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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. How does a competitive antagonist effect an agonist?
- Shifts the curve to the right - increases Km
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.
Tricyclic antidepressant.
- Isoniazid

2. What are the clinical uses for Ticlopidine - Clopidogrel?
Misoprostol is a PGE1 analog that increases the production and secretion of the gastic mucous barrier.
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)
Methylxanthine.
Acute coronary syndrome; coronary stenting. Decreases the incidence or recurrence of thrombotic stroke.

3. Verapamil has similar action to?
Beta Blockers
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.
Staphlococcus aureus
Beta1 more than B2

4. What is a possible toxicity of Ticlopidine - Clopidogrel usage?
new arrhythmias - hypotension
not a sulfonamide - but action is the same as furosemide
Vibrio cholerae Acne Chlamydia Ureaplasma Urealyticum Mycoplasma pneumoniae Borrelia burgdorferi (Lyme's) Rickettsia Tularemia
Neutropenia (ticlopidine); reserved for those who cannot tolerate aspirin.

5. What are the clinical uses for 3rd Generation Cephalosporins?
The PTT.
Local anesthetic.
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)
hypertension - angina - arrhythmias

6. Resistance mechanisms for Cephalosporins/Penicillins
Beta - lactamase cleavage of Beta - lactam ring
Inhibit RT of HIV and prevent the incorporation of viral genome into the host DNA
- Aminocaproic acid
Aminoglycosides - Tetracyclines

7. List the specific antidote for this toxin: Cyanide
- Nitrate - hydroxocobalamin thiosulfate
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow
1.Gram - rods of the Urinary and GI tracts (including Pseudomonas) 2.Neisseria 3. Some Gram + organisms
Slow - limited by half lives of clotting factors

8. What are Aminoglycosides used for clinically?
fetal renal damage - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
Severe Gram - rod infections.
Neutropenia
Useful in muscle paralysis during surgery or mechanical ventilation.

9. Common toxicities associated with Griseofulvin?
Teratogenic - Carcinogenic - Confusion - Headaches
Amphetamine and Ephedrine
collecting ducts
Penicillin - V

10. What is the clinical use for Warfarin?
Chronic anticoagulation.
Sildenafil fills the penis
Prefers beta's at low doses - but at higher doses alpha agonist effects are predominantly seen.
Doxycycline - because it is fecally eliminated

11. Common side effects associated with Clindamycin include?
Pseudomembranous colitis (C. difficile) - fever - diarrhea
BM suppression (neutropenia - anemia) - Peripheral neuropathy
hypertension - CHF - diabetic renal disease
Paranteral (IV - SC)

12. What is the most common cause of Pt noncompliance with Macrolides?
GI discomfort
Large anionic polymer - acidic
dizziness - flushing - constipation (verapamil) - nausea
- Steroids - Tamoxifen

13. List the specific antidote for this toxin: Anticholinesterases (organophosphate.)
Antimetabolite derivative of 6- mercaptopurine that interferes with the metablolism and synthesis of nucleic acid.
- Atropine & pralidoxime
bradycardia - AV block - CHF
Beta adrenergic receptors and Ca2+ channels (stimulatory)

14. What are the nondepolarizing neuromuscular blocking drugs?
Tubocurarine - atracurium - mivacurium - pancuronium - vecuronium - rapacuronium
NO AP duration effect. useful in V- tach that progresses to V- fib and in intractable SVT Last RESORT
Pseudomembranous colitis (C. difficile) - fever - diarrhea
- Haloperidol - chlorpromazine - reserpine - MPTP

15. What is Metronidazole used for clinically?
Hypokalemic metabolic alkalosis - hyponatremia - hyperGlycemia - hyperLipidemia - hyperUricemia - hyperCalcemia - sulfa allergy.
edrophonium (extremely short acting anticholinesterase)
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium
AmOxicillin has greater Oral bioavailability

16. What is the MOA for Carbenicillin - Piperacillin - and Ticarcillin?
Parkinson patients benefit from antimuscarinic agents through its inhibitory action within the indirect pathway.
Buy AT 30 - CELL at 50'
Same as penicillin. Extended spectrum antibiotics
- aminoglycosides - loop diuretics - cisplatin

17. Antimicrobial prophylaxis for Gonorrhea
increase AP duration - increase ERP - increase QT interval - for use When other arrhythmics fail
Primaquine
Cyclooxygenases (COX I - COX II).
Ceftriaxone

