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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 drug is used to treat Trematode/fluke (e.g. - Schistosomes - Paragonimus - Clonorchis) or Cysticercosis
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow
Praziquantel
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.
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.

2. What are toxic side effects for Metronidazole?
Chronic anticoagulation.
Disulfiram - like reaction with EtOH - Headache
Constant FRACTION eliminated per unit time.(exponential)
Gentamicin - Neomycin - Amikacin - Tobramycin - Streptomycin

3. List five common glucocorticoids.
Reversible block of histamine H2 receptors
edrophonium (extremely short acting anticholinesterase)
Forms toxic metabolites in the bacterial cell - Bactericidal
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone

4. Which drug(s) cause this reaction: Tardive dyskinesia?
1. Predisposes to viral infections and lymphoma 2. Nephrotoxic (preventable with mannitol diuresis)
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens
proximal convoluted tubule - thin descending limb - and collecting duct
- Antipsychotics

5. How does botulinum toxin result in respiratory arrest?
Bleeding.
Prevents the release of ACh - Which results in muscle paralysis.
Mebendazole/Thiabendazole - Pyrantel Pamoate
Decreases synthesis of Mycolic Acid

6. Why is Cilastatin administered with Imipenem?
To inhibit renal Dihydropeptidase I and decrease Imipenem inactivation in the renal tubules
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.
Pralidoxime regenerates active cholinesterase.
Prevents the release of ACh - Which results in muscle paralysis.

7. Ca2+ channel blockers - mechanism?
Impairs the synthesis of vitamin K- dependent clotting factors
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility
- Nitrate - hydroxocobalamin thiosulfate
Neostigmine - pyridostigmine edrophonium - physostigmine echothiophate

8. Why would you give a drug like pancuronium or succinylcholine?
Tricyclic antidepressant.
Clavulanic acid
Useful in muscle paralysis during surgery or mechanical ventilation.
Benzathine penicillin G

9. Hydralazine - class and mechanism?
vasodilator - increases cGMP to induce smooth muscle relaxation (arterioles>veins; afterload reduction)
Protamine sulfate
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.
Fast vs. Slow Acetylators

10. Adverse effects of Nifedipine - verapamil?
Aminoglycosides - Tetracyclines
dizziness - flushing - constipation (verapamil) - nausea
constipation - flushing - edema - CV effects (CHF - AV block - sinus node depression) - and torsade de pointes (Bepridil)
Amphotericin B - Nystatin - Fluconazole/azoles

11. Why does atropine dilate the pupil?
Nifedipine - Verapamil - Diltiazem
- partial agonist can have increased - decreased - /A21or equal potency as full agonist. - Potency is an independent factor.
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.
Blocking muscarinic receptors in the circular fibers of the eye - results in unopposed action of radial muscles to dilate.

12. What is the chemical name for Ganciclovir?
Large anionic polymer - acidic
DHPG (dihydroxy-2- propoxymethyl guanine)
glaucoma - urinary alkalinization - metabolic alkalosis - altitude sickness
Rifampin (DOC) - minocycline

13. What are nine findings of Iatrogenic Cushing's syndrome caused by glucocorticoid therapy?
1. Buffalo hump 2. Moon facies 3. Truncal obesity 4. Muscle wasting 5. Thin skin 6. Easy bruisability 7. Osteoporosis 8. Adrenocortical atrophy 9. Peptic ulcers
Similar to cyclosporine; binds to FK- binding protein - inhibiting secretion of IL-2 and other cytokines.
Mechanism unknown; possibly inhibits gluconeogenesis and increases glycolysis; effect is to decrease serum glucose levels
Hypersensitivity reactions

14. What is the clinical use for Sildenafil (Viagra)?
Flecainide - Encainide - Propafenone
- Chloramphenicol
Erectile dysfunction.
Inhibit RT of HIV and prevent the incorporation of viral genome into the host DNA

15. Classes of antihypertensive drugs?
Scopolamine
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors
- Shifts the curve down - reduces Vmax
Aluminum sucrose sulfate polymerizes in the acid environment of the stomach and selectively binds necrotic peptic ulcer tissue. Acts as a barrier to acid - pepsin - and bile.

