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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. Why would you use pralidoxime after exposure to an organophosphate?
- NaHCO3
Impairs the synthesis of vitamin K- dependent clotting factors
Pralidoxime regenerates active cholinesterase.
Premature infants - because they lack UDP- glucuronyl transferase

2. What are four thrombolytics?
1. Streptokinase 2. Urokinase 3. tPA (alteplase) - APSAC (anistreplase)
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.
Dopamine; causes its release from intact nerve terminals
Indirect agonist - uptake inhibitor

3. Which drug(s) cause this reaction: P450 inhibition(6)?
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.
Delirium - Tremor - Nephrotoxicity
- Cimetidine - ketoconazole - grapefruit juice - erythromycin - INH - sulfonamides
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility

4. What is the MOA for the Aminoglycosides?
Tubocurarine - atracurium - mivacurium - pancuronium - vecuronium - rapacuronium
Binds ergosterol - Disrupts fungal membranes
Inhibits formation of Initiation Complex - causes misreading of mRNA - Bactericidal
- Nitrate - hydroxocobalamin thiosulfate

5. What is an acronym to remember Anti - TB drugs?
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
Interstitial nephritis
Methylzanthine; desired effect is bronchodilation - may cause bronchodilation by inhibiting phosphodiesterase - enzyme involved in degrading cAMP (controversial).
RESPIre

6. For Heparin What is the Structure
decrease AP duration - affects ischemic or depolarized Purkinje and ventricular system
Large anionic polymer - acidic
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.
cholestyramine - colestipol

7. How is Ribavirin used clinically?
Constant FRACTION eliminated per unit time.(exponential)
- Daunorubicin & Doxorubicin
GI intolerance (nausea - diarrhea) - Hyperglycemia - Lipid abnormalities - Thrombocytopenia (Indinavir)
for RSV

8. MOA: Disrupt bacterial/fungal cell membranes
- N- acetylcystine
Polymyxins
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.

9. What is the mechanism of action of Ticlopidine - Clopidogrel
Staphlococcus aureus and Clostridium difficile (pseudomembranous colitis)
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.
Neutropenia
Constant FRACTION eliminated per unit time.(exponential)

10. How can Isoniazid (INH)- induced neurotoxicity be prevented?
Diarrhea
Pyridoxine (B6) administration
torsade de pointes
GI side effects. (Indomethacin is less toxic - more commonly used.)

11. What are common toxicities related to Vancomycin therapy?

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12. Hydralazine - toxicity?
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
first dose orthostatic hypotension - dizziness - headache
compensatory tachycardia - fluid retention - lupus - like syndrome
Muscarinic antagonist; competatively blocks muscarinic receptors - preventing bronchoconstriction.

13. What are three clinical uses of the Leuprolide?
Interstitial nephritis
Inhibit DNA Gyrase (topoisomerase II) - Bactericidal
- Vitamin K & fresh frozen plasma
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids

14. MOA: Block cell wall synthesis by inhib. Peptidoglycan cross - linking (7)
pulmonary edema - dehydration
scopolamine
Penicillin - Ampicillin - Ticarcillin - Pipercillin - Imipenem - Aztreonam - Cephalosporins
Norepinephrine

15. What is the MOA for Vancomycin?
- Clindamycin
Gram + cocci - Haemophilus influenza - Enterobacter aerogenes - Neisseria species - P. mirabilis - E. coli - K. pneumoniae - Serratia marcescens ( HEN PEcKS )
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine
Inhibits cell wall mucopeptide formation - Bactericidal

16. Ca2+ channel blockers - toxicity?
- Alkalates DNA - CML - Pulmonary fibrosis hyperpigmentation
GI discomfort - Acute cholestatic hepatitis - Eosinophilia - Skin rashes
Interferes with microtubule function - disrupts mitosis - inhibits growth
cardiac depression - peripheral edema - flushing - dizziness - constipation

17. Why does NE result in bradycardia?
- Clindamycin
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
Quinolones
- N- acetylcystine

18. For Heparin What is the Site of action
- Physostigmine salicylate
Aminoglycosides
Slow - limited by half lives of clotting factors
Blood

19. For Heparin What is the Ability to inhibit coagulation in vitro
new arrhythmias - hypotension
Carbenicillin - Piperacillin - and Ticarcillin
Yes
- Alkalinize urine & dialysis

