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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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1. Name three ACE inhibitors?
Malaria (P. falciparum)
GI side effects. (Indomethacin is less toxic - more commonly used.)
Inhibits bacterial Dihydrofolate Reductase - Bacteriostatic
Captopril - Enalapril - Lisinopril

2. What are three clinical uses of the NSAIDs?
Neurotoxicity - Acute renal tubular necrosis
sedation - sleep alterations
1. Antipyretic 2. Analgesic 3. Anti - inflammatory
very short acting

3. Adverse effects of ganglionic blockers?
1) Hypersensitivity reactions 2) Increased nephrotoxicity of Aminoglycosides 3) Disulfiram - like reaction with ethanol (those with a methylthiotetrazole group - e.g. - cefamandole)
severe orthostatic hypotension - blurred vision - constipation - sexual dysfunction
Inhibits bacterial Dihydrofolate Reductase - Bacteriostatic
prevention of nodal arrhythmias (SVT)

4. What is the mechanism of action of Misoprostol?
Norepinephrine (Alpha1 -2 and beta 1)
- B51Naloxone / naltrexone (Narcan)
Misoprostol is a PGE1 analog that increases the production and secretion of the gastic mucous barrier.
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide

5. What is used to reverse the action of Heparin?
atropine - homatropine - tropicamide
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.
Protamine Sulfate is used for rapid reversal of heparinization (positively charged molecule that binds to negatively charged heparin).
- Nitrate - hydroxocobalamin thiosulfate

6. Ibutilide - toxicity?
Non - Nucleosides
torsade de pointes
Resistant Gram - infections
- Methotrexate - 5 FU - 6 mercaptopurine

7. How is Rifampin used clinically?
Mebendazole/Thiabendazole - Pyrantel Pamoate
Rifampin (DOC) - minocycline
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs
Hormone synthesis inhibition (Gynecomastia) - Liver dysfunction (Inhibits CYP450) - Fever - Chills

8. What are the clinical indications for neostigmine?
Post - op and neurogenic ileus and urinary retention - myasthenia gravis - and reversal of neuromuscular junction blockade (post - op) through anticholinesterase activity.
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.
Yes - it does not cross the placenta.

9. List the specific antidote for this toxin: Cyanide
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors
- Nitrate - hydroxocobalamin thiosulfate
Rapid (seconds)

10. Can Warfarin be used during pregnancy?
IV vitamin K and fresh frozen plasma
Alpha -1 antagonist
No - warfarin - unlike heparin - can cross the placenta.
- reduction - oxy - & hydrolysis - H2O sol. Polar product - P450

11. 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.
- Airway - Breathing - Circulation - Dextrose (thiamine & narcan) - ABCD
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow
Binds to cyclophilins (peptidyl proline cis - trans isomerase) - blocking the differentiation and activation of T cells mainly by inhibiting the production of IL-2 and its receptor.

12. What is the category of drug names ending in - triptyline (e.g. Amitriptyline)
Beta lactams - inhibit cell wall synthesis - Bactericidal
- Triggers apoptosis - CLL - Hodgkin's in MOPP - Cushing - like syndrome
compensatory tachycardia - fluid retention - lupus - like syndrome
Tricyclic antidepressant.

13. List the mechanism - clinical use - & toxicity of Cyclophosphamide.
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
Inhibits cell wall synthesis ( binds to PBP3). A monobactam
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.

14. Digoxin v. Digitoxin: protein binding?
proximal convoluted tubule - thin descending limb - and collecting duct
Albuterol - tertbutaline
Digitoxin 70% Digoxin 20-40%
hypertension - angina - arrhythmias

15. How do the Protease Inhibitors work?
Methylzanthine; desired effect is bronchodilation - may cause bronchodilation by inhibiting phosphodiesterase - enzyme involved in degrading cAMP (controversial).
Inhibt Assembly of new virus by Blocking Protease Enzyme
Cephalosporins
Butyrophenone (neuroleptic).

16. What is combined with Ampicillin - Amoxicillin - Carbenicillin - Piperacillin - and Ticarcillin to enhance their spectrum?
- reduction - oxy - & hydrolysis - H2O sol. Polar product - P450
Beta - lactamase cleavage of Beta - lactam ring
Clavulanic acid
Acetaminophen has antipyretic and analgesic properties - but lacks anti - inflammatory properties.