18. What is the major toxic side effect of Penicillin?
fetal renal toxicity - hyperkalemia
Hypersensitivity reactions
Gram + cocci - Gram - rods - and Anerobes
cholestyramine - colestipol

19. K+- clinical use?
depresses ectopic pacemakers - especially in digoxin toxicity
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.
impotence - exacerbation of asthma - CV effects - CNS effects - may mask hypoclycemia
VACUUM your Bed Room'

20. Furosemide - toxicity? (OH DANG)
Ototoxicity - Hypokalemia - Dehydration - Allergy (sulfa) - Nephritis (interstitial) - Gout
- partial agonist can have increased - decreased - /A21or equal potency as full agonist. - Potency is an independent factor.
amphetamine and ephedrine
- Fluoroquinolones

21. The MOA for Chloramphenicol is?
GI upset - Superinfections - Skin rashes - Headache - Dizziness
- Shifts the curve to the right - increases Km
Inhibition of 50S peptidyl transferase - Bacteriostatic
Protamine Sulfate is used for rapid reversal of heparinization (positively charged molecule that binds to negatively charged heparin).

22. What are two clinical uses of Azathioprine?
Methylation of rRNA near Erythromycin's ribosome binding site
The PTT.
- S- phase anti - metabolite folate analogue - Luk - Lymp - sarc - RA - & psoriasis / - Reversible myelosuppression
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)

23. Which drug(s) cause this reaction: Neuro and Nephrotoxic?
Digoxin=urinary Digitoxin=biliary
alpha -1 > alpha -2; used as a pupil dilator - vasoconstrictor - and for nasal decongestion
- polymyxins
Polymyxins

24. How would you reverse the effect of a neuromuscular blocking agent?
Benzodiazepine.
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.
Give an antichloinesterase - neostigmine - edrophonium - etc
blocks SR Ca2+ channels

25. What is the MOA of Polymyxins?
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.
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents
Only in limited amounts
- inhibits HGPRT (pur. Syn.) - Luk - Lymph

26. What are the side effects of Polymyxins?
Neurotoxicity - Acute renal tubular necrosis
With an amino acid change of D- ala D- ala to D- ala D- lac
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia
Inhibits bacterial Dihydrofolate Reductase - Bacteriostatic

27. Hydrochlorothiazide - toxicity? (hyperGLUC - plus others)
- inhibits HGPRT (pur. Syn.) - Luk - Lymph
fetal renal damage - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
Hypokalemic metabolic alkalosis - hyponatremia - hyperGlycemia - hyperLipidemia - hyperUricemia - hyperCalcemia - sulfa allergy.
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)

28. What side effect of using atropine to induce pupillary dilation would you expect?
Atropine would also block the receptors in the ciliary muscle - causing an impairment in accommodation (cycloplegia).
Interferes with microtubule function - disrupts mitosis - inhibits growth
Binds to the Pyrophosphate Binding Site of the enzyme
viral kinase

29. What are the major toxic side effects of the Cephalosporins?
Same as penicillin. Act as narrow spectrum antibiotics
- S- phase anti - metabolite Pyr analogue - Colon - solid tumors - & BCC/ - Irreversible myelosuppression
Systemic mycoses
1) Hypersensitivity reactions 2) Increased nephrotoxicity of Aminoglycosides 3) Disulfiram - like reaction with ethanol (those with a methylthiotetrazole group - e.g. - cefamandole)

30. What is Metronidazole combined with for 'triple therapy'? Against What organism?
Systemic mycoses
Atropine would also block the receptors in the ciliary muscle - causing an impairment in accommodation (cycloplegia).
Well tolerated in general but occasionally - Nephrotoxicity - Ototoxicity - Thrombophlebitis - diffuse flushing='Red Man Syndrome'
Bismuth and Amoxicillin or Tetracycline; against Helobacter pylori

31. What is the clinical use of Tacrolimus (FK506)?
ACE inhibitor.
- Dimercaprol - succimer
severe orthostatic hypotension - blurred vision - constipation - sexual dysfunction
Potent immunosuppressive used in organ transplant recipients.

