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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. How do Sulfonamides act on bacteria?
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
glaucoma - urinary alkalinization - metabolic alkalosis - altitude sickness
Blocks Influenza A and RubellA; causes problems with the cerebellA
Decreased uptake or Increased transport out of cell

2. List the mechanism - clinical use - & toxicity of Cyclophosphamide.
Premature infants - because they lack UDP- glucuronyl transferase
Pituitary hormone.
When pts have Low CD4+ (< 500 cells/cubic mm) or a High Viral Load
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.

3. What is the clinical use for Warfarin?
Chronic anticoagulation.
vasodilator - increases cGMP to induce smooth muscle relaxation (arterioles>veins; afterload reduction)
is resistant
Hemolytic anemia

4. What are three unwanted effects of Mifepristone?
Lipoxygenase
Hypersensitivity reactions
1. Reliable (<1% failure) 2. Lowers risk of endometrial and ovarian cancer 3. Decreased incidence of ectopic pregnancy 4. Lower risk of pelvic infections 5. Regulation of menses
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain

5. A 12yo patient was treated for a reaction to a bee sting - What drug provides the best coverage of sympathomimetic receptors?
Amphotericin B - Nystatin - Fluconazole/azoles
Epinephirine(Alpha1 -2 and Beta 1 -2)
- Oral Contraceptives
- Methylene blue

6. What is the clinical use for Nystatin?
Cilastatin
Topical and Oral - for Oral Candidiasis (Thrush)
1. Acarbose 2. Miglitol
Sildenafil fills the penis

7. Which drug(s) cause this reaction: Cough?
Wide spectrum of systemic mycoses: Cryptococcus - Blastomyces - Coccidioides - Aspergillus - Histoplasma - Candida - Mucor
Onchocerciasis ('river blindness'-- rIVER- mectin)
Binds 30S subunit and prevents attachment of aminoacyl - tRNA - Bacteriostatic
- ACE inhibitors (Losartan>no cough)

8. Name two bile acid resins.
Fast vs. Slow Acetylators
- Cloazapine - carbamazapine - colchicine - PTU
Resistant Gram - infections
cholestyramine - colestipol

9. List the mechanism - clinical use - & toxicity of 6 MP.
- inhibits HGPRT (pur. Syn.) - Luk - Lymph
- Alkalate DNA - Brain tumors - CNS toxicity
- Acetaldehyde - Nausea - vomiting - headache - & hypotension
constipation - flushing - edema - CV effects (CHF - AV block - sinus node depression) - and torsade de pointes (Bepridil)

10. Resistance mechanisms for Sulfonamides
first dose orthostatic hypotension - dizziness - headache
- Atropine & pralidoxime
Inhibits IMP Dehydrogenase (competitively) - and therefore blocks Guanine Nucleotide synthesis
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis

11. Ibutilide - toxicity?
- Daunorubicin & Doxorubicin
Acetaminophen has antipyretic and analgesic properties - but lacks anti - inflammatory properties.
torsade de pointes
1) Hypersensitivity reactions 2) Increased nephrotoxicity of Aminoglycosides 3) Disulfiram - like reaction with ethanol (those with a methylthiotetrazole group - e.g. - cefamandole)

12. How do you calculate maintenance dose?
Increased systolic and pulse pressure - decreased diastolic pressure - and little change in mean pressure.
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.
toxic
dizziness - flushing - constipation (verapamil) - nausea

13. Where does Griseofulvin deposit?
HTN - CHF - calcium stone formation - nephrogenic DI.
Keratin containing tissues - e.g. - nails
NE increases bp - Which stimulates baroreceptors in the carotid sinus and the aorta. The CNS signals through vagal stimulation to decrease heart rate.
Can affect absorption - bioavailability - or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying.

14. For Warfarin What is the Lab value to monitor
Flutamide is a nonsteroidal competitive inhibitor of androgens at the testosterone receptor - used in prostate carcinoma.
PT
Useful in muscle paralysis during surgery or mechanical ventilation.
vascular sm. Mus.: Nifedipine>Diltiazem>Verapamil

15. For Heparin What is the Treatment for overdose
Protamine sulfate
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide
Ld= (CpxVd)/F Cp=plasma conc. F= Bioaval.
No - warfarin - unlike heparin - can cross the placenta.

