidol - chlorpromazine - reserpine - MPTP
Constant FRACTION eliminated per unit time.(exponential)
- Alkalinize urine & dialysis

44. Which drug(s) cause this reaction: SLE- like syndrome?
Vibrio cholerae Acne Chlamydia Ureaplasma Urealyticum Mycoplasma pneumoniae Borrelia burgdorferi (Lyme's) Rickettsia Tularemia
- Hydralazine - Procainamide - INH - phenytoin
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine
Hexamethonium is a nicotinic antagonist - and thus is a ganglionic blocker.

45. Hydralazine - toxicity?
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.
1. Reliable (<1% failure) 2. Lowers risk of endometrial and ovarian cancer 3. Decreased incidence of ectopic pregnancy 4. Lower risk of pelvic infections 5. Regulation of menses
- Formaldehyde & formic acid - severe acidosis & retinal damage
compensatory tachycardia - fluid retention - lupus - like syndrome

46. What is the clinical utility of clonidine?
GI side effects. (Indomethacin is less toxic - more commonly used.)
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.
Captopril - Enalapril - Lisinopril
Treatment of hypertension - especially with renal disease (lowers bp centrally - so flow is maintained to kidney).

47. What is the most common cause of Pt noncompliance with Macrolides?
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval
GI discomfort
- A57Blue lines in gingiva & long bones - Encephalopathy & Foot drop - Abdominal colic / - Sideroblastic anemia
effective in torsade de pointes and digoxin toxicity

48. Adverse effects of ganglionic blockers?
- S- phase anti - metabolite folate analogue - Luk - Lymp - sarc - RA - & psoriasis / - Reversible myelosuppression
Same as penicillin. Act as narrow spectrum antibiotics
severe orthostatic hypotension - blurred vision - constipation - sexual dysfunction
Similar to cyclosporine; binds to FK- binding protein - inhibiting secretion of IL-2 and other cytokines.

49. What is Metronidazole used for clinically?
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium
Neutropenia (ticlopidine); reserved for those who cannot tolerate aspirin.
- Flumazenil
first dose orthostatic hypotension - dizziness - headache

50. What two vasodilators require simultaneous treatment with beta blockers to prevent reflex tachycardia and diuretics to prevent salt retention?
Hydralazine and Minoxidil
Cyclooxygenases (COX I - COX II).
Used in combination therapy with SMZ to sequentially block folate synthesis
1. Better bioavailability 2. 2 to 4 times longer half life 3. Can be administered subcutaneously 4. Does not require laboratory monitoring