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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. If a patient is given hexamethonium - What would happen to his/her heart rate?
It would increase to ~ 100 beats/min. Both sympathetic and vagal stimulation would be knocked out - but the SA node has an intrinsic pace of 100 beats/min - Which is normally checked by vagal stimulation.
Methylxanthine.
sedation - sleep alterations
- Hydralazine - Procainamide - INH - phenytoin

2. Acetaldehyde is metabolized by Acetaldehyde dehydrogenase - Which drug inhibs this enzyme?
- Disulfram & also sulfonylureas - metronidazole
Sucralfate cannot work in the presence of antacids or H2 blockers because it requires an acidic environment to polymerize.
compensatory tachycardia - fluid retention - lupus - like syndrome
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia

3. How are Sulfonamides employed clinically?
thick ascending limb
Gram + - Gram - - Norcardia - Chlamydia
1. Streptokinase 2. Urokinase 3. tPA (alteplase) - APSAC (anistreplase)
Praziquantel

4. What type of gout is treated with Probenacid?
VACUUM your Bed Room'
cortical collecting tubule
Short.
Chronic gout.

5. What is the category of drug names ending in - ipramine (e.g. Imipramine)
It must be Phosphorylated by Viral Thymidine Kinase
Oral
Tricyclic antidepressant.
- Ammonium Chloride

6. What is the category and mechanism of action of Zileuton in Asthma treatment?
Antileukotriene; blocks synthesis by lipoxygenase.
Due to the presence of a bulkier R group
Protease inhibitor.
1) Hypersensitivity reactions 2) Increased nephrotoxicity of Aminoglycosides 3) Disulfiram - like reaction with ethanol (those with a methylthiotetrazole group - e.g. - cefamandole)

7. List the mechanism - clinical use - & toxicity of Paclitaxel.
No - hemicholinum block the uptake of Choline and thus Ach synthesis
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.
Spironolactone - Triamterene - Amiloride (the K+ STAys)

8. What are the four conditions in Which Omeprazole - Lansoprazole is used?
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome
Inhibit RT of HIV and prevent the incorporation of viral genome into the host DNA
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis

9. List some specifics of lead poisoning(4)?
Inhibits DNA dependent RNA polymerase
fetal renal damage - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
- A57Blue lines in gingiva & long bones - Encephalopathy & Foot drop - Abdominal colic / - Sideroblastic anemia
1. Skin rash 2. Agranulocytosis (rare) 3. Aplastic anemia

10. What is treated with Chloroquine - Quinine - Mefloquine?
Short.
Malaria (P. falciparum)
hyperaldosteronism - K+ depletion - CHF
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity

11. List the mechanism - clinical use - & toxicity of Cisplatin.
- Alkalating agent - testicular - bladder - ovary -& lung - Nephrotoxicity & CN VIII damage.
Liver
Butyrophenone (neuroleptic).
NO AP duration effect. useful in V- tach that progresses to V- fib and in intractable SVT Last RESORT

12. Why are the Sulfonylureas inactive in IDDM (type -1)?
Albuterol - tertbutaline
CMV - esp in Immunocompromised patients
GnRH analog with agonist properties When used in pulsatile fashion and antagonist properties When used in continuous fashion - causing a transient initial burst of LH and FSH
Because they require some residual islet function.

13. Describe the MOA of Interferons (INF)
Gram + - Gram - - Norcardia - Chlamydia
Useful in muscle paralysis during surgery or mechanical ventilation.
Glycoproteins from leukocytes that block various stages of viral RNA and DNA synthesis
- NaHCO3

14. Is resistant to penicillinase?
Imipenem
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.
- Methylene blue
It affects beta receptors equally and is used in AV heart block (rare).

15. Which drug(s) cause this reaction: Agranulocytosis (3)?
- Cloazapine - carbamazapine - colchicine - PTU
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs
TMP- SMZ (DOC) - aerosolized pentamidine
Prevents the release of Ca from SR of skeletal muscle

16. What populations are Floroquinolones contraindicated in? Why?
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia
It acts presynaptically to increase NE release.
Increases mean - systolic - and diastolic bp - while there is little change in pulse pressure.
Pregnant women - Children; because animal studies show Damage to Cartilage

17. What is the category - desired effect - and adverse effect of Isoproterenol in the treatment of Asthma?
Nonspecific beta - agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Adverse effect is tachycardia (Beta 1).
decrease
Triple Therapy' 2 Nucleoside RT Inhibitors with a Protease Inhibitor
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.

