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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 neurotransmitter does Amantadine affect? How does it influence this NT?
Dopamine; causes its release from intact nerve terminals
- Daunorubicin & Doxorubicin
- ED 50 is less than the Km (less than 50% of receptors)
Enterobacter

2. What is the mecanism of action - effective period - and ineffective period of use for Cromolyn in treating Asthma?
Prevents release of mediators from mast cells. Effective only for the prophylaxis of asthma. Not effective during an acute attack.
- Alkalate DNA - Brain tumors - CNS toxicity
PT
Flutamide is a nonsteroidal competitive inhibitor of androgens at the testosterone receptor - used in prostate carcinoma.

3. What type of gout is treated with Allopurinol?
Chronic gout.
amphetamine and ephedrine
Nephrotoxicity
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.

4. How is Amphotericin B used clinically?
Rifampin (DOC) - minocycline
- Shifts the curve to the right - increases Km
Wide spectrum of systemic mycoses: Cryptococcus - Blastomyces - Coccidioides - Aspergillus - Histoplasma - Candida - Mucor
Antileukotriene; blocks synthesis by lipoxygenase.

5. Acetazolamide - mechanism?
Doxycycline - because it is fecally eliminated
Similar to cyclosporine; binds to FK- binding protein - inhibiting secretion of IL-2 and other cytokines.
- S- phase anti - metabolite folate analogue - Luk - Lymp - sarc - RA - & psoriasis / - Reversible myelosuppression
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.

6. What are three toxicities of Propylthiouracil?
- Normalize K+ - Lidocaine - & Anti - dig Mab
- Chlorpromazine - thioridazine - haloperidol
- Phenytoin
1. Skin rash 2. Agranulocytosis (rare) 3. Aplastic anemia

7. When is HIV therapy initiated?
Does not cross
Penicillin - Ampicillin - Ticarcillin - Pipercillin - Imipenem - Aztreonam - Cephalosporins
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
When pts have Low CD4+ (< 500 cells/cubic mm) or a High Viral Load

8. For Heparin What is the Lab value to monitor
Delirium - Tremor - Nephrotoxicity
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine
aPTT (intrinsic pathway)

9. Triamterene and amiloride - mechanism?
- Cimetidine - ketoconazole - spironolactone - digitalis - EtOH - estrogens
NO
None. No - because atropine would block the postganglionic muscarinic receptors involved in sweat gland stimulation.
block Na+ channels in the cortical collecting tubule

10. Ibutilide - toxicity?
- Corticosteroids - heparin
Systemic mycoses
torsade de pointes
Antifungal.

11. What is the mechanism of Tacrolimus (FK506)?
Similar to cyclosporine; binds to FK- binding protein - inhibiting secretion of IL-2 and other cytokines.
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
- Chloramphenicol
Staphlococcus aureus and Clostridium difficile (pseudomembranous colitis)

12. Does Heparin have a long - medium - or short half life?
Short.
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity
Gram + and Anerobes
In 4 half - lifes= (94%) T1/2 = (0.7x Vd)/CL

13. ACE inhibitors - mechanism?
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.
- Oral Contraceptives
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium

14. When is Rifampin not used in combination with other drugs?
1. Meningococcal carrier state 2. Chemoprophylaxis in contacts of children with H. influenzae type B
ACIDazolamide' causes acidosis
Severe Gram - rod infections.
Flecainide - Encainide - Propafenone

15. Which drug(s) cause this reaction: P450 inhibition(6)?
- Cimetidine - ketoconazole - grapefruit juice - erythromycin - INH - sulfonamides
Inhibits formation of Initiation Complex - causes misreading of mRNA - Bactericidal
1. Hot flashes 2. Ovarian enlargement 3. Multiple simultaneous pregnancies 4. Visual disturbances
edematous states (CHF - cirrhosis - nephrotic syndrome - pulm edema) - HTN - hypercalcemia

16. What is the clincial use for Misoprostol?
Prevention of NSAID- induced peptic ulcers - maintains a PDA.
constipation - flushing - edema - CV effects (CHF - AV block - sinus node depression) - and torsade de pointes (Bepridil)
Staphlococcus aureus
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.