20. Common toxicities associated with Fluoroquinolones?
- Alkalating agent - testicular - bladder - ovary -& lung - Nephrotoxicity & CN VIII damage.
scopolamine
GI upset - Superinfections - Skin rashes - Headache - Dizziness
1. Antiandrogen 2. Nausea 3. Vomiting

21. What is the mechanism of action of Colchicine used to treat acute gout?
Zidovudine (AZT) - Didanosine (ddI) - Zalcitabine (ddC) - Stavudine (d4T) - Lamivudine (3TC)
Beta 2 agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Use during acute exacerbation.
Depolymerizes microtubules - impairing leukocyte chemotaxis and degranulation.
Anaerobic infections (e.g. - B. fragilis - C. perfringens)

22. Explain pH dependent urinary drug elimination?
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more
Diuresis in pateints with sulfa allergy
Foscarnet = pyroFosphate analog
Activates cholinergic receptors on bladder and bowel smooth muscle - alleviating post - op and neurogenic ileus and urinary retention.

23. Cautions When using Amiodarone?
check PFTs - LFTs - and TFTs
Indomethacin is used to close a patent ductus arteriosus.
hyperchloremic metabolic acidosis - neuropathy - NH3 toxicity - sulfa allergy
1. Pioglitazone 2. Rosiglitazone.

24. What are three complications of Warfarin usage?
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium
collecting ducts
1. Bleeding 2. Teratogenicity 3. Drug - drug interactions
Mebendazole/Thiabendazole - Pyrantel Pamoate

25. Adverse effects of beta - blockers?
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia
impotence - asthma - CV effects (bradycardia - CHF - AV block) - CNS effects (sedation - sleep alterations)
- DNA intercalator - testicular & lymphomas - Pulmonary fibrosis mild myelosuppression.
Inhibit RT of HIV and prevent the incorporation of viral genome into the host DNA

26. What is the memory key for Isoniazid (INH) toxicity?
INH: Injures Neurons and Hepatocytes
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis
Prefers beta's at low doses - but at higher doses alpha agonist effects are predominantly seen.
- NaHCO3

27. What parasites are treated with Pyrantel Pamoate (more specific)?
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
Irreversibly inhibits H+/K+ ATPase in stomach parietal cells.
Dopamine
In treatment of malignant hyperthermia - due to concomitant use of halothane and succinylcholine. Also in neuroleptic malignant syndrome - a toxicity of antipsychotic drugs.

28. What is the MOA for Ampicillin and Amoxicillin?
Inhibits cell wall synthesis ( binds to PBP3). A monobactam
With an amino acid change of D- ala D- ala to D- ala D- lac
Extended spectrum penicillin: certain Gram + bacteria and Gram - rods
Same as penicillin. Extended spectrum antibiotics

29. What is the category - method of use - and adverse effects of Salmeterol in Asthma treatment?
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.
Primaquine
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.
Megaloblastic anemia - Leukopenia - Granulocytopenia

30. What is the category of drug names ending in - cycline (e.g. Tetracycline)
Albuterol - tertbutaline
1. Skin rash 2. Agranulocytosis (rare) 3. Aplastic anemia
Antibiotic - protein synthesis inhibitor.
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.

31. List the mechanism - clinical use - & toxicity of Cyclophosphamide.
No - it inhibits the release of Nor Epi
glaucoma - urinary alkalinization - metabolic alkalosis - altitude sickness
competitive inhibirot of aldosterone in the cortical collecting tubule
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.

32. For Heparin What is the Onset of action
Rapid (seconds)
1. Hypoglycemia (more common with 2nd - generation drugs: glyburide - glipizide) 2. Disulfiram - like effects (not seen with 2nd - generation drugs).
fetal renal toxicity - hyperkalemia
Clavulanic acid

33. For Warfarin What is the Lab value to monitor
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.
not a sulfonamide - but action is the same as furosemide
Atropine would also block the receptors in the ciliary muscle - causing an impairment in accommodation (cycloplegia).
PT

34. List the mechanism - clinical use - & toxicity of 5 FU.
Inhalational general anesthetic.
blocks SR Ca2+ channels
- S- phase anti - metabolite Pyr analogue - Colon - solid tumors - & BCC/ - Irreversible myelosuppression
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.

