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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. Which diuretics cause alkalosis?
loop diuretics - thiazides
first dose orthostatic hypotension - dizziness - headache
Botulinum
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.

2. What are two indirect acting adrenergic agonists?
amphetamine and ephedrine
- Fluoroquinolones
Beta - lactamase cleavage of Beta - lactam ring
- Phenytoin

3. Ibutilide - toxicity?
Methylation of rRNA near Erythromycin's ribosome binding site
torsade de pointes
Hypersensitivity reactions
Aplastic anemia (dose independent) - Gray Baby Syndrome

4. What are the clinical uses for Ticlopidine - Clopidogrel?
Choline acetyltransferase
Decreases synthesis of Mycolic Acid
Oral
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.

5. What are five possible toxic effects of Aspirin therapy?

6. What are the clinical uses for Imipenem/cilastatin?
Gram + cocci - Gram - rods - and Anerobes
Abortifacient.
Oral treatment of superficial infections
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.

7. Explain pH dependent urinary drug elimination?
- Ammonium Chloride
Amphotericin B - Nystatin - Fluconazole/azoles
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more
post MI and digitalis induced arrhythmias

8. Why is pyridostigmine effective in the treatment of myasthenia gravis?
As an anticholinesterase it increases endogenous ACh and thus increases strength.
Pituitary hormone.
sedation - sleep alterations
- Ammonium Chloride

9. What cholinomimetics might your pt be taking for his glaucoma
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia
Activates cholinergic receptors on bladder and bowel smooth muscle - alleviating post - op and neurogenic ileus and urinary retention.
Carbachol - pilocarpine - physostigmine - echothiophate
blocks SR Ca2+ channels

10. Adverse effects of beta - blockers?
- Hydralazine - Procainamide - INH - phenytoin
impotence - asthma - CV effects (bradycardia - CHF - AV block) - CNS effects (sedation - sleep alterations)
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more
Inhibit Ergosterol synthesis

11. What is the category - method of use - and adverse effects of Salmeterol in Asthma treatment?
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis
Beta Blockers
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.
anticholinesterase glaucoma

12. Antiarrhythmic class IB- clinical uses?
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.
Epinephrine to treat anaphylaxis. Also useful if you have open angle glaucoma - asthma - or hypotension.
Minor hepatotoxicity - Drug interactions (activates P450)
post MI and digitalis induced arrhythmias

13. What is the MOA of Ganciclovir?
- Lithium
Inhibits CMV DNA polymerase
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids
Ganciclovir is more toxic to host enzymes

14. How do spare receptors effect the Km?
Same as penicillin. Extended spectrum antibiotics
- ED 50 is less than the Km (less than 50% of receptors)
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval
physostigmine

15. Reserpine will block the syntheis of this drug and but not its precursor.
Bleeding.
Pentamidine
Blocks Norepi - but not Dopamine
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia

16. Mg+- clinical use?
Short.
- Acetaldehyde - Nausea - vomiting - headache - & hypotension
Nitrates
effective in torsade de pointes and digoxin toxicity

17. What are three possible complications of Heparin therapy?
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions
Indirect agonist - uptake inhibitor
Acetylcholine esterase
Zidovudine (AZT) - Didanosine (ddI) - Zalcitabine (ddC) - Stavudine (d4T) - Lamivudine (3TC)

18. What is the MOA for the Tetracyclines?
amphetamine and ephedrine
Tricyclic antidepressant.
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic

19. List the specific antidote for this toxin: Antimuscarinic (anticholinergic)
torsade de pointes - excessive Beta block
- Lithium
- Physostigmine salicylate
Prevention of NSAID- induced peptic ulcers - maintains a PDA.

20. Describe Phase I metabolism in liver(3)?
- reduction - oxy - & hydrolysis - H2O sol. Polar product - P450
It inhibits release of NE.
troponin - tropomyosin system
1. Gastric ulceration 2. Bleeding 3. Hyperventilation 4. Reye's syndrome 5. Tinnitus (CN VIII)

21. What is the category of drug names ending in - ane (e.g. Halothane)
Neurotoxicity - Acute renal tubular necrosis
Inhalational general anesthetic.
dizziness - flushing - constipation (verapamil) - nausea
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)

22. MOA of Succinylcholine
torsade de pointes
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome
Prevents the release of Ca from SR of skeletal muscle
- Hypersensitivity reactions - Hemolysis - Nephrotoxicity (tubulointerstitial nephritis) - Kernicterus in infants Displace other drugs from albumin (e.g. - warfarin)

23. For Warfarin What is the Onset of action
Slow - limited by half lives of clotting factors
Hypersensitivity reactions
- N- acetylcystine
Extended spectrum penicillin: certain Gram + bacteria and Gram - rods

24. ________ ae not resistant to penicillinase - - but they are less susceptible than the other Beta lactams
Cephalosporins
Carbenicillin - Piperacillin - and Ticarcillin
cross - allergenic
Prefers beta's at low doses - but at higher doses alpha agonist effects are predominantly seen.

25. What are five advantages of Oral Contraceptives (synthetic progestins - estrogen)?
- Tricyclic antidepressants
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
Buy AT 30 - CELL at 50'
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic

26. What is the MOA for Vancomycin?
Treatment of hypertension - especially with renal disease (lowers bp centrally - so flow is maintained to kidney).
Inhibits cell wall mucopeptide formation - Bactericidal
1) Hypersensitivity reactions 2) Increased nephrotoxicity of Aminoglycosides 3) Disulfiram - like reaction with ethanol (those with a methylthiotetrazole group - e.g. - cefamandole)
distal convoluted tubule (early)

27. What is used to reverse the action of Heparin?
1. Antipyretic 2. Analgesic 3. Anti - inflammatory
Clavulanic acid
Protamine Sulfate is used for rapid reversal of heparinization (positively charged molecule that binds to negatively charged heparin).
Epinephrine to treat anaphylaxis. Also useful if you have open angle glaucoma - asthma - or hypotension.