17. How can the t1/2 of INH be altered?
Rash - Pseudomembranous colitis
Fast vs. Slow Acetylators
Hydralazine and Minoxidil
- Ethanol - dialysis - & fomepizole

18. List the specific antidote for this toxin: Benzodiazepines
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.
- Flumazenil
Keratin containing tissues - e.g. - nails
very short acting

19. What type of neurological blockade would hexamethonium create?
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.
Used in combination therapy with SMZ to sequentially block folate synthesis
Hexamethonium is a nicotinic antagonist - and thus is a ganglionic blocker.
With supplemental Folic Acid

20. These drugs acts indirectly by releasing strored catecholamines in the presynaptic terminal
Amphetamine and Ephedrine
Ipratropium
1. Taken daily 2. No protection against STDs 3. Raises triglycerides 4. Depression - weight gain - nausea - HTN 5. Hypercoagulable state
Hydralazine and Minoxidil

21. What are major side effects of Methicillin - Nafcillin - and Dicloxacillin?
decrease AP duration - affects ischemic or depolarized Purkinje and ventricular system
Hypersensitivity reactions
Chronic anticoagulation.
GI disturbances.

22. Ca2+ channel blockers - site of action?
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.
- Methotrexate - 5 FU - 6 mercaptopurine
1. Hypoglycemia (more common with 2nd - generation drugs: glyburide - glipizide) 2. Disulfiram - like effects (not seen with 2nd - generation drugs).
Cell membrane Ca2+ channels of cardiac sarcomere

23. List the specific antidote for this toxin: Carbon monoxide
- ED 50 is less than the Km (less than 50% of receptors)
- Acetaldehyde - Nausea - vomiting - headache - & hypotension
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).
-100% oxygen - hyperbaric

24. How do Sulfonamides act on bacteria?
Erectile dysfunction.
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
Penicillin.
decrease conduction velocity - increase ERP - increase PR interval

25. Resistance mechanisms for Cephalosporins/Penicillins
Beta - lactamase cleavage of Beta - lactam ring
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.
decrease conduction velocity - increase ERP - increase PR interval
Clomiphene is a partial agonist at estrogen receptors in the pituitary gland. Prevents normal feedback inhibition and increses release of LH and FSHfrom the pituitary - Which stimulates ovulation.

26. What is the MOA of Griseofulvin?
- Ammonium Chloride
Anaerobic infections (e.g. - B. fragilis - C. perfringens)
Interferes with microtubule function - disrupts mitosis - inhibits growth
- Cloazapine - carbamazapine - colchicine - PTU

27. What is combination TMP- SMZ used to treat?
- Cimetidine - ketoconazole - grapefruit juice - erythromycin - INH - sulfonamides
Norepinephrine
DHPG (dihydroxy-2- propoxymethyl guanine)
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia

28. What is the category of drug names ending in - barbital (e.g. Phenobarbital)
Well tolerated in general but occasionally - Nephrotoxicity - Ototoxicity - Thrombophlebitis - diffuse flushing='Red Man Syndrome'
Babiturate.
Polymyxin B - Polymyxin E
Saquinavir - Ritonavir - Indinavir - Nelfinavir

29. What are Aminoglycosides synergistic with?
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome
Beta - lactam antibiotics
Oral treatment of superficial infections
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention

30. What is the clinical use for Sucralfate?
Lidocaine - Mexiletine - Tocainide
hypertrichosis - pericardial effusion - reflex tachycardia - angina - salt retention
Peptic ulcer disease.
- S- phase anti - metabolite Pyr analogue - Colon - solid tumors - & BCC/ - Irreversible myelosuppression

31. What additional side effects exist for Ampicillin?
Does not cross
Pseudomembranous colitis (C. difficile) - fever - diarrhea
Rash - Pseudomembranous colitis
Non - Nucleosides

32. What are are the Sulfonylureas (general description) and What is their use?
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
Inhibit viral DNA polymerase
very short acting
depresses ectopic pacemakers - especially in digoxin toxicity

