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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. What is the mechanism of action of Clomiphene?
In treatment of malignant hyperthermia - due to concomitant use of halothane and succinylcholine. Also in neuroleptic malignant syndrome - a toxicity of antipsychotic drugs.
1. Skin rash 2. Agranulocytosis (rare) 3. Aplastic anemia
Norepinephrine
Clomiphene is a partial agonist at estrogen receptors in the pituitary gland. Prevents normal feedback inhibition and increses release of LH and FSHfrom the pituitary - Which stimulates ovulation.

2. What enzyme does Zileuton inhibit?
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.
Lipoxygenase
Blocks viral penetration/uncoating; may act to buffer the pH of the endosome

3. Which drug(s) cause this reaction: Atropine - like side effects?
- Nitrate - hydroxocobalamin thiosulfate
- Tricyclic antidepressants
Ceftriaxone
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic

4. Name common Polymyxins
- Ethanol - dialysis - & fomepizole
Nucleosides
Polymyxin B - Polymyxin E
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.

5. How does botulinum toxin result in respiratory arrest?
Inhibits cell wall mucopeptide formation - Bactericidal
Prevents the release of ACh - Which results in muscle paralysis.
- Cimetidine - ketoconazole - grapefruit juice - erythromycin - INH - sulfonamides
local anesthetic. CNS stimulation or depression. CV depression.

6. What are the clinical indications for Azole therapy?
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity
INH: Injures Neurons and Hepatocytes
Systemic mycoses
AmOxicillin has greater Oral bioavailability

7. Which individuals are predisposed to Sulfonamide - induced hemolysis?
Local anesthetic.
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).
- Tetracycline - amiodarone - sulfonamides
G6PD deficient individuals

8. Foscarnet does not require activation by a...
viral kinase
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).
not a sulfonamide - but action is the same as furosemide
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome

9. Steady state concentration is reached in __ number of half - lifes
Diarrhea
For serious - Gram + multidrug - resistant organisms
sedation - sleep alterations
In 4 half - lifes= (94%) T1/2 = (0.7x Vd)/CL

10. The MOA for Chloramphenicol is?
Prevents the release of ACh - Which results in muscle paralysis.
atropine - homatropine - tropicamide
dizziness - flushing - constipation (verapamil) - nausea
Inhibition of 50S peptidyl transferase - Bacteriostatic

11. List the specific antidote for this toxin: Arsenic (all heavy metals)
- Dimercaprol - succimer
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.
Chronic gout.
Bacitracin - Vancomycin

12. What is Imipenem always administered with?
Cilastatin
Pregnant women - Children; because animal studies show Damage to Cartilage
loop diuretics - spironolactone
Doxycycline - because it is fecally eliminated

13. What are toxic side effects for Metronidazole?
Disulfiram - like reaction with EtOH - Headache
Epinephrine
- Halothane - Valproic acid - acetaminophen - Amantia phalloides
Indomethacin is used to close a patent ductus arteriosus.

14. How does angiotensin II affect NE release?
It acts presynaptically to increase NE release.
Tricyclic antidepressant.
Ipratropium
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.

15. What are the Macrolides used for clinically?
With supplemental Folic Acid
- Upper respiratory tract infections - pneumonias - STDs: Gram+ cocci (streptococcal infect in pts allergic to penicillin) - Mycoplasma - Legionella - Chlamydia - Neisseria
Due to the presence of a bulkier R group
Ganciclovir is more toxic to host enzymes

16. What are the clinical uses for Imipenem/cilastatin?
Gram + cocci - Gram - rods - and Anerobes
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.
decrease
Pentavalent Antimony

17. Name the common Azoles
Fluconazole - Ketoconazole - Clotrimazole - Miconazole - Itraconazole
GI discomfort
No - warfarin - unlike heparin - can cross the placenta.
It acts presynaptically to increase NE release.

18. How does a competitive antagonist effect an agonist?
Hypersensitivity reactions
- Shifts the curve to the right - increases Km
- Niacin - Ca++ channel blockers - adenosine - vancomycin
Succinylcholine

19. ________ ae not resistant to penicillinase - - but they are less susceptible than the other Beta lactams
Norepinephrine (Alpha1 -2 and beta 1)
Cephalosporins
reversible SLE- like syndrome
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.

20. Amiodarone - toxicity?
Inhibits reabsorption of uric acid.
Bactericidal for: Gram + rod and cocci - Gram - cocci - and Spirochetes
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.

21. For Warfarin What is the Mechanism of action
Impairs the synthesis of vitamin K- dependent clotting factors
Pseudomembranous colitis (C. difficile) - fever - diarrhea
Penicillin - G
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow

22. Which RT inhibitor causes Megaloblastic Anemia?
GI side effects. (Indomethacin is less toxic - more commonly used.)
Carbachol - pilocarpine - physostigmine - echothiophate
AZT
- Cloazapine - carbamazapine - colchicine - PTU

23. What is an additional side effect of Methicillin?
Pseudomembranous colitis (C. difficile) - fever - diarrhea
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
Interstitial nephritis
- Shifts the curve to the right - increases Km

24. What conditions would you use dantrolene?
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.
Benzodiazepine.
In treatment of malignant hyperthermia - due to concomitant use of halothane and succinylcholine. Also in neuroleptic malignant syndrome - a toxicity of antipsychotic drugs.
- polymyxins

25. Antiarrhythmic Class III- effects?
increase AP duration - increase ERP - increase QT interval - for use When other arrhythmics fail
Bactericidal for: Gram + rod and cocci - Gram - cocci - and Spirochetes
TCA
proximal convoluted tubule

26. List the specific antidote for this toxin: Copper
- Penicillamine
Premature infants - because they lack UDP- glucuronyl transferase
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
Heparin catalyzes the activation of antithrombin III.