16. What are the clinical indications for Azole therapy?
Systemic mycoses
No - it inhibits the release of Nor Epi
Increased systolic and pulse pressure - decreased diastolic pressure - and little change in mean pressure.
competitive inhibirot of aldosterone in the cortical collecting tubule

17. Why are albuterol and terbutaline effective in tx of acute asthmatic attacks?
These B-2 agonists cause respiratory smooth muscle to relax.
Erectile dysfunction.
Neurotoxicity - Acute renal tubular necrosis
- DNA intercalator - Hodgkin's - myeloma - sarcoma - and solid tumors - Cardiotoxicity & alopecia

18. Which antimicrobials inhibit protein synthesis at the 50S subunit? (4)
Lipoxygenase
1) Chloramphenical = bacteriostatic 2) Erythromycin = bacteriostatic 3) Lincomycin = bacteriostatic 4)cLindamycin = bacteriostatic
1. Meningococcal carrier state 2. Chemoprophylaxis in contacts of children with H. influenzae type B
Tendonitis and Tendon rupture

19. Specifically - How does Foscarnet inhibit viral DNA pol?
Binds to the Pyrophosphate Binding Site of the enzyme
physostigmine
Extended spectrum penicillin: certain Gram + bacteria and Gram - rods
G6PD deficient individuals

20. Which diuretics decrease urine Ca2+?
Binds Ergosterol - forms Membrane Pores that Disrupt Homeostatis
1. Antipyretic 2. Analgesic 3. Anti - inflammatory
Chronic anticoagulation.
thiazides - amiloride

21. What is the mechanism of action of Acetaminophen?
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.
Competitive inibitor of progestins at progesterone receptors.
scopolamine
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.

22. What is the mecanism of action - effective period - and ineffective period of use for Cromolyn in treating Asthma?
effective in torsade de pointes and digoxin toxicity
- Atropine & pralidoxime
Prevents release of mediators from mast cells. Effective only for the prophylaxis of asthma. Not effective during an acute attack.
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.

23. What is are two clinical uses of Cyclosporine?
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.
- S- phase anti - metabolite folate analogue - Luk - Lymp - sarc - RA - & psoriasis / - Reversible myelosuppression
Captopril - Enalapril - Lisinopril
Rifampin (DOC) - minocycline

24. List the specific antidote for this toxin: Carbon monoxide
The PTT.
-100% oxygen - hyperbaric
Chronic gout.
Sucralfate cannot work in the presence of antacids or H2 blockers because it requires an acidic environment to polymerize.

25. What are the clinical indications for bethanechol?
Nevirapine - Delavirdine
Activates cholinergic receptors on bladder and bowel smooth muscle - alleviating post - op and neurogenic ileus and urinary retention.
- Hydralazine - Procainamide - INH - phenytoin
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia

26. Name the common Non - Nucleoside Reverse Transcriptase Inhibitors
Ataxia - Dizziness - Slurred speech
Praziquantel
Nevirapine - Delavirdine
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.

27. What is the enzyme inhibited - the effect of this inhibition - and the clinical use of the antiandrogren Finasteride?
NO
Small lipid - soluble molecule
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.
Finasteride inhibits 5 Alpha - reductase - this decreases the conversion of testosterone to dihydrotestosterone - useful in BPH

28. What is the category of drug names ending in - navir (e.g. Saquinavir)
Non - Nucleosides
With an amino acid change of D- ala D- ala to D- ala D- lac
toxic
Protease inhibitor.

29. What microorganisms is Aztreonam not effective against?
impotence - exacerbation of asthma - CV effects - CNS effects - may mask hypoclycemia
torsade de pointes - excessive Beta block
Gram + and Anerobes
Aminoglycosides - Tetracyclines

30. Isopoterenol was given to a patient with a developing AV block - why?
Pralidoxime regenerates active cholinesterase.
Stimulates beta adrenergic receptors
1. Acarbose 2. Miglitol
Pyridoxine (B6) administration

31. What additional side effects exist for Ampicillin?
Neutropenia (ticlopidine); reserved for those who cannot tolerate aspirin.
Rash - Pseudomembranous colitis
fetal renal toxicity - hyperkalemia
Give an antichloinesterase - neostigmine - edrophonium - etc

32. ADH antagonists - site of action?
Triple sulfas or SMZ
Phenothiazine (neuroleptic - antiemetic).
collecting ducts
sedation - positive Coombs' test

33. List the mechanism - clinical use - & toxicity of Methotrexate.
G6PD deficient individuals
- S- phase anti - metabolite folate analogue - Luk - Lymp - sarc - RA - & psoriasis / - Reversible myelosuppression
Nucleosides
GI discomfort - Acute cholestatic hepatitis - Eosinophilia - Skin rashes

34. List the specific antidote for this toxin: Amphetamine
No
The only local anesthetic with vasoconstrictive properties.
Premature infants - because they lack UDP- glucuronyl transferase
- Ammonium Chloride

