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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. Antiarrhythmic class IV- clinical use?
prevention of nodal arrhythmias (SVT)
Chronic anticoagulation.
post MI and digitalis induced arrhythmias
Protamine sulfate

2. What is the clincial use for Misoprostol?
Irreversibly inhibits H+/K+ ATPase in stomach parietal cells.
Prevention of NSAID- induced peptic ulcers - maintains a PDA.
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic
Epinephirine(Alpha1 -2 and Beta 1 -2)

3. What are are the Sulfonylureas (general description) and What is their use?
Prevention of NSAID- induced peptic ulcers - maintains a PDA.
Constant FRACTION eliminated per unit time.(exponential)
Diarrhea
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).

4. What are the four conditions in Which Omeprazole - Lansoprazole is used?
- Tricyclic antidepressants
Oral treatment of superficial infections
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome
AV nodal cells

5. Which RT inhibitors cause Lactic Acidosis?
Sucralfate cannot work in the presence of antacids or H2 blockers because it requires an acidic environment to polymerize.
Nucleosides
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.
Prefers beta's at low doses - but at higher doses alpha agonist effects are predominantly seen.

6. List the specific antidote for this toxin: Acetaminophen
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia
hypertension - CHF - diabetic renal disease
- EDTA - dimercaprol - succimer - & penicillamine
- N- acetylcystine

7. What is the MOA of Isoniazid (INH)?
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.
NO
Pregnant women - Children; because animal studies show Damage to Cartilage
Decreases synthesis of Mycolic Acid

8. What is the memory key for organisms treated with Tetracyclines?

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9. What is the category of drug names ending in - azine (e.g. Chlorpromazine)
Phenothiazine (neuroleptic - antiemetic).
AV nodal cells
Decreases synthesis of Mycolic Acid
Receptors = D1=D2>beta>alpha - thus increasing heart rate (beta) and blood pressure (alpha vasoconstriction) while maintaining kidney perfusion (dopamine receptors)

10. Name two classes of drugs for HIV therapy
Protease Inhibitors and Reverse Transcriptase Inhibitors
Hemolytic anemia
blocks SR Ca2+ channels
Blocks Norepi - but not Dopamine

11. Adverse effects of beta - blockers?
Yes - it does not cross the placenta.
cross - allergenic
impotence - asthma - CV effects (bradycardia - CHF - AV block) - CNS effects (sedation - sleep alterations)
Pentavalent Antimony

12. What are two toxicities of the Glitazones?
1. Skin rash 2. Agranulocytosis (rare) 3. Aplastic anemia
- Daunorubicin & Doxorubicin
Hemolytic anemia
1. Weight gain 2. Hepatotoxicity (troglitazone)

13. MOA: Disrupt bacterial/fungal cell membranes
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors
Polymyxins
- Quinidine - quinine
Neostigmine - pyridostigmine edrophonium - physostigmine echothiophate

14. What is the major side effect for Carbenicillin - Piperacillin - and Ticarcillin?
Hypersensitivity reactions
Prevents the release of Ca from SR of skeletal muscle
Prevention of NSAID- induced peptic ulcers - maintains a PDA.
Oral

15. Which of these three drugs will cause a reflex bradycardia in your pt (Norepi - Epi - or Isoporterenol)
Same as penicillin. Extended spectrum antibiotics
Chronic gout.
DOC in diagnosing and abolishing AV nodal arrhythmias
Norepinephrine

16. Which individuals are predisposed to Sulfonamide - induced hemolysis?
Finasteride inhibits 5 Alpha - reductase - this decreases the conversion of testosterone to dihydrotestosterone - useful in BPH
Abortifacient.
1. Predisposes to viral infections and lymphoma 2. Nephrotoxic (preventable with mannitol diuresis)
G6PD deficient individuals

17. Ca2+ channel blockers - mechanism?
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility
Flutamide is a nonsteroidal competitive inhibitor of androgens at the testosterone receptor - used in prostate carcinoma.
Used in combination therapy with SMZ to sequentially block folate 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)