28. A fellow passenger on a Carnival cruise ship looks pale and diaphoretic - What antimuscarinic agent would you give them?
- Shifts the curve to the right - increases Km
scopolamine
distal convoluted tubule (early)
is resistant

29. What is Clindamycin used for clinically?
Anaerobic infections (e.g. - B. fragilis - C. perfringens)
cholestyramine - colestipol
Ld= (CpxVd)/F Cp=plasma conc. F= Bioaval.
For serious - Gram + multidrug - resistant organisms

30. What are the indications for using amphetamine?

31. What drug is used to treat Trematode/fluke (e.g. - Schistosomes - Paragonimus - Clonorchis) or Cysticercosis
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.
Aminoglycosides
Praziquantel
Pyridoxine (B6) administration

32. Which drug(s) cause this reaction: Agranulocytosis (3)?
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)
- Cloazapine - carbamazapine - colchicine - PTU
- Acetaldehyde - Nausea - vomiting - headache - & hypotension
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome

33. Resistance mechanisms for Macrolides

34. For Heparin What is the Route of administration
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.
is resistant
Paranteral (IV - SC)
collecting ducts

35. What populations are Floroquinolones contraindicated in? Why?
Pregnant women - Children; because animal studies show Damage to Cartilage
- aminoglycosides - loop diuretics - cisplatin
Beta Blockers
Yes - it does not cross the placenta.

36. What are the major toxic side effects of the Cephalosporins?
hyperkalemia - endocrine effects (gynecomastia - anti - androgen)
cortical collecting tubule
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention
1) Hypersensitivity reactions 2) Increased nephrotoxicity of Aminoglycosides 3) Disulfiram - like reaction with ethanol (those with a methylthiotetrazole group - e.g. - cefamandole)

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

38. What is the category of drug names ending in - oxin (e.g. Digoxin)
Cardiac glycoside (inotropic agent).
Oral treatment of superficial infections
Liver
Acetylcholinesterase; ACh is broken down into choline and acetate.

39. Which drug(s) cause this reaction: P450 induction(6)?
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine
hypokalemia - slight hyperlipidemia - hyperuricemia - lassitude - hypercalcemia - hyperglycemia
Gram + - Gram - - Norcardia - Chlamydia
Verapamil - Diltiazem - Bepridil

40. Which receptors does phenylephrine act upon?
Ciprofloxacin - Norfloxacin - Ofloxacin - Grepafloxacin - Enoxacin - Nalidixic acid
- Chloramphenicol
alpha -1 > alpha -2; used as a pupil dilator - vasoconstrictor - and for nasal decongestion
hyperkalemia - endocrine effects (gynecomastia - anti - androgen)

41. MOA: Disrupt bacterial/fungal cell membranes
Prevents the release of ACh - Which results in muscle paralysis.
Polymyxins
- Protamine
Flecainide - Encainide - Propafenone

42. What is the mechanism of action of NSAIDs other than Aspirin?
- Clindamycin
Imipenem
Binds to the Pyrophosphate Binding Site of the enzyme
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.

43. Toxic effects of TMP include?
Well tolerated in general but occasionally - Nephrotoxicity - Ototoxicity - Thrombophlebitis - diffuse flushing='Red Man Syndrome'
DOC in diagnosing and abolishing AV nodal arrhythmias
blocks SR Ca2+ channels
Megaloblastic anemia - Leukopenia - Granulocytopenia

44. What is the mechanism of Azathioprine?
Antimetabolite derivative of 6- mercaptopurine that interferes with the metablolism and synthesis of nucleic acid.
Bismuth and Amoxicillin or Tetracycline; against Helobacter pylori
Tricyclic antidepressant.
Buy AT 30 - CELL at 50'

45. Secretion of What drug is inhibited by Probenacid used to treat chronic gout?
Penicillin.
Rifampin
Gentamicin - Neomycin - Amikacin - Tobramycin - Streptomycin
- Class III antiarrhythmics (sotalol) - class IA (quinidine)

46. How are Interferons (INF) used clinically?

47. What type of neurological blockade would hexamethonium create?
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic
Useful in muscle paralysis during surgery or mechanical ventilation.
Hexamethonium is a nicotinic antagonist - and thus is a ganglionic blocker.
- NaHCO3

48. What is the memory key for the effect of magnesium hydroxide overuse?
- Aminocaproic acid
Mg = Must go to the bathroom.
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol
Can affect absorption - bioavailability - or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying.

49. What are four clinical activities of Aspirin?
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis
Staphlococcus aureus
1. Antipyretic 2. Analgesic 3. Anti - inflammatory 4. Antiplatelet drug.
decrease the slope of phase 4 - increase PR interval (the AV node is particularly sensitive)

50. Antimicrobial prophylaxis for a history of recurrent UTIs
GI upset - Superinfections - Skin rashes - Headache - Dizziness
Zidovudine (AZT) - Didanosine (ddI) - Zalcitabine (ddC) - Stavudine (d4T) - Lamivudine (3TC)
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.
TMP- SMZ