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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 are the products and their toxicities of the metabolism of ethanol by / alcohol dehydrogenase?
vasodilator - increases cGMP to induce smooth muscle relaxation (arterioles>veins; afterload reduction)
- Acetaldehyde - Nausea - vomiting - headache - & hypotension
- Tetracycline
1) Hypersensitivity reactions 2) Increased nephrotoxicity of Aminoglycosides 3) Disulfiram - like reaction with ethanol (those with a methylthiotetrazole group - e.g. - cefamandole)

2. What is the MOA of Imipenem?
Prevents release of mediators from mast cells. Effective only for the prophylaxis of asthma. Not effective during an acute attack.
Digitoxin>95% Digoxin 75%
Acts as a wide spectrum carbapenem
Beta1 more than B2

3. What enzymes are inhibited by NSAIDs - acetaminophen and COX II inhibitors?
Cyclooxygenases (COX I - COX II).
Albuterol - tertbutaline
effective in torsade de pointes and digoxin toxicity
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine

4. Aztreonam ________ to penicillinase
is resistant
Alpha -1 antagonist
GI upset
Extended spectrum penicillin: certain Gram + bacteria and Gram - rods

5. Why are albuterol and terbutaline effective in tx of acute asthmatic attacks?
It must be Phosphorylated by Viral Thymidine Kinase
These B-2 agonists cause respiratory smooth muscle to relax.
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
Phenothiazine (neuroleptic - antiemetic).

6. Why are Methicillin - Nafcillin - and Dicloxacillin penicillinase resistant?
- Infections - Trauma - Seizures - CO - Overdose - Metabolic - Alcohol (IT'S COMA)
Due to the presence of a bulkier R group
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia
- aminoglycosides - loop diuretics - cisplatin

7. ADH antagonists - site of action?
sedation - sleep alterations
collecting ducts
- Cimetidine - ketoconazole - grapefruit juice - erythromycin - INH - sulfonamides
K+ wasting - metabolic alkalosis - hypotension - ototoxicity

8. List the mechanism - clinical use - & toxicity of Bleomycin.
Does not cross
- DNA intercalator - testicular & lymphomas - Pulmonary fibrosis mild myelosuppression.
Activates cholinergic receptors on bladder and bowel smooth muscle - alleviating post - op and neurogenic ileus and urinary retention.
Amphetamine and Ephedrine

9. Why would you give a drug like pancuronium or succinylcholine?
Useful in muscle paralysis during surgery or mechanical ventilation.
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.
Mg = Must go to the bathroom.
- Acetaldehyde - Nausea - vomiting - headache - & hypotension

10. Resistance mechanisms for Chloramphenicol
1) Hypersensitivity reactions 2) Increased nephrotoxicity of Aminoglycosides 3) Disulfiram - like reaction with ethanol (those with a methylthiotetrazole group - e.g. - cefamandole)
hyperaldosteronism - K+ depletion - CHF
not a sulfonamide - but action is the same as furosemide
Modification via Acetylation

11. What are five disadvantages of Oral Contraceptives (synthetic progestins - estrogen)?
Intrathecally
1. Taken daily 2. No protection against STDs 3. Raises triglycerides 4. Depression - weight gain - nausea - HTN 5. Hypercoagulable state
local anesthetic. CNS stimulation or depression. CV depression.
Blocks Influenza A and RubellA; causes problems with the cerebellA

12. Hydrochlorothiazide - toxicity? (hyperGLUC - plus others)
penicillinase resistant
Flecainide - Encainide - Propafenone
impotence - exacerbation of asthma - CV effects - CNS effects - may mask hypoclycemia
Hypokalemic metabolic alkalosis - hyponatremia - hyperGlycemia - hyperLipidemia - hyperUricemia - hyperCalcemia - sulfa allergy.

13. List some specifics of lead poisoning(4)?
Imipenem
- A57Blue lines in gingiva & long bones - Encephalopathy & Foot drop - Abdominal colic / - Sideroblastic anemia
anuria - CHF
- S- phase anti - metabolite Pyr analogue - Colon - solid tumors - & BCC/ - Irreversible myelosuppression

14. What is the category of drug names ending in - ane (e.g. Halothane)
Inhalational general anesthetic.
Ceftriaxone
Blocks Influenza A and RubellA; causes problems with the cerebellA
No - hemicholinum block the uptake of Choline and thus Ach synthesis

15. What is the category - desired effect - and adverse effect of Isoproterenol in the treatment of Asthma?
Dermatophytes (tinea - ringworm)
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.
Nonspecific beta - agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Adverse effect is tachycardia (Beta 1).
physostigmine

