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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.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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. What are the major toxic side effects of Imipenem/cilastatin?
GI distress - Skin rash - and Seizures at high plasma levels
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility
Sildenafil fills the penis
Penicillin - Ampicillin - Ticarcillin - Pipercillin - Imipenem - Aztreonam - Cephalosporins

2. Why is Cilastatin administered with Imipenem?
To inhibit renal Dihydropeptidase I and decrease Imipenem inactivation in the renal tubules
- Methotrexate - 5 FU - 6 mercaptopurine
- Isoniazid
Zidovudine (AZT) - Didanosine (ddI) - Zalcitabine (ddC) - Stavudine (d4T) - Lamivudine (3TC)

3. What are three types of antacids and the problems that can result from their overuse?
Beta - lactam antibiotics
vascular sm. Mus.: Nifedipine>Diltiazem>Verapamil
Gram + - Gram - - Norcardia - Chlamydia
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia

4. What is the enzyme inhibited - the effect of this inhibition - and the clinical use of the antiandrogren Finasteride?
Gram + cocci - Haemophilus influenza - Enterobacter aerogenes - Neisseria species - P. mirabilis - E. coli - K. pneumoniae - Serratia marcescens ( HEN PEcKS )
Does not cross
- Ethanol - dialysis - & fomepizole
Finasteride inhibits 5 Alpha - reductase - this decreases the conversion of testosterone to dihydrotestosterone - useful in BPH

5. Adverse effects of Captopril?
Prophylaxis for Influenza A - Rubella; Parkinson's disease
Can affect absorption - bioavailability - or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying.
ACIDazolamide' causes acidosis
fetal renal toxicity - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)

6. Adverse effects of Minoxidil?
hypertrichosis - pericardial effusion - reflex tachycardia - angina - salt retention
Ataxia - Dizziness - Slurred speech
Resistant Gram - infections
Beta adrenergic receptors and Ca2+ channels (stimulatory)

7. Name the common Nucleoside Reverse Transcriptase Inhibitors
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.
Rare.
Zidovudine (AZT) - Didanosine (ddI) - Zalcitabine (ddC) - Stavudine (d4T) - Lamivudine (3TC)
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids

8. What are three complications of Warfarin usage?
Cilastatin
aPTT (intrinsic pathway)
1. Bleeding 2. Teratogenicity 3. Drug - drug interactions
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.

9. How does botulinum toxin result in respiratory arrest?
Prevents the release of ACh - Which results in muscle paralysis.
Pregnant women - Children; because animal studies show Damage to Cartilage
Acts as a wide spectrum carbapenem
Acetylcholinesterase; ACh is broken down into choline and acetate.

10. Secretion of What drug is inhibited by Probenacid used to treat chronic gout?
Inhibits bacterial Dihydrofolate Reductase - Bacteriostatic
1. Gastric ulceration 2. Bleeding 3. Hyperventilation 4. Reye's syndrome 5. Tinnitus (CN VIII)
Cephalosporins
Penicillin.

11. What sympathomimetic would you not prescribe for hypotension in a pt with renal artery sclerosis.
Norepinephrine (Alpha1 -2 and beta 1)
Tricyclic antidepressant.
- Alkalinize urine & dialysis
reversible SLE- like syndrome

12. List the mechanism - clinical use - & toxicity of Methotrexate.
Neutropenia (ticlopidine); reserved for those who cannot tolerate aspirin.
- S- phase anti - metabolite folate analogue - Luk - Lymp - sarc - RA - & psoriasis / - Reversible myelosuppression
Antimetabolite derivative of 6- mercaptopurine that interferes with the metablolism and synthesis of nucleic acid.
1. Addison's disease 2. Inflammation 3. Immune suppression 4. Asthma

13. What is the mechanism of action of Probenacid used to treat chronic gout?
NO AP duration effect. useful in V- tach that progresses to V- fib and in intractable SVT Last RESORT
severe orthostatic hypotension - blurred vision - constipation - sexual dysfunction
Inhibits reabsorption of uric acid.
Pseudomonas species and Gram - rods

14. How does dantrolene work?
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors
Aminoglycosides - Tetracyclines
Prevents the release of calcium from the sarcoplasmic reticulum of skeletal muscle.
Disulfiram - like reaction with EtOH - Headache

15. Which cancer drugs work at the level of mRNA(2)?
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic
decrease
- Steroids - Tamoxifen
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors

16. Resistance mechanisms for Cephalosporins/Penicillins
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine
Beta - lactamase cleavage of Beta - lactam ring
Mg = Must go to the bathroom.
Flutamide is a nonsteroidal competitive inhibitor of androgens at the testosterone receptor - used in prostate carcinoma.