17. K+ sparing diuretics - site of action?
Neutropenia (ticlopidine); reserved for those who cannot tolerate aspirin.
cortical collecting tubule
- Methotrexate - 5 FU - 6 mercaptopurine
Rifampin

18. What is the category and mechanism of action of Zafirlukast in Asthma treatment?
Antileukotriene; blocks leukotriene receptors.
Irreversibly inhibits H+/K+ ATPase in stomach parietal cells.
Oral
Modification via Acetylation

19. ACE inhibitors - mechanism?
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased
Verapamil - Diltiazem - Bepridil
GI upset
- Alkalating agent - testicular - bladder - ovary -& lung - Nephrotoxicity & CN VIII damage.

20. Name five Antiarrhythmic drugs in class II?
- Clindamycin
Ototoxicity - Hypokalemia - Dehydration - Allergy (sulfa) - Nephritis (interstitial) - Gout
- Tricyclic antidepressants
propanolol - esmolol - metoprolol - atenolol - timolol

21. For Warfarin What is the Duration of action
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions
Chronic (weeks or months)
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
effective in torsade de pointes and digoxin toxicity

22. Which diuretics increase urine NaCl?
- Normalize K+ - Lidocaine - & Anti - dig Mab
G6PD deficient individuals
- Penicillin
all of them

23. What is the MOA for Methicillin - Nafcillin - and Dicloxacillin?
Does not cross
Same as penicillin. Act as narrow spectrum antibiotics
Giardiasis - Amoebic dysentery (E. histolytica) - Bacterial vaginitis (Gardnerella vaginalis) - Trichomonas
- Daunorubicin & Doxorubicin

24. What is the mechanism of action and clinical use of the antiandrogens Ketoconazole and Spironolactone?
Neutropenia
Inhibit steroid synthesis - used in the treatment of polycystic ovarian syndrome to prevent hirsutism.
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
Cephalosporins

25. Adverse effects of Clonidine?
post MI and digitalis induced arrhythmias
dry mouth - sedation - severe rebound hypertension
Quinidine - Amiodarone - Procainamide - Disopyramide
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis

26. Acetazolamide - site of action?
Albuterol - tertbutaline
cortical collecting tubule
RESPIre
proximal convoluted tubule

27. How can the toxic effects of TMP be ameliorated?
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention
With supplemental Folic Acid
Increase target cell response to insulin.
Protease Inhibitors and Reverse Transcriptase Inhibitors

28. What is the memory key for the action of Sildenafil (Viagra)?
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.
DHPG (dihydroxy-2- propoxymethyl guanine)
Sildenafil fills the penis
local anesthetic. CNS stimulation or depression. CV depression.

29. Common toxicities associated with Fluoroquinolones?
1. Bleeding 2. Teratogenicity 3. Drug - drug interactions
GI upset - Superinfections - Skin rashes - Headache - Dizziness
DHPG (dihydroxy-2- propoxymethyl guanine)
Benzathine penicillin G

30. ACE inhibitors - toxicity?
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone
fetal renal damage - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
Beta antagonist.
penicillinase resistant

31. How would you treat African Trypanosomiasis (sleeping sickness)?
Suramin
INH: Injures Neurons and Hepatocytes
- Act on same receptor - Full has greater efficacy
Nevirapine - Delavirdine

32. For Heparin What is the Duration of action
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.
It must be Phosphorylated by Viral Thymidine Kinase
- Upper respiratory tract infections - pneumonias - STDs: Gram+ cocci (streptococcal infect in pts allergic to penicillin) - Mycoplasma - Legionella - Chlamydia - Neisseria
Acute (hours)

33. Which diuretics increase urine Ca2+?
Can affect absorption - bioavailability - or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying.
- Triggers apoptosis - CLL - Hodgkin's in MOPP - Cushing - like syndrome
- Oxalic acid - Acidosis & nephrotoxicity
loop diuretics - spironolactone

34. Antiarrhythmic class IC- effects?
The PT.
decrease the slope of phase 4 - increase PR interval (the AV node is particularly sensitive)
Beta -2 agonist.
NO AP duration effect. useful in V- tach that progresses to V- fib and in intractable SVT Last RESORT