16. What is the mechanism of action and clinical use of the antiandrogen Flutamide?
Yes
Flutamide is a nonsteroidal competitive inhibitor of androgens at the testosterone receptor - used in prostate carcinoma.
torsade de pointes - excessive Beta block
amphetamine and ephedrine

17. Name the common Non - Nucleoside Reverse Transcriptase Inhibitors
block Na+ channels in the cortical collecting tubule
Nevirapine - Delavirdine
CMV Retinitis in IC pts When Ganciclovir fails
No - hemicholinum block the uptake of Choline and thus Ach synthesis

18. Which drug(s) cause this reaction: Atropine - like side effects?
Malaria (P. falciparum)
- Tricyclic antidepressants
sedation - depression - nasal stuffiness - diarrhea
torsade de pointes - excessive Beta block

19. Describe first - order kinetics?
Staphlococcus aureus and Clostridium difficile (pseudomembranous colitis)
Constant FRACTION eliminated per unit time.(exponential)
Interstitial nephritis
Flutamide is a nonsteroidal competitive inhibitor of androgens at the testosterone receptor - used in prostate carcinoma.

20. Which drug(s) cause this reaction: Cough?
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.
- ACE inhibitors (Losartan>no cough)
scopolamine
BM suppression (neutropenia - anemia) - Peripheral neuropathy

21. Which RT inhibitors cause a Rash?
Hypokalemic metabolic alkalosis - hyponatremia - hyperGlycemia - hyperLipidemia - hyperUricemia - hyperCalcemia - sulfa allergy.
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine
Non - Nucleosides
Flecainide - Encainide - Propafenone

22. Why would a patient with cog - wheel rigidity and a shuffling gait be given benztropine?
Penicillin.
1. Infertility (pulsatile) 2. Prostate cancer (continuous: use with flutamide) 3. Uterine fibroids
Parkinson patients benefit from antimuscarinic agents through its inhibitory action within the indirect pathway.
Prevention of NSAID- induced peptic ulcers - maintains a PDA.

23. When is HIV therapy initiated?
When pts have Low CD4+ (< 500 cells/cubic mm) or a High Viral Load
Norepinephrine
- Alkalating agents+cisplatin - Doxorubicin+Dactinomycin - Bleomycin - Etoposide
Decreased uptake or Increased transport out of cell

24. For Heparin What is the Lab value to monitor
aPTT (intrinsic pathway)
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.
Polymyxin B - Polymyxin E
Onchocerciasis ('river blindness'-- rIVER- mectin)

25. Which drug(s) cause this reaction: Oto and Nephrotoxicity (3)?
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs
- Upper respiratory tract infections - pneumonias - STDs: Gram+ cocci (streptococcal infect in pts allergic to penicillin) - Mycoplasma - Legionella - Chlamydia - Neisseria
Verapamil - Diltiazem - Bepridil
- aminoglycosides - loop diuretics - cisplatin

26. What is the MOA for the Azoles?
Inhibit Ergosterol synthesis
Interstitial nephritis
- Act on same receptor - Full has greater efficacy
Local anesthetic.

27. Which drug(s) cause this reaction: Cutaneous flushing (4)?
- Niacin - Ca++ channel blockers - adenosine - vancomycin
Oral
Inhibits CMV DNA polymerase
Prevents the release of calcium from the sarcoplasmic reticulum of skeletal muscle.

28. List the specific antidote for this toxin: Benzodiazepines
Increased systolic and pulse pressure - decreased diastolic pressure - and little change in mean pressure.
- Flumazenil
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.
- Bleomycin - amiodarone - busulfan

29. How can Isoniazid (INH)- induced neurotoxicity be prevented?
- Oral Contraceptives
H2 antagonist
Pyridoxine (B6) administration
Norepinephrine

30. Which drug(s) cause this reaction: Focal to massive hepatic necrosis (4)?
- Halothane - Valproic acid - acetaminophen - Amantia phalloides
- Methylene blue
Receptors = D1=D2>beta>alpha - thus increasing heart rate (beta) and blood pressure (alpha vasoconstriction) while maintaining kidney perfusion (dopamine receptors)
- N- acetylcystine

31. What are four Sulfonylureas?
- Halothane - Valproic acid - acetaminophen - Amantia phalloides
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide
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
Corticosteroids; prevent production of leukotrienes from arachodonic acid by blocking phospholipase A2. Drugs of choice in a patient with status asthmaticus (in combination with albuterol.)