33. What is the effect of epinephrine infusion on bp and pulse pressure?
Topical and Oral - for Oral Candidiasis (Thrush)
- Ammonium Chloride
Increased systolic and pulse pressure - decreased diastolic pressure - and little change in mean pressure.
fetal renal toxicity - hyperkalemia

34. What are the clinical uses for Aztreonam?
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.
depresses ectopic pacemakers - especially in digoxin toxicity
Gram - rods: Klebsiella species - Pseudomonas species - Serratia species
Methylzanthine; desired effect is bronchodilation - may cause bronchodilation by inhibiting phosphodiesterase - enzyme involved in degrading cAMP (controversial).

35. What is the MOA of Polymyxins?
For serious - Gram + multidrug - resistant organisms
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.
Cilastatin

36. What are common serious side effects of Aminoglycosides and What are these associated with?
Nephrotoxicity (esp. with Cephalosporins) - Ototoxicity (esp. with Loop Diuretics)
-100% oxygen - hyperbaric
Inhibits reabsorption of uric acid.
Local anesthetic.

37. What is a possible toxicity of Ticlopidine - Clopidogrel usage?
Neutropenia (ticlopidine); reserved for those who cannot tolerate aspirin.
Protease Inhibitors and Reverse Transcriptase Inhibitors
Tetracycline - Doxycycline - Demeclocycline - Minocycline
Acetylcholine esterase

38. What are two processes Corticosteroids inhibit leading to decreased inflammation?
The PT.
1. Phospholipase A2 is prevented from releasing arachidonic acid 2. Decreases protein synthesis thus lowering amount of Cyclooxygenase enzymes
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.
- DNA intercalator - Hodgkin's - myeloma - sarcoma - and solid tumors - Cardiotoxicity & alopecia

39. Antimicrobial prophylaxis for Gonorrhea
Botulinum
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.
hypertrichosis - pericardial effusion - reflex tachycardia - angina - salt retention
Ceftriaxone

40. Guanethidine enhances the release of Norepi?
- Protamine
Leukotrienes increasing bronchial tone.
No - it inhibits the release of Nor Epi
Rifampin

41. Adverse effects of Captopril?
decrease
fetal renal toxicity - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.
Beta Blockers

42. Which drug(s) cause this reaction: Adrenocortical Insufficiency
Norepinephrine
Binding to the presynaptic alpha 2 release modulating receptors
AZT
- Glucocorticoid withdrawal

43. Acetazolamide - site of action?
- Penicillin
Inhibit viral DNA polymerase
proximal convoluted tubule
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.

44. List the specific antidote for this toxin: Iron
- Deferoxamine
Inhibits reabsorption of uric acid.
Constant FRACTION eliminated per unit time.(exponential)
Aminoglycosides

45. For Heparin What is the Route of administration
sedation - positive Coombs' test
Paranteral (IV - SC)
cholestyramine - colestipol
vascular sm. Mus.: Nifedipine>Diltiazem>Verapamil

46. Which diuretics increase urine Ca2+?
Antileukotriene; blocks synthesis by lipoxygenase.
Initially vasoconstriction would increase bp - but then it acts on central alpha -2 receptors to decrease adrenergic outflow resulting in decreased bp.
loop diuretics - spironolactone
INH: Injures Neurons and Hepatocytes

47. What are the clinical indications for neostigmine?
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.
Topical and Oral - for Oral Candidiasis (Thrush)
No
Post - op and neurogenic ileus and urinary retention - myasthenia gravis - and reversal of neuromuscular junction blockade (post - op) through anticholinesterase activity.

48. MOA: Block protein synthesis at 50s subunit
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis
ACE inhibitor.
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
- Estrogen receptor antagonist - Breast CA - increased endometrial CA risk

49. How is Ribavirin used clinically?
Norepinephrine
TMP- SMZ
- Haloperidol - chlorpromazine - reserpine - MPTP
for RSV

50. Toxic effects of TMP include?
Hypersensitivity reactions
Megaloblastic anemia - Leukopenia - Granulocytopenia
Oral
atropine - homatropine - tropicamide