18. Which drug(s) cause this reaction: Torsade de pointes (2)?
In treatment of malignant hyperthermia - due to concomitant use of halothane and succinylcholine. Also in neuroleptic malignant syndrome - a toxicity of antipsychotic drugs.
- EDTA - dimercaprol - succimer - & penicillamine
No - hemicholinum block the uptake of Choline and thus Ach synthesis
- Class III antiarrhythmics (sotalol) - class IA (quinidine)

19. What is the MOA of Ganciclovir?
Anaerobes
Bethanechol - Neostigmine - physostigmine
Inhibits CMV DNA polymerase
toxic

20. Which drug(s) cause this reaction: P450 induction(6)?
1. Phospholipase A2 is prevented from releasing arachidonic acid 2. Decreases protein synthesis thus lowering amount of Cyclooxygenase enzymes
Epinephirine(Alpha1 -2 and Beta 1 -2)
Binding to the presynaptic alpha 2 release modulating receptors
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine

21. What is Nifurtimox administered for?

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22. What is the mechanism of action of Colchicine used to treat acute gout?
Depolymerizes microtubules - impairing leukocyte chemotaxis and degranulation.
1)Binds penicillin - binding proteins 2) Blocks transpeptidase cross - linking of cell wall 3) Activates autolytic enzymes
increase AP duration - increase ERP - increase QT interval - for use When other arrhythmics fail
orthostatic and exercise hypotension - sexual dysfunction - diarrhea

23. For Heparin What is the Mechanism of action
collecting ducts
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents
Anaerobes
Activates antithrombin III

24. Which RT inhibitors cause a Rash?
Binding to the presynaptic alpha 2 release modulating receptors
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions
Non - Nucleosides
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide

25. Name four Antiarrhythmic drugs in class III.
Sotalol - Ibutilide - Bretylium - Amiodarone
ARF - shock - drug overdose - decrease intracranial/intraocular pressure
AZT - to reduce risk of Fetal Transmission
Cyclooxygenases (COX I - COX II).

26. What are common side effects of Protease Inhibitors?
GI intolerance (nausea - diarrhea) - Hyperglycemia - Lipid abnormalities - Thrombocytopenia (Indinavir)
Protease Inhibitors and Reverse Transcriptase Inhibitors
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
Carbachol - pilocarpine - physostigmine - echothiophate

27. What is the category and mechanism of action of Zafirlukast in Asthma treatment?
AZT
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia
Antileukotriene; blocks leukotriene receptors.
Beta - lactam antibiotics

28. What is the MOA of Isoniazid (INH)?
Decreases synthesis of Mycolic Acid
Bismuth and Amoxicillin or Tetracycline; against Helobacter pylori
Muscarinic antagonist; competatively blocks muscarinic receptors - preventing bronchoconstriction.
Selectively inhibit cyclooxygenase (COX) isoform 2 - Which is found in inflammatory cells nad mediates inflammation and pain; spares COX-1 Which helps maintain the gastric mucosa.

29. What are common toxicities associated with Tetracyclines?

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30. Resistance mechanisms for Chloramphenicol
Modification via Acetylation
- DNA intercalator - testicular & lymphomas - Pulmonary fibrosis mild myelosuppression.
Mg = Must go to the bathroom.
Treatment of infertility.

31. What is the mechanism of Leuprolide?
- DNA intercalator - Hodgkin's - myeloma - sarcoma - and solid tumors - Cardiotoxicity & alopecia
GnRH analog with agonist properties When used in pulsatile fashion and antagonist properties When used in continuous fashion - causing a transient initial burst of LH and FSH
Reversible block of histamine H2 receptors
Ibuprofen - Naproxen - and Indomethacin

32. How does Ganciclovir's toxicity relate to that of Acyclovir?
Ganciclovir is more toxic to host enzymes
effective in torsade de pointes and digoxin toxicity
1) Aminoglycosides = bactericidal 2) Tetracyclines = bacteriostatic
Doxycycline - because it is fecally eliminated

33. A 57 yo heart failure pt develops cardiac decompensation - What drug will give you adequate perfusion of his kidneys as well as tx for his Hypotension
Dopamine
Same as penicillin. Act as narrow spectrum antibiotics
Oral treatment of superficial infections
post MI and digitalis induced arrhythmias