18. Which diuretics decrease urine Ca2+?
1. Acarbose 2. Miglitol
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
thiazides - amiloride
1) Chloramphenical = bacteriostatic 2) Erythromycin = bacteriostatic 3) Lincomycin = bacteriostatic 4)cLindamycin = bacteriostatic

19. What is a possible toxicity of Ticlopidine - Clopidogrel usage?
- A57Blue lines in gingiva & long bones - Encephalopathy & Foot drop - Abdominal colic / - Sideroblastic anemia
- Clindamycin
Neutropenia (ticlopidine); reserved for those who cannot tolerate aspirin.
Acetaminophen has antipyretic and analgesic properties - but lacks anti - inflammatory properties.

20. What are signs of Sildenafil (Viagra) toxicity?
Headache - flushing - dyspepsia - blue - green color vision.
severe hypertension - CHF
Rifampin (DOC) - minocycline
1. Phospholipase A2 is prevented from releasing arachidonic acid 2. Decreases protein synthesis thus lowering amount of Cyclooxygenase enzymes

21. Resistance mechanisms for Cephalosporins/Penicillins
Large anionic polymer - acidic
Beta - lactamase cleavage of Beta - lactam ring
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
Diarrhea

22. Do Tetracyclines penetrate the CNS?
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis
1. Weight gain 2. Hepatotoxicity (troglitazone)
Only in limited amounts

23. What is the category of drug names ending in - tidine (e.g. Cimetidine)
blocks SR Ca2+ channels
Edrophonium
H2 antagonist
Carbenicillin - Piperacillin - and Ticarcillin

24. For Heparin What is the Ability to inhibit coagulation in vitro
Yes
hypertension - angina - arrhythmias
Onchocerciasis ('river blindness'-- rIVER- mectin)
Nitrates

25. What sympathomimetic would you not prescribe for hypotension in a pt with renal artery sclerosis.
Blood
Inhibit RT of HIV and prevent the incorporation of viral genome into the host DNA
Norepinephrine (Alpha1 -2 and beta 1)
- Tetracycline

26. What is the category - desired effect - and period of use of albuterol in the treatment of Asthma?
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
Digoxin=urinary Digitoxin=biliary
Beta 2 agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Use during acute exacerbation.
Blocking muscarinic receptors in the circular fibers of the eye - results in unopposed action of radial muscles to dilate.

27. What is the memory key for Metronidazole's clinical uses?
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.
GET on the Metro
GI disturbances.
Peptic ulcer disease.

28. What are common side effects of RT Inhibitors?
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
- Daunorubicin & Doxorubicin
BM suppression (neutropenia - anemia) - Peripheral neuropathy
- Ethanol - dialysis - & fomepizole

29. Mg+- clinical use?
Prevents the release of Ca from SR of skeletal muscle
Pentavalent Antimony
Chronic Hepatitis A and B - Kaposi's Sarcoma
effective in torsade de pointes and digoxin toxicity

30. What is combined with Ampicillin - Amoxicillin - Carbenicillin - Piperacillin - and Ticarcillin to enhance their spectrum?
Penicillin - G
Clavulanic acid
Ataxia - Dizziness - Slurred speech
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).

31. What is the clinical use for Nystatin?
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic
AluMINIMUM amount of feces.
Topical and Oral - for Oral Candidiasis (Thrush)
Anaerobic infections (e.g. - B. fragilis - C. perfringens)

32. Why would you give a drug like pancuronium or succinylcholine?
Useful in muscle paralysis during surgery or mechanical ventilation.
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs
Flutamide is a nonsteroidal competitive inhibitor of androgens at the testosterone receptor - used in prostate carcinoma.
Diarrhea - Urination - Miosis - Bronchospasm - Bradycardia - Excitation of skeletal muscle and CNS - Lacrimation - Sweating - and Salivation = DUMBBELS; also abdominal cramping

33. List the mechanism - clinical use - & toxicity of Nitrosureas.
- Alkalate DNA - Brain tumors - CNS toxicity
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.
K+ wasting - metabolic alkalosis - hypotension - ototoxicity
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.

