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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. Which drug(s) cause this reaction: Anaphylaxis?
depresses ectopic pacemakers - especially in digoxin toxicity
compensatory tachycardia - fluid retention - lupus - like syndrome
- Penicillin
Depolymerizes microtubules - impairing leukocyte chemotaxis and degranulation.

2. Which drug(s) cause this reaction: Gynecomastia (6)?
1. Meningococcal carrier state 2. Chemoprophylaxis in contacts of children with H. influenzae type B
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.

3. What are two toxicities associated with Cyclosporine?
1. Predisposes to viral infections and lymphoma 2. Nephrotoxic (preventable with mannitol diuresis)
Atropine would also block the receptors in the ciliary muscle - causing an impairment in accommodation (cycloplegia).
Vibrio cholerae Acne Chlamydia Ureaplasma Urealyticum Mycoplasma pneumoniae Borrelia burgdorferi (Lyme's) Rickettsia Tularemia
Phase 1 = prolonged depolarization - no antidote - effect potentiated by anticholinesterase; Phase 2 = repolarized but blocked - an anticholinesterase is the antidote for this phase.

4. What are Aminoglycosides synergistic with?
Succinylcholine
Beta - lactam antibiotics
Nitrates
local anesthetic. CNS stimulation or depression. CV depression.

5. What is the mechanism of action of Cyclosporine?
Digitoxin 168hrs Digoxin 40 hrs
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol
Liver
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.

6. Which drug(s) cause this reaction: Diabetes insipidus?
sedation - depression - nasal stuffiness - diarrhea
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.)
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity
- Lithium

7. List the specific antidote for this toxin: Amphetamine
INH: Injures Neurons and Hepatocytes
- Ammonium Chloride
Penicillin - V
Norepinephrine

8. What type of patient should not take Misoprostol and why?
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain
AZT
blocking the beta adrenergic receptor leads to decreased cAMP - and decreased Ca2+ flux
Misoprostol is contraindicated in women of childbearing potential because it is an abortifacient.

9. List the mechanism - clinical use - & toxicity of Cisplatin.
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.
- Alkalating agent - testicular - bladder - ovary -& lung - Nephrotoxicity & CN VIII damage.
They inhibit reuptake of NE at the nerve terminal (as does cocaine).
No - it inhibits the release of Nor Epi

10. What is the formula for Volume of distribution (Vd)
With supplemental Folic Acid
- Constant AMOUNT eliminated per unit time. - Etoh & ASA
Tricyclic antidepressant.
Vd= (Amt. of drug in body/ Plasma drug conc.)

11. What is the category of drug names ending in - navir (e.g. Saquinavir)
Protease inhibitor.
Interferes with microtubule function - disrupts mitosis - inhibits growth
Penicillin - G
Cilastatin

12. What is a prerequisite for Acyclovir activation?
Pretreat with antihistamines and a slow infusion rate
It must be Phosphorylated by Viral Thymidine Kinase
Activates cholinergic receptors on bladder and bowel smooth muscle - alleviating post - op and neurogenic ileus and urinary retention.
Quinidine - Amiodarone - Procainamide - Disopyramide

13. What is the memory key for the effect of magnesium hydroxide overuse?
Inhibits cGMP phosphodiesterase - casuing increased cGMP - smooth muscle relaxation in the corpus cavernosum - increased blood flow - and penile erection.
Mg = Must go to the bathroom.
Bactericidal for: Gram + rod and cocci - Gram - cocci - and Spirochetes
Digitoxin>95% Digoxin 75%

14. What is the MOA of the RT Inhibitors?
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs
Inhibit RT of HIV and prevent the incorporation of viral genome into the host DNA
GI side effects. (Indomethacin is less toxic - more commonly used.)
Neutropenia (ticlopidine); reserved for those who cannot tolerate aspirin.

15. How is Amphotericin B administered for fungal meningitis?
Intrathecally
In 4 half - lifes= (94%) T1/2 = (0.7x Vd)/CL
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.
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.

