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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 is the MOA of Ribavirin?
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide
- Dimercaprol - succimer
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis
DOC in diagnosing and abolishing AV nodal arrhythmias

2. What enzyme is responsible for the production of Ach from Acetyl CoA and Choline
Prevents the release of ACh - Which results in muscle paralysis.
Choline acetyltransferase
Inhibits CMV DNA polymerase
Rapid (seconds)

3. Does Warfarin have a long - medium - or short half life?
Inhibits cell wall mucopeptide formation - Bactericidal
Small lipid - soluble molecule
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions
Long.

4. What are Aminoglycosides used for clinically?
Cilastatin
Resistant Gram - infections
Severe Gram - rod infections.
Protease Inhibitors and Reverse Transcriptase Inhibitors

5. What cholinergic inhibitor acts by directly inhibiting Ach release at the presynaptic terminal
Botulinum
VACUUM your Bed Room'
amphetamine and ephedrine
new arrhythmias - hypotension

6. What is Nifurtimox administered for?

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7. What is the main clinical use for the thrombolytics?
Quinolones
Protamine Sulfate is used for rapid reversal of heparinization (positively charged molecule that binds to negatively charged heparin).
Early myocardial infarction.
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention

8. What is the category of drug names ending in - zosin (e.g. Prazosin)
Same as penicillin. Extended spectrum antibiotics
Alpha -1 antagonist
Primaquine
As an anticholinesterase it increases endogenous ACh and thus increases strength.

9. When is HIV therapy initiated?
Does not cross
1) Chloramphenical = bacteriostatic 2) Erythromycin = bacteriostatic 3) Lincomycin = bacteriostatic 4)cLindamycin = bacteriostatic
impotence - asthma - CV effects (bradycardia - CHF - AV block) - CNS effects (sedation - sleep alterations)
When pts have Low CD4+ (< 500 cells/cubic mm) or a High Viral Load

10. What is the mechanism of action of Aspirin?
Pseudomonas species and Gram - rods
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.

11. What is the category of drug names ending in - azepam (e.g. Diazepam)
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time
Benzodiazepine.
GI upset
Hypersensitivity reactions

12. Dobutamine used for the tx of shock acts on Which receptors
Beta1 more than B2
Due to the presence of a bulkier R group
impotence - exacerbation of asthma - CV effects - CNS effects - may mask hypoclycemia
- Flumazenil

13. What is a common side effect of Colchicine used to treat acute gout - especially When given orally?
GI disturbances.
all of them
GI side effects. (Indomethacin is less toxic - more commonly used.)
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.

14. What are common toxicities associated with Tetracyclines?

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15. What is the memory key for the effect of aluminum hydroxide overuse?
AluMINIMUM amount of feces.
Stimulates beta adrenergic receptors
Penicillin - V
Beta adrenergic receptors and Ca2+ channels (stimulatory)

16. What microorganisms are clinical indications for Tetracycline therapy?

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17. What is the mechanism of action and clinical use of the antiandrogen Flutamide?
- Daunorubicin & Doxorubicin
Flutamide is a nonsteroidal competitive inhibitor of androgens at the testosterone receptor - used in prostate carcinoma.
1. Phospholipase A2 is prevented from releasing arachidonic acid 2. Decreases protein synthesis thus lowering amount of Cyclooxygenase enzymes
Edrophonium

18. What is the MOA for Nystatin?
Binds ergosterol - Disrupts fungal membranes
1. Phospholipase A2 is prevented from releasing arachidonic acid 2. Decreases protein synthesis thus lowering amount of Cyclooxygenase enzymes
Blocks viral penetration/uncoating; may act to buffer the pH of the endosome
Pretreat with antihistamines and a slow infusion rate

19. Cocaine shares is mechanism of action with What antidepressant
They inhibit reuptake of NE at the nerve terminal (as does cocaine).
Pretreat with antihistamines and a slow infusion rate
Intrathecally
TCA