34. What is the MOA for Vancomycin?
Disulfiram - like reaction with EtOH - Headache
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome
Inhibits cell wall mucopeptide formation - Bactericidal
- Tamoxifen

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

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36. What enzymes are inhibited by NSAIDs - acetaminophen and COX II inhibitors?
The PT.
Fast vs. Slow Acetylators
Cyclooxygenases (COX I - COX II).
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia

37. Acetazolamide causes?

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38. List the mechanism - clinical use - & toxicity of Methotrexate.
Pentamidine
Vd= (Amt. of drug in body/ Plasma drug conc.)
Cephalosporins
- S- phase anti - metabolite folate analogue - Luk - Lymp - sarc - RA - & psoriasis / - Reversible myelosuppression

39. What are the major structural differences between Penicillin and Cephalosporin?
- partial agonist can have increased - decreased - /A21or equal potency as full agonist. - Potency is an independent factor.
- aminoglycosides - loop diuretics - cisplatin
- Vitamin K & fresh frozen plasma
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)

40. What is the memory key for Isoniazid (INH) toxicity?
Polymyxins
Hypersensitivity reactions
INH: Injures Neurons and Hepatocytes
Edrophonium

41. For Warfarin What is the Mechanism of action
all of them
Impairs the synthesis of vitamin K- dependent clotting factors
1. Better bioavailability 2. 2 to 4 times longer half life 3. Can be administered subcutaneously 4. Does not require laboratory monitoring
Corticosteroids; prevent production of leukotrienes from arachodonic acid by blocking phospholipase A2. Drugs of choice in a patient with status asthmaticus (in combination with albuterol.)

42. What are the side effects of Rifampin?
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).
Stimulates beta adrenergic receptors
Vibrio cholerae Acne Chlamydia Ureaplasma Urealyticum Mycoplasma pneumoniae Borrelia burgdorferi (Lyme's) Rickettsia Tularemia
Minor hepatotoxicity - Drug interactions (activates P450)

43. Which drug(s) cause this reaction: Pulmonary fibrosis(3)?
Activates cholinergic receptors on bladder and bowel smooth muscle - alleviating post - op and neurogenic ileus and urinary retention.
- Bleomycin - amiodarone - busulfan
Lidocaine - Mexiletine - Tocainide
TMP- SMZ (DOC) - aerosolized pentamidine

44. Adverse effects of Loop Diuretics?
K+ wasting - metabolic alkalosis - hypotension - ototoxicity
Hypokalemic metabolic alkalosis - hyponatremia - hyperGlycemia - hyperLipidemia - hyperUricemia - hyperCalcemia - sulfa allergy.
Leukotrienes increasing bronchial tone.
Inhibits Viral DNA polymerase

45. How would you reverse the effect of a neuromuscular blocking agent?
Give an antichloinesterase - neostigmine - edrophonium - etc
ACE inhibitor.
Digitoxin>95% Digoxin 75%
Local anesthetic.

46. List the mechanism - clinical use - & toxicity of Etoposide.
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.
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).
Polymyxins
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.

47. Why are the Sulfonylureas inactive in IDDM (type -1)?
GI disturbances.
Bethanechol - Neostigmine - physostigmine
Because they require some residual islet function.
Norepinephrine

48. What microorganisms is Aztreonam not effective against?
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
Gram + and Anerobes
- Methylene blue
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine

49. List the mechanism - clinical use - & toxicity of Paclitaxel.
Diuresis in pateints with sulfa allergy
- Glucagon
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.
Ipratropium

50. What is action of insulin in the liver - in muscle - and in adipose tissue?
impotence - exacerbation of asthma - CV effects - CNS effects - may mask hypoclycemia
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.
Corticosteroids; prevent production of leukotrienes from arachodonic acid by blocking phospholipase A2. Drugs of choice in a patient with status asthmaticus (in combination with albuterol.)
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.