coagulation1-VI-qnz

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1-3. A 58-year-old business executive is brought to the

emergency department 2 h after the onset of severe

chest pain during a vigorous tennis game. She has a

history of poorly controlled mild hypertension and

elevated blood cholesterol but does not smoke. ECG

changes confirm the diagnosis of myocardial infarction.

The decision is made to attempt to open her occluded

artery.

1. Conversion of plasminogen to plasmin is acceleratedby

(A) Aminocaproic acid

(B) Heparin

(C) Lepirudin

(0) Reteplase

(E) Warfarin

Al

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d



2. If a fibrinolytic drug is used for treatment of

this woman's acute myocardial infarction, the

adverse drug effect that is most likely to occur is

(A) Acute renal failure

(B) Development of antiplatelet antibodies

(C) Encephalitis secondary to liver dysfunction

(0) Hemorrhagic stroke

(E) Neutropenia

3. If this patient undergoes a percutaneous coronary

angiography procedure and placement of a stent in

a coronary blood vessel, she may be given eptifi-

batide. The mechanism of eptifibatide anticlotting

action is

(A) Activation of antithrombin III

(B) Blockade of posttranslational modification of

clotting factors

(C) Inhibition of thromboxane production

(0) Irreversible inhibition of platelet ADP receptors

(E) Reversible inhibition of glycoprotein lIb/IlIa

receptors


d

e



4. The following graph shows the plasma

concentration of free warfarin as a function of time

in weeks for a patient who was treated with 2 other

agents, drugs B and C, on a daily basis at constant

dosage starting at the times shown. The most

accurate explanation for the observed changes in

warfarin concentration is that

(A) Drug B displaces warfarin from plasma proteins;

drug C displaces warfarin from tissue binding sites

(B) Drug B inhibits hepatic metabolism of warfarin;

drug C displaces drug B from tissue binding sites

(C) Drug B stimulates hepatic metabolism of warfarin;

drug C displaces warfarin from plasma protein

(D) Drug B increases renal clearance of warfarin;

drug C inhibits hepatic metabolism of drug B


c



5-7. A 65-year-old man is brought to the

emergency department 30 min after the onset of

right-sided weak ness and aphasia (difficulty

speaking). Imaging studies ruled out cerebral

hemorrhage as the cause of his acute symptoms of

stroke.

5. Prompt administration of which of the following

drugs is most likely to improve this patient's clinical

outcome?

(A) Abciximab

(B) Alteplase

(C) Factor VIII

(D) Streptokinase

(E) Vitamin K


b



6. Over the next 2 days, the patient's symptoms

resolved completely.To prevent a recurrence of this

disease, the patient is most likely to be treated

indefinitely with

(A) Aminocaproic acid

(B) Aspirin

(C) Enoxaparin

(D) Lepirudin

(E) Warfarin

7. If the patient is unable to tolerate the drug

identified in Question 6, he may be treated with

clopidogrel. Relative to ticlopidine, clopidogrel

(A) Has a shorter duration of action

(B) Is less likely to cause neutropenia

(C) Is more likely to induce antiplatelet antibodies

(D) Is more likely to precipitate serious bleeding

(E) Will have a greater antiplatelet effect


or heparin b

b



8-9. A 67-year-old woman presents with pain in her

left thigh muscle. Duplex ultrasonography indicates

the presence of deep vein thrombosis (DVT) in the

affected limb.

8. The decision was made to treat this woman with

enoxaparin. Relative to unfractionated heparin,

enoxaparin

(A) Can be used without monitoring the patient's

aPTT

(B) Has a shorter duration of action

(C) Is less likely to have a teratogenic effect

(D) Is more likely to be given intravenously

(E) Is more likely to cause thrombosis and throm-

bocytopenia


active parrial thromboblasm time !!

a



9. During the next week, the patient was started on

warfarin and her heparin was discontinued. Two

months later, she returned after a severe

nosebleed.Laboratory analysis revealed an INR

(international normalized ratio) of7.0 (INRvalue in

such awarfarin treated patient should be 2.5-3.5).