34. K+ sparing diuretics - toxicity?
Primaquine
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)
Decreases synthesis of Mycolic Acid
hyperkalemia - endocrine effects (gynecomastia - anti - androgen)

35. Which drug(s) cause this reaction: Cardiac toxicity?
No - it inhibits the release of Nor Epi
- Daunorubicin & Doxorubicin
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine
Clavulanic acid

36. Which drug(s) cause this reaction: Drug induced Parkinson's (4) ?
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.
- Haloperidol - chlorpromazine - reserpine - MPTP
impotence - asthma - CV effects (bradycardia - CHF - AV block) - CNS effects (sedation - sleep alterations)

37. Side effects of Isoniazid (INH)?
TCA
Butyrophenone (neuroleptic).
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome
- Tamoxifen

38. What is the clinical use for Nystatin?
Topical and Oral - for Oral Candidiasis (Thrush)
DOC in diagnosing and abolishing AV nodal arrhythmias
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.
-100% oxygen - hyperbaric

39. What is the MOA for Acyclovir?
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.
NO AP duration effect. useful in V- tach that progresses to V- fib and in intractable SVT Last RESORT
Potent immunosuppressive used in organ transplant recipients.
Inhibit viral DNA polymerase

40. What are common toxic side effects of Sulfonamides? (5)
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia
- Hypersensitivity reactions - Hemolysis - Nephrotoxicity (tubulointerstitial nephritis) - Kernicterus in infants Displace other drugs from albumin (e.g. - warfarin)
Inhibition of 50S peptidyl transferase - Bacteriostatic
1. Gastric ulceration 2. Bleeding 3. Hyperventilation 4. Reye's syndrome 5. Tinnitus (CN VIII)

41. What is the formula for Clearance (CL)
Inhibits reabsorption of uric acid.
CL= (rate of elimination of drug/ Plasma drug conc.)
fetal renal toxicity - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
Useful in muscle paralysis during surgery or mechanical ventilation.

42. What is the clinical use for Warfarin?
- Glucocorticoid withdrawal
Depolymerizes microtubules - impairing leukocyte chemotaxis and degranulation.
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).
Chronic anticoagulation.

43. What is are two clinical uses of Cyclosporine?
atropine - homatropine - tropicamide
Antifungal.
cross - allergenic
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.

44. Which drug(s) cause this reaction: Diabetes insipidus?
Inhibt Assembly of new virus by Blocking Protease Enzyme
cross - allergenic
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia
- Lithium

45. What two vasodilators require simultaneous treatment with beta blockers to prevent reflex tachycardia and diuretics to prevent salt retention?
- ED 50 is less than the Km (less than 50% of receptors)
Hydralazine and Minoxidil
Pentamidine
Due to the presence of a bulkier R group

46. What enzyme is responsible for the degredation of Ach
Acetylcholine esterase
Gemfibrozil - Clofibrate
1. Phospholipase A2 is prevented from releasing arachidonic acid 2. Decreases protein synthesis thus lowering amount of Cyclooxygenase enzymes
1. Taken daily 2. No protection against STDs 3. Raises triglycerides 4. Depression - weight gain - nausea - HTN 5. Hypercoagulable state

47. List the mechanism - clinical use - & toxicity of Nitrosureas.
Atropine would also block the receptors in the ciliary muscle - causing an impairment in accommodation (cycloplegia).
- Alkalate DNA - Brain tumors - CNS toxicity
Protamine Sulfate is used for rapid reversal of heparinization (positively charged molecule that binds to negatively charged heparin).
Benzathine penicillin G

48. Adverse effects of beta - blockers?
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic
In treatment of malignant hyperthermia - due to concomitant use of halothane and succinylcholine. Also in neuroleptic malignant syndrome - a toxicity of antipsychotic drugs.
impotence - asthma - CV effects (bradycardia - CHF - AV block) - CNS effects (sedation - sleep alterations)
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.

49. A common side effects of Interferon (INF) treatment is?
sedation - positive Coombs' test
- N- acetylcystine
Neutropenia
Cimetidine is a potent inhibitor of P450; it also has an antiandrogenic effect and decreases renal excretion of creatinine. Other H2 blockers are relatively free of these effects.

50. Aztreonam ________ to penicillinase
- Ammonium Chloride
dizziness - flushing - constipation (verapamil) - nausea
is resistant
ACIDazolamide' causes acidosis