35. How is Amphotericin B administered for fungal meningitis?
Cephalosporins
Beta -2 agonist.
Sucralfate cannot work in the presence of antacids or H2 blockers because it requires an acidic environment to polymerize.
Intrathecally

36. List the specific antidote for this toxin: Methanol & Ethylene glycol
It affects beta receptors equally and is used in AV heart block (rare).
- Ethanol - dialysis - & fomepizole
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide

37. How does dantrolene work?
Does not cross
Hypersensitivity reactions
Receptors = D1=D2>beta>alpha - thus increasing heart rate (beta) and blood pressure (alpha vasoconstriction) while maintaining kidney perfusion (dopamine receptors)
Prevents the release of calcium from the sarcoplasmic reticulum of skeletal muscle.

38. What is the clinical use for Clomiphene?
- ACE inhibitors (Losartan>no cough)
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.
Treatment of infertility.
hyperaldosteronism - K+ depletion - CHF

39. What are four Sulfonylureas?
Prefers beta's at low doses - but at higher doses alpha agonist effects are predominantly seen.
Tubocurarine - atracurium - mivacurium - pancuronium - vecuronium - rapacuronium
Interferes with microtubule function - disrupts mitosis - inhibits growth
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide

40. Adverse effects of Hydrochlorothiazide?
hypokalemia - slight hyperlipidemia - hyperuricemia - lassitude - hypercalcemia - hyperglycemia
Fever/Chills - Hypotension - Nephrotoxicity - Arrhythmias
Prevents the release of ACh - Which results in muscle paralysis.
Beta - lactam antibiotics

41. List the specific antidote for this toxin: Antimuscarinic (anticholinergic)
Tubocurarine - atracurium - mivacurium - pancuronium - vecuronium - rapacuronium
Flutamide is a nonsteroidal competitive inhibitor of androgens at the testosterone receptor - used in prostate carcinoma.
Yes
- Physostigmine salicylate

42. What are the clinical uses for 3rd Generation Cephalosporins?
Irreversibly inhibits H+/K+ ATPase in stomach parietal cells.
- ACE inhibitors (Losartan>no cough)
Muscarinic antagonist; competatively blocks muscarinic receptors - preventing bronchoconstriction.
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)

43. Procainamide - toxicity?
- S- phase anti - metabolite Pyr analogue - Colon - solid tumors - & BCC/ - Irreversible myelosuppression
G6PD deficient individuals
reversible SLE- like syndrome
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic

44. What is the clinical use for Warfarin?
- A57Blue lines in gingiva & long bones - Encephalopathy & Foot drop - Abdominal colic / - Sideroblastic anemia
Chronic anticoagulation.
Tendonitis and Tendon rupture
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol

45. Furosemide increases the excretion of What ion?
cardiac muscle: Verapamil>Diltiazem>Nifedipine
Ca2+ (Loops Lose calcium)
Severe Gram - rod infections.
1. Renal damage 2. Aplastic anemia 3. GI distress

46. What are five disadvantages of Oral Contraceptives (synthetic progestins - estrogen)?
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.
Aminoglycosides - Tetracyclines
1. Taken daily 2. No protection against STDs 3. Raises triglycerides 4. Depression - weight gain - nausea - HTN 5. Hypercoagulable state
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.

47. Quinidine - toxicity?
Aplastic anemia (dose independent) - Gray Baby Syndrome
Nonspecific beta - agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Adverse effect is tachycardia (Beta 1).
cinchonism: HA - tinnitus - thrombocytopenia - torsade de pointes due to increased QT interval
Pregnant women - Children; because animal studies show Damage to Cartilage

48. What is the mechanism of action of Cyclosporine?
CMV - esp in Immunocompromised patients
Inhibits formation of Initiation Complex - causes misreading of mRNA - Bactericidal
Indomethacin is used to close a patent ductus arteriosus.
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.

49. Hydralazine - clinical use?
Lidocaine - Mexiletine - Tocainide
severe hypertension - CHF
Decreased uptake or Increased transport out of cell
Stimulates beta adrenergic receptors

50. Which RT inhibitor causes Megaloblastic Anemia?
AZT
Interstitial nephritis
Ototoxicity - Hypokalemia - Dehydration - Allergy (sulfa) - Nephritis (interstitial) - Gout
- Atropine & pralidoxime