17. What is the most common cause of Pt noncompliance with Macrolides?
GI discomfort
1)Binds penicillin - binding proteins 2) Blocks transpeptidase cross - linking of cell wall 3) Activates autolytic enzymes
Ipratropium
Extended spectrum penicillin: certain Gram + bacteria and Gram - rods

18. List the specific antidote for this toxin: TPA & Streptokinase
- Aminocaproic acid
Carbenicillin - Piperacillin - and Ticarcillin
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased
- Act on same receptor - Full has greater efficacy

19. Resistance mechanisms for Tetracycline
1. Skin rash 2. Agranulocytosis (rare) 3. Aplastic anemia
DHPG (dihydroxy-2- propoxymethyl guanine)
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens
Decreased uptake or Increased transport out of cell

20. Digoxin v. Digitoxin: protein binding?
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.
Heparin catalyzes the activation of antithrombin III.
Digitoxin 70% Digoxin 20-40%
Hypersensitivity reactions

21. What is Clindamycin used for clinically?
Anaerobic infections (e.g. - B. fragilis - C. perfringens)
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.
- Constant AMOUNT eliminated per unit time. - Etoh & ASA
Imipenem

22. What physiological effects was the Anes using Atropine to tx
Albuterol - tertbutaline
- Acetaldehyde - Nausea - vomiting - headache - & hypotension
hypertension - angina - arrhythmias
SLUD (salivation - Lacrimation - urination - Defecation)as well as airway secretion - GI motility - acid secretions

23. What microorganisms are Aminoglycosides ineffective against?
Megaloblastic anemia - Leukopenia - Granulocytopenia
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone
Anaerobes
Muscarinic antagonist; competatively blocks muscarinic receptors - preventing bronchoconstriction.

24. Which drug(s) cause this reaction: Torsade de pointes (2)?
- Class III antiarrhythmics (sotalol) - class IA (quinidine)
- Act on same receptor - Full has greater efficacy
Inhibits bacterial Dihydrofolate Reductase - Bacteriostatic
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia

25. Which antimicrobials inhibit protein synthesis at the 50S subunit? (4)
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)
1) Chloramphenical = bacteriostatic 2) Erythromycin = bacteriostatic 3) Lincomycin = bacteriostatic 4)cLindamycin = bacteriostatic
Minor hepatotoxicity - Drug interactions (activates P450)
Beta 2 agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Use during acute exacerbation.

26. List the specific antidote for this toxin: Copper
- Penicillamine
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic
Aplastic anemia (dose independent) - Gray Baby Syndrome
Does not cross

27. Antimicrobial prophylaxis for Meningococcal infection
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
NO AP duration effect. useful in V- tach that progresses to V- fib and in intractable SVT Last RESORT
Rifampin (DOC) - minocycline
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.

28. What is the category and mechanism of action of Zileuton in Asthma treatment?
Antileukotriene; blocks synthesis by lipoxygenase.
Pentamidine
- Oral Contraceptives
pulmonary edema - dehydration

29. List five common glucocorticoids.
- Flumazenil
Digoxin=urinary Digitoxin=biliary
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone
Succinylcholine

30. Antiarrhythmic class IA effects?
hyperaldosteronism - K+ depletion - CHF
Acetaminophen has antipyretic and analgesic properties - but lacks anti - inflammatory properties.
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.
hyperkalemia - endocrine effects (gynecomastia - anti - androgen)

31. Acetazolamide - site of action?
Prevents the release of Ca from SR of skeletal muscle
proximal convoluted tubule
Prevention of NSAID- induced peptic ulcers - maintains a PDA.
thiazides - amiloride

32. Mannitol - site of action?
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
Norepinephrine
proximal convoluted tubule - thin descending limb - and collecting duct
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia

33. Describe Phase II metabolism in liver(3)?
Penicillin - Ampicillin - Ticarcillin - Pipercillin - Imipenem - Aztreonam - Cephalosporins
- acetylation - glucuron. - & sulfation - Conjugation - Polar product
proximal convoluted tubule - thin descending limb - and collecting duct
- Ethosuxamide - sulfonamides - lamotrigine

34. What are the phases of succinylcholine neuromuscular blockade?
Norepinephrine
Beta - lactamase cleavage of Beta - lactam ring
Blastomyces - Coccidioides - Histoplasma - C. albicans; Hypercortisolism
Phase 1 = prolonged depolarization - no antidote - effect potentiated by anticholinesterase; Phase 2 = repolarized but blocked - an anticholinesterase is the antidote for this phase.