20. Which diuretics increase urine NaCl?
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis
Inhibits DNA dependent RNA polymerase
all of them
Gram + cocci - Proteus mirabilis - E. coli - Klebsiella pneumoniae (PEcK)

21. List the mechanism - clinical use - & toxicity of Cyclophosphamide.
The PTT.
- Tamoxifen
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.
1. Phospholipase A2 is prevented from releasing arachidonic acid 2. Decreases protein synthesis thus lowering amount of Cyclooxygenase enzymes

22. K+ sparing diuretics - site of action?
Epinephrine
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents
1. Taken daily 2. No protection against STDs 3. Raises triglycerides 4. Depression - weight gain - nausea - HTN 5. Hypercoagulable state
cortical collecting tubule

23. As an Anes you want to use a depolarizing neuromuscular blocking drug on your pt - What do you use
Only in limited amounts
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.
Succinylcholine
Indomethacin is used to close a patent ductus arteriosus.

24. Are Ampicillin and Amoxicillin are not...
penicillinase resistant
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.
Nitrates
Ototoxicity - Hypokalemia - Dehydration - Allergy (sulfa) - Nephritis (interstitial) - Gout

25. What is the MOA for the Cephalosporins?
Impairs the synthesis of vitamin K- dependent clotting factors
aPTT (intrinsic pathway)
Nephrotoxicity
Beta lactams - inhibit cell wall synthesis - Bactericidal

26. Sotalol - toxicity?
Constant FRACTION eliminated per unit time.(exponential)
It affects beta receptors equally and is used in AV heart block (rare).
Rheumatoid and osteoarthritis.
torsade de pointes - excessive Beta block

27. List the mechanism - clinical use - & toxicity of Busulfan.
VACUUM your Bed Room'
Due to the presence of a bulkier R group
- Alkalates DNA - CML - Pulmonary fibrosis hyperpigmentation
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.

28. Mannitol - site of action?
Foscarnet = pyroFosphate analog
proximal convoluted tubule - thin descending limb - and collecting duct
- Alkalinize urine & dialysis
- EDTA - dimercaprol - succimer - & penicillamine

29. A group of pts are rushed into the ER complaining of excessive sweating - tearing - salivation - HA - N and V - muscle twitching - difficulty breathing and diarrhea. What drug would be the most effective immediate tx
decrease
Yes
Atropine pts are suffering from Cholinestrase inhibitor poisining (Nerve gas/Organophosphate poisining)
very short acting

30. What is the mechanism of action of the Sulfonylureas?
1. Pioglitazone 2. Rosiglitazone.
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.
Tubocurarine - atracurium - mivacurium - pancuronium - vecuronium - rapacuronium

31. K+- clinical use?
depresses ectopic pacemakers - especially in digoxin toxicity
Chronic gout.
Receptors = D1=D2>beta>alpha - thus increasing heart rate (beta) and blood pressure (alpha vasoconstriction) while maintaining kidney perfusion (dopamine receptors)
Blood

32. Do Tetracyclines penetrate the CNS?
Only in limited amounts
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic
- MT polymerization inhibitor(M phase) - MOPP - lymphoma - Willm's & choriocarcinoma - neurotoxicity and myelosuppression
Local anesthetic.

33. Which individuals are predisposed to Sulfonamide - induced hemolysis?
G6PD deficient individuals
Extended spectrum penicillin: certain Gram + bacteria and Gram - rods
HTN - CHF - calcium stone formation - nephrogenic DI.
Overdose produces hepatic necrosis; acetaminophen metablolite depletes glutathione and forms toxic tissue adducts in liver.