16. What is the formula for Clearance (CL)
AluMINIMUM amount of feces.
CL= (rate of elimination of drug/ Plasma drug conc.)
Antifungal.
1. Bleeding 2. Teratogenicity 3. Drug - drug interactions

17. Ethacrynic Acid - toxicity?
Suramin
- A57Blue lines in gingiva & long bones - Encephalopathy & Foot drop - Abdominal colic / - Sideroblastic anemia
- Chloramphenicol - benzene - NSAIDS - PTU - phenytoin
NO HYPERURICEMIA - NO SULFA AllERGY; same as furosemide otherwise

18. A fellow passenger on a Carnival cruise ship looks pale and diaphoretic - What antimuscarinic agent would you give them?
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome
Slow - limited by half lives of clotting factors
Blastomyces - Coccidioides - Histoplasma - C. albicans; Hypercortisolism
scopolamine

19. List the specific antidote for this toxin: Copper
- Penicillamine
Leukotrienes increasing bronchial tone.
- polymyxins
No. Atropine is used to reduce urgency in mild cystitis. So it would aggravate the urinary retention.

20. Adverse effects of Losartan?
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
- Formaldehyde & formic acid - severe acidosis & retinal damage
fetal renal toxicity - hyperkalemia
- Alkalating agents+cisplatin - Doxorubicin+Dactinomycin - Bleomycin - Etoposide

21. Resistance mechanisms for Macrolides

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22. How is Trimethoprim used clinically?
sedation - sleep alterations
Used in combination therapy with SMZ to sequentially block folate synthesis
Pretreat with antihistamines and a slow infusion rate
Md= (CpxCL)/F Cp= plas. Conc. CL=clear. F=bioaval.

23. What is the category of drug names ending in - azepam (e.g. Diazepam)
Tetracycline - Doxycycline - Demeclocycline - Minocycline
Benzodiazepine.
It acts presynaptically to increase NE release.
- Steroids - Tamoxifen

24. Acetazolamide - mechanism?
Inhibits cell wall mucopeptide formation - Bactericidal
alpha -1 > alpha -2; used as a pupil dilator - vasoconstrictor - and for nasal decongestion
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.

25. What is the mecanism of action - effective period - and ineffective period of use for Cromolyn in treating Asthma?
- Chloramphenicol - benzene - NSAIDS - PTU - phenytoin
Prevents release of mediators from mast cells. Effective only for the prophylaxis of asthma. Not effective during an acute attack.
Bethanechol - Neostigmine - physostigmine
cardiac muscle: Verapamil>Diltiazem>Nifedipine

26. What physiological effects was the Anes using Atropine to tx
SLUD (salivation - Lacrimation - urination - Defecation)as well as airway secretion - GI motility - acid secretions
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome
- Formaldehyde & formic acid - severe acidosis & retinal damage

27. What is the enzyme inhibited - the effect of this inhibition - and the clinical use of the antiandrogren Finasteride?
Buy AT 30 - CELL at 50'
Useful in muscle paralysis during surgery or mechanical ventilation.
Polymyxin B - Polymyxin E
Finasteride inhibits 5 Alpha - reductase - this decreases the conversion of testosterone to dihydrotestosterone - useful in BPH

28. What is a possible toxicity of Alpha - glucosidase inhibitors used in type -2 diabetes?
Long.
proximal convoluted tubule - thin descending limb - and collecting duct
Spironolactone - Triamterene - Amiloride (the K+ STAys)
GI disturbances.

29. What is the category of drug names ending in - operidol (e.g. Haloperidol)
Methylation of rRNA near Erythromycin's ribosome binding site
Onchocerciasis ('river blindness'-- rIVER- mectin)
Butyrophenone (neuroleptic).
Penicillin - G

30. IV Penicillin
Sucralfate cannot work in the presence of antacids or H2 blockers because it requires an acidic environment to polymerize.
Penicillin - G
block Na+ channels in the cortical collecting tubule
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity

31. Dobutamine used for the tx of shock acts on Which receptors
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.
Systemic mycoses
Beta1 more than B2
Same as penicillin. Act as narrow spectrum antibiotics

32. Why is carbachol and pilocarpine useful in treatment of glaucoma?
first dose orthostatic hypotension - dizziness - headache
YES
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).
Imipenem