16. What is the memory aid for subunit distribution of ribosomal inhibitors?

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17. Name three calcium channel blockers?
Imipenem
Nifedipine - Verapamil - Diltiazem
AZT
- Antipsychotics

18. What is Metronidazole combined with for 'triple therapy'? Against What organism?
Inhibit viral DNA polymerase
Bismuth and Amoxicillin or Tetracycline; against Helobacter pylori
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic
- Vitamin K & fresh frozen plasma

19. Which drug(s) cause this reaction: Tubulointerstitial Nephritis (5)?
1. RNA pol inhibitor 2. Revs up P450 3. Red/orange body fluids 4. Rapid resistance if used alone
Blastomyces - Coccidioides - Histoplasma - C. albicans; Hypercortisolism
Inhibits DNA dependent RNA polymerase
- Sulfonamides - furosemide - methicillin - rifampin - NSAIDS (ex. ASA)

20. For Warfarin What is the Onset of action
Hypersensitivity reactions
Slow - limited by half lives of clotting factors
- EDTA - dimercaprol - succimer - & penicillamine
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic

21. What is the mechanism of action of the Sulfonylureas?
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.
Yes
Botulinum
thiazides - amiloride

22. Why is reserpine effective in treating HTN?
In 4 half - lifes= (94%) T1/2 = (0.7x Vd)/CL
Reserpine inhibits dopamine transport into vesicles - attenuating its conversion to NE by dopamine beta - hydroxylase.
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).
block voltage dependent L- type Ca2+ channels of cardiac and smooth muscle - decreasing contractility

23. Which drug(s) cause this reaction: Agranulocytosis (3)?
Flutamide is a nonsteroidal competitive inhibitor of androgens at the testosterone receptor - used in prostate carcinoma.
- Cloazapine - carbamazapine - colchicine - PTU
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
Delirium - Tremor - Nephrotoxicity

24. What are the clinical indications for bethanechol?
1. Weight gain 2. Hepatotoxicity (troglitazone)
Activates cholinergic receptors on bladder and bowel smooth muscle - alleviating post - op and neurogenic ileus and urinary retention.
competitive inhibirot of aldosterone in the cortical collecting tubule
1. Taken daily 2. No protection against STDs 3. Raises triglycerides 4. Depression - weight gain - nausea - HTN 5. Hypercoagulable state

25. What are Aminoglycosides used for clinically?
Severe Gram - rod infections.
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.
Inhibition of 50S peptidyl transferase - Bacteriostatic
- Airway - Breathing - Circulation - Dextrose (thiamine & narcan) - ABCD

26. What is the mecanism of action - effective period - and ineffective period of use for Cromolyn in treating Asthma?
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
Gram + cocci - Haemophilus influenza - Enterobacter aerogenes - Neisseria species - P. mirabilis - E. coli - K. pneumoniae - Serratia marcescens ( HEN PEcKS )
Prevents release of mediators from mast cells. Effective only for the prophylaxis of asthma. Not effective during an acute attack.
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium

27. Preferential action of the Ca2+ channel blockers at cardiac muscle?
Binding to the presynaptic alpha 2 release modulating receptors
K+ wasting - metabolic alkalosis - hypotension - ototoxicity
cardiac muscle: Verapamil>Diltiazem>Nifedipine
Phosphorylation by a Viral Kinase

28. What is a possible toxicity of Alpha - glucosidase inhibitors used in type -2 diabetes?
GI disturbances.
Suramin
1)Binds penicillin - binding proteins 2) Blocks transpeptidase cross - linking of cell wall 3) Activates autolytic enzymes
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.

29. Which drug(s) cause this reaction: Disulfram - like reaction (4) ?
- Act on same receptor - Full has greater efficacy
Botulinum
- Lithium
- Metronidazole - certain cephalosporins - procarbazine - sulfonylureas

30. What drug is given for Pneumocystis carinii prophylaxis?
Inhibit steroid synthesis - used in the treatment of polycystic ovarian syndrome to prevent hirsutism.
Digitoxin 70% Digoxin 20-40%
Pentamidine
- ED 50 is less than the Km (less than 50% of receptors)

31. Adverse effects of Nifedipine - verapamil?
dizziness - flushing - constipation (verapamil) - nausea
Lipoxygenase
Babiturate.
Resistant Gram - infections

32. What are five toxicities associated with Tacrolimus (FK506)?
blocks SR Ca2+ channels
Reserpine inhibits dopamine transport into vesicles - attenuating its conversion to NE by dopamine beta - hydroxylase.
Sucralfate cannot work in the presence of antacids or H2 blockers because it requires an acidic environment to polymerize.
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.