34. MOA of Succinylcholine
BM suppression (neutropenia - anemia) - Peripheral neuropathy
Prevents the release of Ca from SR of skeletal muscle
1. Hypoglycemia (more common with 2nd - generation drugs: glyburide - glipizide) 2. Disulfiram - like effects (not seen with 2nd - generation drugs).
troponin - tropomyosin system

35. How is Vancomycin used clinically?
For serious - Gram + multidrug - resistant organisms
- EDTA - dimercaprol - succimer - & penicillamine
Butyrophenone (neuroleptic).
Aminoglycosides

36. What reversal agent could a Anes give to reverse the effects of Atropine
cortical collecting tubule
Bethanechol - Neostigmine - physostigmine
Pseudomembranous colitis (C. difficile) - fever - diarrhea
Inhibits CMV DNA polymerase

37. Furosemide - toxicity? (OH DANG)
Indirect agonist - uptake inhibitor
all except the K+ sparing diuretics Spironolactone - Triamterene - Amiloride
sedation - sleep alterations
Ototoxicity - Hypokalemia - Dehydration - Allergy (sulfa) - Nephritis (interstitial) - Gout

38. Which drug(s) cause this reaction: P450 induction(6)?
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine
Protamine Sulfate is used for rapid reversal of heparinization (positively charged molecule that binds to negatively charged heparin).
Phenothiazine (neuroleptic - antiemetic).
Tricyclic antidepressant.

39. What are four clinical activities of Aspirin?
They inhibit reuptake of NE at the nerve terminal (as does cocaine).
is resistant
Aminoglycosides
1. Antipyretic 2. Analgesic 3. Anti - inflammatory 4. Antiplatelet drug.

40. What antimuscarinic drug is useful for the tx of asthma
- Estrogen receptor antagonist - Breast CA - increased endometrial CA risk
Ipratropium
DHPG (dihydroxy-2- propoxymethyl guanine)
Pseudomonas species and Gram - rods

41. What are three possible toxicities of NSAID usage?
1. Renal damage 2. Aplastic anemia 3. GI distress
Lovastatin - Pravastatin - Simvastatin - Atorvastatin
Ibuprofen - Naproxen - and Indomethacin
SLUD (salivation - Lacrimation - urination - Defecation)as well as airway secretion - GI motility - acid secretions

42. What would be the effect on blood pressure with infusion of the alpha -2 agonist clonidine?
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.
Vd= (Amt. of drug in body/ Plasma drug conc.)
CMV Retinitis in IC pts When Ganciclovir fails
Nevirapine - Delavirdine

43. Preferential action of the Ca2+ channel blockers at cardiac muscle?
proximal convoluted tubule - thin descending limb - and collecting duct
Aminoglycosides
TMP- SMZ
cardiac muscle: Verapamil>Diltiazem>Nifedipine

44. Antiarrhythmic class IC- toxicity?
proarrhythmic
Indomethacin is used to close a patent ductus arteriosus.
penicillinase resistant
Penicillin - G

45. IV Penicillin
Anaerobes
Penicillin - G
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.
- EDTA - dimercaprol - succimer - & penicillamine

46. How does a competitive antagonist effect an agonist?
Norepinephrine
- Shifts the curve to the right - increases Km
Epinephrine
AmOxicillin has greater Oral bioavailability

47. What are the indications for using amphetamine?

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48. What are toxic side effects for Metronidazole?
Suramin
Disulfiram - like reaction with EtOH - Headache
Ganciclovir is more toxic to host enzymes
narcolepsy - obesity - and attention deficit disorder (I wouldn't recommend this)

49. What is the category - method of use - and adverse effects of Salmeterol in Asthma treatment?
reversible SLE- like syndrome
Prevents the release of calcium from the sarcoplasmic reticulum of skeletal muscle.
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.
Sildenafil fills the penis

50. How do you calculate maintenance dose?
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.
Fever/Chills - Hypotension - Nephrotoxicity - Arrhythmias
Binds Ergosterol - forms Membrane Pores that Disrupt Homeostatis
vasodilator - increases cGMP to induce smooth muscle relaxation (arterioles>veins; afterload reduction)