35. Why would dopamine be useful in treating shock?
Receptors = D1=D2>beta>alpha - thus increasing heart rate (beta) and blood pressure (alpha vasoconstriction) while maintaining kidney perfusion (dopamine receptors)
GET on the Metro
- Chloramphenicol
Antileukotriene; blocks leukotriene receptors.

36. What is the mechanism of action of the H2 Blockers?
Activates cholinergic receptors on bladder and bowel smooth muscle - alleviating post - op and neurogenic ileus and urinary retention.
1. RNA pol inhibitor 2. Revs up P450 3. Red/orange body fluids 4. Rapid resistance if used alone
Reversible block of histamine H2 receptors
Ciprofloxacin - Norfloxacin - Ofloxacin - Grepafloxacin - Enoxacin - Nalidixic acid

37. What patients are at risk for life threatening hypotension When taking Sildenafil (Viagra)?
cortical collecting tubule
Those patients who are taking nitrates.
torsade de pointes
Non - Nucleosides

38. Name five Antiarrhythmic drugs in class II?
Cimetidine is a potent inhibitor of P450; it also has an antiandrogenic effect and decreases renal excretion of creatinine. Other H2 blockers are relatively free of these effects.
propanolol - esmolol - metoprolol - atenolol - timolol
GI disturbances.
Foscarnet = pyroFosphate analog

39. What is the clinical use for Clomiphene?
Triple Therapy' 2 Nucleoside RT Inhibitors with a Protease Inhibitor
Treatment of infertility.
Tubocurarine - atracurium - mivacurium - pancuronium - vecuronium - rapacuronium
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow

40. How does NE modulate its own release? What other neurotransmitter has this same effect?
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.
Liver
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone

41. What cholinergic inhibitor acts by directly inhibiting Ach release at the presynaptic terminal
AZT - to reduce risk of Fetal Transmission
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
PT
Botulinum

42. Specifically - How does Foscarnet inhibit viral DNA pol?
carbonic anhydrase inhibitors - K+ sparing diuretics
Binds to the Pyrophosphate Binding Site of the enzyme
Blocking muscarinic receptors in the circular fibers of the eye - results in unopposed action of radial muscles to dilate.
Erythromycin - Azithromycin - Clarithromycin

43. What is the MOA for Clindamycin?
- Atropine & pralidoxime
Foscarnet = pyroFosphate analog
Blocks Peptide Bond formation at the 50S subunit - Bacteriostatic
1. Phospholipase A2 is prevented from releasing arachidonic acid 2. Decreases protein synthesis thus lowering amount of Cyclooxygenase enzymes

44. How does a competitive antagonist effect an agonist?
- Shifts the curve to the right - increases Km
Acute (hours)
decrease AP duration - affects ischemic or depolarized Purkinje and ventricular system
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.

45. What do Aminoglycosides require for uptake?
Oxygen
Neomycin
Methicillin - Nafcillin - and Dicloxacillin
For serious - Gram + multidrug - resistant organisms

46. How is Griseofulvin used clinically?
Oral treatment of superficial infections
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
With an amino acid change of D- ala D- ala to D- ala D- lac
Misoprostol is contraindicated in women of childbearing potential because it is an abortifacient.

47. What is the receptor affinity and clinical use of isoproterenol?
Inhibits formation of Initiation Complex - causes misreading of mRNA - Bactericidal
It affects beta receptors equally and is used in AV heart block (rare).
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide
Intrathecally

48. Which drug increases Sys BP w/o affecting Pulse Pressure
Epinephrine
Forms toxic metabolites in the bacterial cell - Bactericidal
dizziness - flushing - constipation (verapamil) - nausea
dry mouth - sedation - severe rebound hypertension

49. What is the category of drug names ending in - azol (e.g. Ketoconazole)
Albuterol - tertbutaline
1) Chloramphenical = bacteriostatic 2) Erythromycin = bacteriostatic 3) Lincomycin = bacteriostatic 4)cLindamycin = bacteriostatic
anuria - CHF
Antifungal.

50. Describe the MOA of Interferons (INF)
Similar to cyclosporine; binds to FK- binding protein - inhibiting secretion of IL-2 and other cytokines.
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis
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)
- Acetaldehyde - Nausea - vomiting - headache - & hypotension