33. What is the category of drug names ending in - zosin (e.g. Prazosin)
Keratin containing tissues - e.g. - nails
Aminoglycosides - Tetracyclines
Alpha -1 antagonist
all except the K+ sparing diuretics Spironolactone - Triamterene - Amiloride

34. What are Amantadine - associated side effects?
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia
Polymyxins
- Disulfram & also sulfonylureas - metronidazole
Ataxia - Dizziness - Slurred speech

35. List the mechanism - clinical use - & toxicity of Vincristine.

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36. Which of the following would atropine administration cause? Hypothermia - bradycardia - excess salivation - dry flushed skin - or diarrhea
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow
hypertension - angina - arrhythmias
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.
Dry flushed skin - due to inhibition of sympathetic post - ganglionic blockade on muscarinic receptors of sweat glands. All others are opposite of What would be expected.

37. What is the category of drug names ending in - navir (e.g. Saquinavir)
Protease inhibitor.
Nitrates
The PTT.
NO AP duration effect. useful in V- tach that progresses to V- fib and in intractable SVT Last RESORT

38. Which individuals are predisposed to Sulfonamide - induced hemolysis?
Anaerobes
G6PD deficient individuals
decrease AP duration - affects ischemic or depolarized Purkinje and ventricular system
Oral treatment of superficial infections

39. Resistance mechanisms for Chloramphenicol
propanolol - esmolol - metoprolol - atenolol - timolol
Modification via Acetylation
Acetaminophen has antipyretic and analgesic properties - but lacks anti - inflammatory properties.
Inhibits xanthine oxidase - decresing conversion of xanthine to uric acid.

40. How does angiotensin II affect NE release?
Parkinson patients benefit from antimuscarinic agents through its inhibitory action within the indirect pathway.
1. Antipyretic 2. Analgesic 3. Anti - inflammatory 4. Antiplatelet drug.
carbonic anhydrase inhibitors - K+ sparing diuretics
It acts presynaptically to increase NE release.

41. Ethacrynic Acid - clinical use?
1. Pioglitazone 2. Rosiglitazone.
Binds to the Pyrophosphate Binding Site of the enzyme
Diuresis in pateints with sulfa allergy
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.

42. List the specific antidote for this toxin: Anticholinesterases (organophosphate.)
Atropine would also block the receptors in the ciliary muscle - causing an impairment in accommodation (cycloplegia).
- Atropine & pralidoxime
Pentamidine
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome

43. In What population does Gray Baby Syndrome occur? Why?
Hypersensitivity reactions
Premature infants - because they lack UDP- glucuronyl transferase
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.
Inhibit steroid synthesis - used in the treatment of polycystic ovarian syndrome to prevent hirsutism.

44. For Warfarin What is the Mechanism of action
Bismuth and Amoxicillin or Tetracycline; against Helobacter pylori
Impairs the synthesis of vitamin K- dependent clotting factors
- A57Blue lines in gingiva & long bones - Encephalopathy & Foot drop - Abdominal colic / - Sideroblastic anemia
Gram + and Anerobes

45. Hydrochlorothiazide - mechanism?
Penicillin.
As an anticholinesterase it increases endogenous ACh and thus increases strength.
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.
decrease conduction velocity - increase ERP - increase PR interval

46. What are three types of antacids and the problems that can result from their overuse?
aPTT (intrinsic pathway)
Flutamide is a nonsteroidal competitive inhibitor of androgens at the testosterone receptor - used in prostate carcinoma.
Lipoxygenase
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia

47. What are common toxicities associated with Tetracyclines?

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48. Mannitol - toxicity?
Amphetamine and Ephedrine
Dopamine; causes its release from intact nerve terminals
Chronic gout.
pulmonary edema - dehydration

49. What is the major toxic side effect of Penicillin?
Hypersensitivity reactions
decrease myocardial O2 consumption by: 1- decreasing end diastolic volume 2- decreasing BP 3- decreasing HR 4- decreasing contractility 5- decreasing ejection time
Dry flushed skin - due to inhibition of sympathetic post - ganglionic blockade on muscarinic receptors of sweat glands. All others are opposite of What would be expected.
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine

50. Name three ACE inhibitors?
Captopril - Enalapril - Lisinopril
Well tolerated in general but occasionally - Nephrotoxicity - Ototoxicity - Thrombophlebitis - diffuse flushing='Red Man Syndrome'
- aminoglycosides - loop diuretics - cisplatin
TMP- SMZ