To prevent severe hemorrhage, the warfarin should

be discontinued and this patient should be treated

immediately with(A) Aminocaproic acid

(B) Desmopressin

(C) Factor VIII

(D) Protamine

(E) Vitamin x,K


e



10. A patient develops severe thrombocytopenia in

response to treatment with unfractionated heparin

and still requires parenteral anticoagulation. The

patient is most likely to be treated with

(A) Abciximab

(B) Aprotinin

(C) Lepirudin

(D) Plasminogen

(E) Vitamin K2

ANSWERS


c



1. Reteplase is the only thrombolytic drug listed.

Heparin and warfarin are anticoagulants that affect

activation or formation of clotting factors. Lepirudin

is a direct inhibitor of thrombin, and aminocaproic

acid is an inhibitor, not an activator, of the conver-

sion of plasminogen to plasmin. Th e answer is D.

2. The most common serious adverse effect of the

fibrolytics is bleeding, especially in the cerebral

circulation. The fibrinolytics do not usually have

serious effects on the renal, hepat ic, or

hematologic

SKILL KEEPER ANSWERS:

TREATMENT OF ATRIAL

FIBRILLATION (SEE

CHAPTERS 13 AND 14)

t , The padrenoceptor-blocking drugs(class lI ;eg,

propranolol,acebutolol)and calciumchannel -



blockingdrugs(class IV; eq , verapamil, diltiazem)

areusefulfor treating atrial fibrillation because

theyslowatrioventricular (AV) nodal conduction

and therebyhelpcontrol ventricularrate.Digoxin

isalsosometimes usedbecause it increases the

effective refractoryperiodin AVnodal tissue and

decreases AVnodal conductionvelocity.

2. With warfarin, one isalwaysconcernedabout

pharmacodynamic and pharmacokinetic drug

interactions.Noneof these antiarrhythmic

drugsare likely to cause a pharmacodynamic

interaction with warfarin. However, many other

drugs inhibit cytochromeP450 enzymes and

increasewarfarin'santithrombotic effect.

Patientstaking suchdrugsusuallyneed to

decrease their doseofwarfarin.

systems. Unlike heparin, they do not induce

anti platelet antib odies. The answer is D.



3. Eprifibatide is a reversible inhibitor of

glycoprotein

lIb/lIla, a protein on the surface of platelets that

serves as a key regulator of platelet aggregation.

Glycoprotein IIb/lIla receptor antagonists help pre-vent platelet-induced occlusion of coronar y stents.

The answer is E.

4. A drug that increases metabolism (clearance) of

the

anticoagulant will lower the steady-state plasma

concentration (both free and bound forms ),

whereas one that displaces the anticoagulant will

increase the plasma level of the free form only until

elimination of the drug has again lowered it to the

steady-state level.The answer is C.




5. Alteplase improves the clinical outcome in

patients

with ischemic stroke if given within 3 h after the

onset of symptoms, after ruling out hemorrhagic

stroke. Use of streptokinase results in unacceptably

high rates of bleeding. Glycoprotein IIb/lIla recep-

tor inhibi tors like abciximab have not been testedin

ischemic stroke. The answer is B.

6. Aspirin, an irreversible inhibitor of platelet

cyclooxygenase, prevents recurrence of TlAs and

ischemic stroke. The answer is B.

7. Ticlop idine and clopidogrel have similar mecha-

nisms of action and therapeutic efficacy. The key

difference between these 2 drugs is that clopidogrel

is less likely to cause hematologic adverse effects




(neutropenia, TTP) and, therefore, does not require

rout ine monitoring of blood cell counts during

therapy. The answer is B.

8. Enoxapar in is an LMW heparin. LMW heparins

have a longer half-life than standard hepar in and a

more consistent relationship between dose and

therapeutic effect. Enoxaparin is given subcuta-

neously, not intravenously. It is less, not more,

likely to cause thrombosis and thrombocytopenia.

Neither LMW heparins nor stand ard heparin are

teratogenic . The aPTT is not useful for monitoring

the effects of LMW heparins. The answer is A.

9. The elevated INR indicates excessive ant

icoagula-

tion with a high risk of hemorrhage. Warfarin

should be discontinued and vitamin K1 administered

to accelerate formation of vitamin K-dependent



factors. The answer is E.

10. Direct thrombin inhibitors such as lepirudin and

argatroban provide parenteral anticoagulation simi-

lar to that achieved with heparin , but the direct

thrombin inhibitors do not induce formation of

antiplatelet antibodies. The answer is C.

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