32. Which drug(s) cause this reaction: G6PD hemolysis(8)?
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol
- ED 50 is less than the Km (less than 50% of receptors)
Impairs the synthesis of vitamin K- dependent clotting factors
- B51Naloxone / naltrexone (Narcan)

33. List the mechanism - clinical use - & toxicity of Paclitaxel.
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.
- DNA intercalator - Hodgkin's - myeloma - sarcoma - and solid tumors - Cardiotoxicity & alopecia
- Steroids - Tamoxifen
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.

34. Are penicillinase resistant
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine
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
Tricyclic antidepressant.
Methicillin - Nafcillin - and Dicloxacillin

35. How are Interferons (INF) used clinically?

36. Which drug(s) cause this reaction: Tubulointerstitial Nephritis (5)?
1. Meningococcal carrier state 2. Chemoprophylaxis in contacts of children with H. influenzae type B
Alpha -1 antagonist
Nephrotoxicity
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)

37. Resistance mechanisms for Vancomycin
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
local anesthetic. CNS stimulation or depression. CV depression.
- B51Naloxone / naltrexone (Narcan)

38. What is the category of drug names ending in - terol (e.g. Albuterol)
H2 antagonist
- Oxalic acid - Acidosis & nephrotoxicity
Beta -2 agonist.
1. Meningococcal carrier state 2. Chemoprophylaxis in contacts of children with H. influenzae type B

39. What beta 2 agonist will help your 21yo Astma pt?
narcolepsy - obesity - and attention deficit disorder (I wouldn't recommend this)
Antifungal.
Theoretically it could be used to block the cephalic phase of acid secretion (vagal stimulation).
Albuterol - tertbutaline

40. Antimicrobial prophylaxis for PCP
Ibuprofen - Naproxen - and Indomethacin
Polymyxin B - Polymyxin E
TMP- SMZ (DOC) - aerosolized pentamidine
Phenothiazine (neuroleptic - antiemetic).

41. Mannitol - site of action?
1. RNA pol inhibitor 2. Revs up P450 3. Red/orange body fluids 4. Rapid resistance if used alone
proximal convoluted tubule - thin descending limb - and collecting duct
PT
Acetaminophen has antipyretic and analgesic properties - but lacks anti - inflammatory properties.

42. Which drug(s) cause this reaction: Fanconi's syndrome?
- Tetracycline
Blood
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens

43. Why does atropine dilate the pupil?
Primaquine
Verapamil - Diltiazem - Bepridil
Blocking muscarinic receptors in the circular fibers of the eye - results in unopposed action of radial muscles to dilate.
GI intolerance (nausea - diarrhea) - Hyperglycemia - Lipid abnormalities - Thrombocytopenia (Indinavir)

44. What are the side effects of Polymyxins?
proarrhythmic
narcolepsy - obesity - and attention deficit disorder (I wouldn't recommend this)
Neurotoxicity - Acute renal tubular necrosis
Triple Therapy' 2 Nucleoside RT Inhibitors with a Protease Inhibitor

45. What is the category of drug names ending in - barbital (e.g. Phenobarbital)
Babiturate.
- Cimetidine - ketoconazole - grapefruit juice - erythromycin - INH - sulfonamides
loop diuretics - spironolactone
Inhibits reabsorption of uric acid.

46. Toxic side effects of the Azoles?
Norepinephrine (Alpha1 -2 and beta 1)
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis
Hormone synthesis inhibition (Gynecomastia) - Liver dysfunction (Inhibits CYP450) - Fever - Chills
- Hypersensitivity reactions - Hemolysis - Nephrotoxicity (tubulointerstitial nephritis) - Kernicterus in infants Displace other drugs from albumin (e.g. - warfarin)

47. Cocaine casues vasoconstriction and local anesthesia by What mechanism
- Dimercaprol - succimer
Suramin
Indirect agonist - uptake inhibitor
Interstitial nephritis

48. What is Ketoconazole specifically used for?
Blastomyces - Coccidioides - Histoplasma - C. albicans; Hypercortisolism
Decreases synthesis of Mycolic Acid
- Cloazapine - carbamazapine - colchicine - PTU
Ceftriaxone

49. If a patient is given hexamethonium - What would happen to his/her heart rate?
- Atropine & pralidoxime
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.
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time
Digitoxin 168hrs Digoxin 40 hrs

50. Acetazolamide - mechanism?
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.
Depolymerizes microtubules - impairing leukocyte chemotaxis and degranulation.
Ototoxicity - Hypokalemia - Dehydration - Allergy (sulfa) - Nephritis (interstitial) - Gout
Interstitial nephritis