33. Adverse effects of Captopril?
- Oxalic acid - Acidosis & nephrotoxicity
Parkinson patients benefit from antimuscarinic agents through its inhibitory action within the indirect pathway.
fetal renal toxicity - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
Ipratropium

34. Clonidine is the preferred sym pathomimetic tx of HTN in pts with renal disease - why??
Reversible block of histamine H2 receptors
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow
Modification via Acetylation - Adenylation - or Phosphorylation
- Quinidine - quinine

35. Which drug(s) cause this reaction: G6PD hemolysis(8)?
physostigmine
- Sulfonamides - INH - ASA - Ibuprofen - primaquine - nitrofurantoin /- pyrimethamine - chloramphenicol
The PTT.
Norepinephrine (Alpha1 -2 and beta 1)

36. For Warfarin What is the Structure
- Bleomycin - amiodarone - busulfan
Small lipid - soluble molecule
Acetylcholine esterase
Megaloblastic anemia - Leukopenia - Granulocytopenia

37. What is the mechanism of action of Sildenafil (Viagra)?
- ACE inhibitors (Losartan>no cough)
Reversibly inhibit cyclooxygenase (COX I and COX II). Block prostaglandin synthesis.
Inhibits cGMP phosphodiesterase - casuing increased cGMP - smooth muscle relaxation in the corpus cavernosum - increased blood flow - and penile erection.
1. Hypoglycemia (more common with 2nd - generation drugs: glyburide - glipizide) 2. Disulfiram - like effects (not seen with 2nd - generation drugs).

38. What is the MOA for Carbenicillin - Piperacillin - and Ticarcillin?
G6PD deficient individuals
Same as penicillin. Extended spectrum antibiotics
Parkinson patients benefit from antimuscarinic agents through its inhibitory action within the indirect pathway.
HSV - VZV - EBV - Mucocutaneous and Genital Herpes Lesions - Prophylaxis in Immunocompromised pts

39. Secretion of What drug is inhibited by Probenacid used to treat chronic gout?
Penicillin.
Indirect agonist - uptake inhibitor
Teratogenic - Carcinogenic - Confusion - Headaches
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic

40. What are four thrombolytics?
1. Streptokinase 2. Urokinase 3. tPA (alteplase) - APSAC (anistreplase)
Ld= (CpxVd)/F Cp=plasma conc. F= Bioaval.
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)

41. What is the MOA for Trimethoprim (TMP)?
1. Better bioavailability 2. 2 to 4 times longer half life 3. Can be administered subcutaneously 4. Does not require laboratory monitoring
hypertension - angina - arrhythmias
The only local anesthetic with vasoconstrictive properties.
Inhibits bacterial Dihydrofolate Reductase - Bacteriostatic

42. What are three complications of Warfarin usage?
1. Bleeding 2. Teratogenicity 3. Drug - drug interactions
Hydralazine and Minoxidil
Bethanechol - Neostigmine - physostigmine
Polymyxin B - Polymyxin E

43. What are the clinical uses for Imipenem/cilastatin?
1. Acarbose 2. Miglitol
INH: Injures Neurons and Hepatocytes
proximal convoluted tubule
Gram + cocci - Gram - rods - and Anerobes

44. MOA: Block protein synthesis at 30s subunit
Aminoglycosides - Tetracyclines
Inhibits reabsorption of uric acid.
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.
Bethanechol - Neostigmine - physostigmine

45. What are the clinical uses for 1st Generation Cephalosporins?
Gram + cocci - Proteus mirabilis - E. coli - Klebsiella pneumoniae (PEcK)
- Cloazapine - carbamazapine - colchicine - PTU
Forms toxic metabolites in the bacterial cell - Bactericidal
Vibrio cholerae Acne Chlamydia Ureaplasma Urealyticum Mycoplasma pneumoniae Borrelia burgdorferi (Lyme's) Rickettsia Tularemia

46. A common side effects of Interferon (INF) treatment is?
Neutropenia
Pituitary hormone.
Dobutamine has more of an affintiy for beta -1 than beta -2 - and is used for treating heart failure and shock. Albuterol and terbutaline is the reverse - and is used in treatment of acute asthma.
Methylzanthine; desired effect is bronchodilation - may cause bronchodilation by inhibiting phosphodiesterase - enzyme involved in degrading cAMP (controversial).

47. List the specific antidote for this toxin: Antimuscarinic (anticholinergic)
- Physostigmine salicylate
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.
1. Hydrocortisone 2. Predisone 3. Triamcinolone 4. Dexamethasone 5. Beclomethasone
Keratin containing tissues - e.g. - nails

48. Describe Phase II metabolism in liver(3)?
Nephrotoxicity
- acetylation - glucuron. - & sulfation - Conjugation - Polar product
Doxycycline - because it is fecally eliminated
Delirium - Tremor - Nephrotoxicity

49. What microorganisms is Aztreonam not effective against?
Dopamine
reversible SLE- like syndrome
Gram + and Anerobes
VACUUM your Bed Room'

50. What antimuscarinic agent is used in asthma and COPD?
Ipratropium
compensatory tachycardia - fluid retention - lupus - like syndrome
Na/K ATPase
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.