27. Adverse effects of Hydralazine?
Tricyclic antidepressant.
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention
scopolamine
Yes - it does not cross the placenta.

28. What is the category of drug names ending in - barbital (e.g. Phenobarbital)
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol
Pretreat with antihistamines and a slow infusion rate
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).
Babiturate.

29. What are the indications for using amphetamine?

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30. What is the definition of zero - order kinetics? Example?
torsade de pointes
- Constant AMOUNT eliminated per unit time. - Etoh & ASA
1. Taken daily 2. No protection against STDs 3. Raises triglycerides 4. Depression - weight gain - nausea - HTN 5. Hypercoagulable state
Fever/Chills - Hypotension - Nephrotoxicity - Arrhythmias

31. What are the major structural differences between Penicillin and Cephalosporin?
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)
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome
- ED 50 is less than the Km (less than 50% of receptors)
No - hemicholinum block the uptake of Choline and thus Ach synthesis

32. What is the mechanism of action of NSAIDs other than Aspirin?
- Alkalating agent - testicular - bladder - ovary -& lung - Nephrotoxicity & CN VIII damage.
- Lithium
sedation - positive Coombs' test
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.

33. Antimicrobial prophylaxis for Meningococcal infection
Fluconazole - Ketoconazole - Clotrimazole - Miconazole - Itraconazole
Modification via Acetylation
Rifampin (DOC) - minocycline
1)Binds penicillin - binding proteins 2) Blocks transpeptidase cross - linking of cell wall 3) Activates autolytic enzymes

34. Acetaminophen has What two clinical uses and lacks What one clinical use of the NSAIDs?
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.
anuria - CHF
Acetaminophen has antipyretic and analgesic properties - but lacks anti - inflammatory properties.
Ipratropium

35. Antiarrhythmic class IV- clinical use?
Triple sulfas or SMZ
- Ammonium Chloride
DOC in diagnosing and abolishing AV nodal arrhythmias
prevention of nodal arrhythmias (SVT)

36. How is Ribavirin used clinically?
all of them
distal convoluted tubule (early)
for RSV
Parkinson patients benefit from antimuscarinic agents through its inhibitory action within the indirect pathway.

37. What microorganisms are clinical indications for Tetracycline therapy?

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38. For Warfarin What is the Treatment for overdose
Digitoxin>95% Digoxin 75%
Malaria (P. falciparum)
is resistant
IV vitamin K and fresh frozen plasma

39. What do you treat Nematode/roundworm (pinworm - whipworm) infections with?
orthostatic and exercise hypotension - sexual dysfunction - diarrhea
No - hemicholinum block the uptake of Choline and thus Ach synthesis
Mebendazole/Thiabendazole - Pyrantel Pamoate
hypertrichosis - pericardial effusion - reflex tachycardia - angina - salt retention

40. Resistance mechanisms for Sulfonamides
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine
1. RNA pol inhibitor 2. Revs up P450 3. Red/orange body fluids 4. Rapid resistance if used alone

41. Antimicrobial prophylaxis for a history of recurrent UTIs
IV vitamin K and fresh frozen plasma
Modification via Acetylation
TMP- SMZ
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.

42. What two vasodilators require simultaneous treatment with beta blockers to prevent reflex tachycardia and diuretics to prevent salt retention?
hypertension - CHF - diabetic renal disease
Hydralazine and Minoxidil
With supplemental Folic Acid
Intrathecally

43. What is the mechanism of action of the glucocorticoids?
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.
decrease AP duration - affects ischemic or depolarized Purkinje and ventricular system
- Acetaldehyde - Nausea - vomiting - headache - & hypotension
Treatment of infertility.

44. Digoxin v. Digitoxin: excretion?
Digoxin=urinary Digitoxin=biliary
Malaria (P. falciparum)
Gram + cocci - Proteus mirabilis - E. coli - Klebsiella pneumoniae (PEcK)
Hypersensitivity reactions

45. MOA of Succinylcholine
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
Prevents the release of Ca from SR of skeletal muscle
blocks SR Ca2+ channels
CMV Retinitis in IC pts When Ganciclovir fails

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

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47. What is the MOA of Foscarnet?
Hypersensitivity reactions
Inhibits Viral DNA polymerase
Neomycin
H2 antagonist

48. Adverse effects of Loop Diuretics?
K+ wasting - metabolic alkalosis - hypotension - ototoxicity
Blocks Influenza A and RubellA; causes problems with the cerebellA
Those patients who are taking nitrates.
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.

49. What is the MOA for the Aminoglycosides?
Inhibits formation of Initiation Complex - causes misreading of mRNA - Bactericidal
impotence - exacerbation of asthma - CV effects - CNS effects - may mask hypoclycemia
As an anticholinesterase it increases endogenous ACh and thus increases strength.
all except the K+ sparing diuretics Spironolactone - Triamterene - Amiloride

50. What patients are at risk for life threatening hypotension When taking Sildenafil (Viagra)?
Those patients who are taking nitrates.
sedation - sleep alterations
SLUD (salivation - Lacrimation - urination - Defecation)as well as airway secretion - GI motility - acid secretions
1. Pioglitazone 2. Rosiglitazone.