35. What are the clinical uses for Ticlopidine - Clopidogrel?
Penicillin.
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.
Antileukotriene; blocks synthesis by lipoxygenase.
impotence - exacerbation of asthma - CV effects - CNS effects - may mask hypoclycemia

36. Norepi feedbacks and inhibits the presynaptic receptor by What mechanism
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine
Ciprofloxacin - Norfloxacin - Ofloxacin - Grepafloxacin - Enoxacin - Nalidixic acid
Binding to the presynaptic alpha 2 release modulating receptors
- EDTA - dimercaprol - succimer - & penicillamine

37. Ethacrynic Acid - clinical use?
Diuresis in pateints with sulfa allergy
Pentavalent Antimony
Verapamil - Diltiazem - Bepridil
- Deferoxamine

38. How is Amphotericin B used clinically?
No - it inhibits the release of Nor Epi
carbonic anhydrase inhibitors - K+ sparing diuretics
Wide spectrum of systemic mycoses: Cryptococcus - Blastomyces - Coccidioides - Aspergillus - Histoplasma - Candida - Mucor
Blocks viral penetration/uncoating; may act to buffer the pH of the endosome

39. As an Anes you want to use a depolarizing neuromuscular blocking drug on your pt - What do you use
Potent immunosuppressive used in organ transplant recipients.
Erythromycin - Azithromycin - Clarithromycin
Zidovudine (AZT) - Didanosine (ddI) - Zalcitabine (ddC) - Stavudine (d4T) - Lamivudine (3TC)
Succinylcholine

40. What reversal agent could a Anes give to reverse the effects of Atropine
- S- phase anti - metabolite Pyr analogue - Colon - solid tumors - & BCC/ - Irreversible myelosuppression
Inhibits reabsorption of uric acid.
Bethanechol - Neostigmine - physostigmine
Bismuth and Amoxicillin or Tetracycline; against Helobacter pylori

41. Antiarrhythmic class IV- effects?
- Normalize K+ - Lidocaine - & Anti - dig Mab
decrease conduction velocity - increase ERP - increase PR interval
- Alkalating agent - testicular - bladder - ovary -& lung - Nephrotoxicity & CN VIII damage.
Aminoglycosides - Tetracyclines

42. For Warfarin What is the Treatment for overdose
IV vitamin K and fresh frozen plasma
Inhibits DNA dependent RNA polymerase
Slow - limited by half lives of clotting factors
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention

43. How does Ganciclovir's toxicity relate to that of Acyclovir?
Binds to the Pyrophosphate Binding Site of the enzyme
- Phenytoin
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.
Ganciclovir is more toxic to host enzymes

44. What enzyme is responsible for the degredation of Ach
Acetylcholine esterase
Misoprostol is contraindicated in women of childbearing potential because it is an abortifacient.
Parkinson patients benefit from antimuscarinic agents through its inhibitory action within the indirect pathway.
Same as penicillin. Extended spectrum antibiotics

45. Adverse effects of Hydrochlorothiazide?
1. Hot flashes 2. Ovarian enlargement 3. Multiple simultaneous pregnancies 4. Visual disturbances
cardiac muscle: Verapamil>Diltiazem>Nifedipine
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
hypokalemia - slight hyperlipidemia - hyperuricemia - lassitude - hypercalcemia - hyperglycemia

46. What is the clinical utility of cocaine?
The only local anesthetic with vasoconstrictive properties.
- Alkalate DNA - Brain tumors - CNS toxicity
Methylation of rRNA near Erythromycin's ribosome binding site
Rheumatoid and osteoarthritis.

47. For Heparin What is the Ability to inhibit coagulation in vitro
Gram + and Anerobes
- Aminocaproic acid
Post - op and neurogenic ileus and urinary retention - myasthenia gravis - and reversal of neuromuscular junction blockade (post - op) through anticholinesterase activity.
Yes

48. What are Methicillin - Nafcillin - and Dicloxacillin used for clinically?
hypokalemia - slight hyperlipidemia - hyperuricemia - lassitude - hypercalcemia - hyperglycemia
Interstitial nephritis
Staphlococcus aureus
Pseudomembranous colitis (C. difficile) - fever - diarrhea

49. Antiarrhythmic class IV- clinical use?
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine
- Tetracycline
prevention of nodal arrhythmias (SVT)
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.

50. Explain differences between full and partial agonists(2).
loop diuretics - thiazides
Decreased uptake or Increased transport out of cell
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.
- Act on same receptor - Full has greater efficacy