35. Which drug(s) cause this reaction: Disulfram - like reaction (4) ?
Rapid (seconds)
hypertension - CHF - diabetic renal disease
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
- Metronidazole - certain cephalosporins - procarbazine - sulfonylureas

36. List the specific antidote for this toxin: Heparin
- Chloramphenicol - benzene - NSAIDS - PTU - phenytoin
- Metronidazole - certain cephalosporins - procarbazine - sulfonylureas
- Protamine
Binds ergosterol - Disrupts fungal membranes

37. What antimicrobial class is Aztreonam syngergestic with?
Aminoglycosides
very short acting
- Methotrexate - 5 FU - 6 mercaptopurine
- Oral Contraceptives

38. What is the clincial use for Misoprostol?
- Methylene blue
Prevention of NSAID- induced peptic ulcers - maintains a PDA.
Beta Blockers
Diarrhea - Urination - Miosis - Bronchospasm - Bradycardia - Excitation of skeletal muscle and CNS - Lacrimation - Sweating - and Salivation = DUMBBELS; also abdominal cramping

39. MOA of Succinylcholine
Lidocaine - Mexiletine - Tocainide
Prevents the release of Ca from SR of skeletal muscle
Tendonitis and Tendon rupture
H2 antagonist

40. What is the MOA for Carbenicillin - Piperacillin - and Ticarcillin?
Inhibits formation of Initiation Complex - causes misreading of mRNA - Bactericidal
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
Same as penicillin. Extended spectrum antibiotics
- Vitamin K & fresh frozen plasma

41. Furosemide - clinical use?
Directly of indirectly aid conversion of plasminogen to plasmin Which cleaves thrombin and fibrin clots. (It is claimed that tPA specifically converts fibrin - bound plasminogen to plasmin.)
1. Taken daily 2. No protection against STDs 3. Raises triglycerides 4. Depression - weight gain - nausea - HTN 5. Hypercoagulable state
- Act on same receptor - Full has greater efficacy
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia

42. MOA: Block protein synthesis at 30s subunit
Inhibits DNA dependent RNA polymerase
Prevention of NSAID- induced peptic ulcers - maintains a PDA.
Doxycycline - because it is fecally eliminated
Aminoglycosides - Tetracyclines

43. List the mechanism - clinical use - & toxicity of Prednisone.

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44. What are Fluoroquinolones indicated for? (3)
1.Gram - rods of the Urinary and GI tracts (including Pseudomonas) 2.Neisseria 3. Some Gram + organisms
Protease inhibitor.
- Shifts the curve to the right - increases Km
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)

45. Antiarrhythmic class IV- toxicity?
constipation - flushing - edema - CV effects (CHF - AV block - sinus node depression) - and torsade de pointes (Bepridil)
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.
PT
- Phenytoin

46. Procainamide - toxicity?
Inhibits Viral DNA polymerase
- Hypersensitivity reactions - Hemolysis - Nephrotoxicity (tubulointerstitial nephritis) - Kernicterus in infants Displace other drugs from albumin (e.g. - warfarin)
reversible SLE- like syndrome
block Na+ channels in the cortical collecting tubule

47. Isopoterenol was given to a patient with a developing AV block - why?
- B51Naloxone / naltrexone (Narcan)
Stimulates beta adrenergic receptors
increase AP duration - increase ERP - increase QT interval - for use When other arrhythmics fail
Post - op and neurogenic ileus and urinary retention - myasthenia gravis - and reversal of neuromuscular junction blockade (post - op) through anticholinesterase activity.

48. Which drug(s) cause this reaction: Oto and Nephrotoxicity (3)?
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.
- Act on same receptor - Full has greater efficacy
- Acetaldehyde - Nausea - vomiting - headache - & hypotension
- aminoglycosides - loop diuretics - cisplatin

49. Adverse effects of Captopril?
Epinephirine(Alpha1 -2 and Beta 1 -2)
fetal renal toxicity - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
cyanide toxicity (releases CN)
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)

50. Explain potency in relation to full and partial agonists(2).
It affects beta receptors equally and is used in AV heart block (rare).
- partial agonist can have increased - decreased - /A21or equal potency as full agonist. - Potency is an independent factor.
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more
prevention of nodal arrhythmias (SVT)