32. Which drug(s) cause this reaction: Gray baby syndrome?
- Chloramphenicol
viral kinase
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic
cholestyramine - colestipol

33. How do the Protease Inhibitors work?
Megaloblastic anemia - Leukopenia - Granulocytopenia
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention
viral kinase
Inhibt Assembly of new virus by Blocking Protease Enzyme

34. What is the category of drug names ending in - tropin (e.g. Somatotropin)
Pituitary hormone.
- Corticosteroids - heparin
Severe Gram - rod infections.
scopolamine

35. Which H2 Blocker has the most toxic effects and What are they?
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.
Directly of indirectly aid conversion of plasminogen to plasmin Which cleaves thrombin and fibrin clots. (It is claimed that tPA specifically converts fibrin - bound plasminogen to plasmin.)
collecting ducts
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain

36. What are the side effects of Rifampin?
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.
Prevents the release of calcium from the sarcoplasmic reticulum of skeletal muscle.
Inhibit RT of HIV and prevent the incorporation of viral genome into the host DNA
Minor hepatotoxicity - Drug interactions (activates P450)

37. Why does atropine dilate the pupil?
proximal convoluted tubule
1. Kidney transplantation 2. Autoimmune disorders (including glomerulonephritis and hemolytic anemia)
Blocking muscarinic receptors in the circular fibers of the eye - results in unopposed action of radial muscles to dilate.
decrease AP duration - affects ischemic or depolarized Purkinje and ventricular system

38. Do Tetracyclines penetrate the CNS?
Only in limited amounts
Blocks viral penetration/uncoating; may act to buffer the pH of the endosome
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.
- Ethosuxamide - sulfonamides - lamotrigine

39. What are five toxicities associated with Tacrolimus (FK506)?
hypertension - angina - arrhythmias
No. Atropine is used to reduce urgency in mild cystitis. So it would aggravate the urinary retention.
Polymyxin B - Polymyxin E
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.

40. What is the mechanism of action of Probenacid used to treat chronic gout?
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
Inhibits reabsorption of uric acid.
GI intolerance (nausea - diarrhea) - Hyperglycemia - Lipid abnormalities - Thrombocytopenia (Indinavir)
1)Binds penicillin - binding proteins 2) Blocks transpeptidase cross - linking of cell wall 3) Activates autolytic enzymes

41. What type of gout is treated with Allopurinol?
SLUD (salivation - Lacrimation - urination - Defecation)as well as airway secretion - GI motility - acid secretions
Chronic gout.
Prevents the release of ACh - Which results in muscle paralysis.
1. Phospholipase A2 is prevented from releasing arachidonic acid 2. Decreases protein synthesis thus lowering amount of Cyclooxygenase enzymes

42. Which drug(s) cause this reaction: Hepatitis?
Beta - lactamase cleavage of Beta - lactam ring
Prevention of NSAID- induced peptic ulcers - maintains a PDA.
- Isoniazid
Pentamidine

43. What is the mechanism of action of the glucocorticoids?
blocks SR Ca2+ channels
Dopamine; causes its release from intact nerve terminals
hypertension - angina - arrhythmias
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.

44. Antimicrobial prophylaxis for Syphilis
Benzathine penicillin G
Dermatophytes (tinea - ringworm)
Aminoglycosides
In 4 half - lifes= (94%) T1/2 = (0.7x Vd)/CL

45. Nifedipine has similar action to?
- Acetaldehyde - Nausea - vomiting - headache - & hypotension
Nitrates
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.
Protease Inhibitors and Reverse Transcriptase Inhibitors

46. What is the major side effect for Ampicillin and Amoxicillin?
Epinephirine(Alpha1 -2 and Beta 1 -2)
Hypersensitivity reactions
thick ascending limb
Nephrotoxicity (esp. with Cephalosporins) - Ototoxicity (esp. with Loop Diuretics)

47. Which diuretics increase urine K+?
all except the K+ sparing diuretics Spironolactone - Triamterene - Amiloride
Praziquantel
Inhibits cell wall mucopeptide formation - Bactericidal
Those patients who are taking nitrates.

48. What is the MOA of Aztreonam?
local anesthetic. CNS stimulation or depression. CV depression.
Parkinson patients benefit from antimuscarinic agents through its inhibitory action within the indirect pathway.
Inhibits cell wall synthesis ( binds to PBP3). A monobactam
Rapid (seconds)

49. Norepi feedbacks and inhibits the presynaptic receptor by What mechanism
Binding to the presynaptic alpha 2 release modulating receptors
- MT polymerization inhibitor(M phase) - MOPP - lymphoma - Willm's & choriocarcinoma - neurotoxicity and myelosuppression
TMP- SMZ
- Chloramphenicol - benzene - NSAIDS - PTU - phenytoin

50. Name two classes of drugs for HIV 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
It must be Phosphorylated by Viral Thymidine Kinase
- Glucagon
Protease Inhibitors and Reverse Transcriptase Inhibitors