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Pharmacology > Hemostasis > Flashcards

Hemostasis Flashcards

1
Q

Hemostasis involves a complex, rapid, localized, integrated interaction between what four processes

A

blood vessels
platelets
coagualtion cascade
fibrinolysis

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2
Q

What are the four components of hemostasis activated by endothelial disruption

A

rapid vasoconstriciton
immediate platelet adherence to collagen
coagulation (intrinsic/extrinsic)
fibrnolysis via tPA

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3
Q

Platelets are formed by —–, where?

A

megakaryocytes in bone marrow

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4
Q

What is the normal platelet amount in plasma

A

150,000-300,000/uL

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5
Q

What is the platelet half-life

A

9-10 days

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6
Q

What three types of storage granules are released when platelet secretion occurs

A

alpha granules

dense granules

lysosomal vesicles

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7
Q

What are the four distinct functions of platelets in response to vascular damage

A

places seal over endothelium (maintains integrity)

stops initial bleeding via formation of platelet plugs

stabilizes platelet plug

promotes vascular healing

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8
Q

List the events of platelet adhesion

A

damaged endothelium with exposed collagen»factor VIII:vWF complex binds exposed collagen to platelet surface receptor (GP Ib)

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9
Q

List the three main events of platelet aggregation

A

damaged endothelim initiates coagulation

activation of platelets via dense granule release of ADP»>promotes platelet aggregation

platelet shape change, decreased cAMP activity»exposed GPIIb and GPIIIa receptors for fibrinogen binding sites (calcium dependent)

increased phosphoplipase activity»thromboxane A2 formation

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10
Q

What are the two pathways of the coagulation pathway that leads to fibrin formation

A

contact activation pathway (intrinsic)

tissue factor pathway (extrinsic)

*both pathways activate the COMMON FINAL pathway of FACTOR Xa

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11
Q

What are coagulation factors

A

serine proteases which act by cleaving downstream proteins

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12
Q

What are the four clotting factors with calcium-binding properties that are vitamin K dependent

A

II, VII, IX, X

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13
Q

What is factor IV

A

calcium ion

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14
Q

What test is used to measure the extrinsic pathway

A

PT

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15
Q

What test is used to measure the intrinsic pathway

A

PTT

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16
Q

What serine protease does factor Xa activate

A

Thrombin

*prothrombin»>thrombin

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17
Q

What serine protease does thrombin activate

A

Fibrin

*fibrinogen»>fibrin

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18
Q

What four biological mechanisms are in place to control excess coagulation

A

increased blood flow (washout excess factors)

antithrombin III via heparin induced activity

prostacyclin via inhibiting thromboxane A2

protein C activation»fibinolysis

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19
Q

What serine proteases does ATIII inhibit

A

IX, X, XI, XII

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20
Q

Plasminogen activation results in

A

formation of plasmin (serine protease) which lyse fibrin clots

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21
Q

How are the endogenous plasminogen activators classified

A

intrinsic and extrinsic

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22
Q

Name the three intrinsic plasminogen activators

A

factor XIIa

kallikrein

protein C

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23
Q

Name the two extrinsic plasminogen activators

A

tPa

urokinase

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24
Q

Name the two Exogenous plasminogen activators

A

streptokinase

rt-PA

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25
Q

How is thrombin involved in fibrinolysis

A

thrombin in the presence of thrombomodulin activates protein C

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26
Q

What is the main MOA of protein C

A

inactivates the inhibitor of plasminogen activator

*allows plasminogen»>plasmin conversion

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27
Q

Plasmin has what effect on clots and platelets

A

lysis of clots (fibrin)»fibrin split products

  • cleaves GP receptors
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28
Q

Heparin is classified as an

A

anticoagulant

29
Q

What is the MOA of heparin

A

binds to ATIII causing a conformational change»>1000X more potent

ATIII inhibits IX, X, XII, XII clotting proteases by forming stable complexes with them

30
Q

Heparin dosaging depends upon

A

the desired effect

31
Q

The desired effect of heparin can be classifed as

A

partial heparinziation

complete heparinization

32
Q

partial heparinization is used in what type of procedure

A

vascular (CEA, AAA resections)

dose generally 100 units/kg

33
Q

Complete heparinization is used in what type of procedure

A

CPB

dose generally 300-400 unis/kg

34
Q

1 unit of heparin is equal to ____mg

A

1

35
Q

Heparin follows zero order kinetics, what does this mean for how it is eliminated

A

a constant AMOUNT of drug is eliminated per unit of time»>linear rate of elimination and NON-linear decrease in plasma concentration

36
Q

What enzyme metabolizes heparin and where is it located

A

heparinase, located in the liver

37
Q

What tests determine the degree of heparinization

A

PTT»for low doses (1.5-2 times pre-heparin value)

ACT»for high doses (400-500 seconds)

38
Q

What are the three SE of heparin administration

A

Hemorrhage

Allergic rxn (beef/pork preparations)

Thrombocytopenia (encourages clot formation)

39
Q

Thrombocytopenia induced heparin administration is categorized as

A

mild thrombocytopenia

Heparin-induced Thrombocytopenia and Thrombosis (HITT) syndrome

40
Q

Mild thrombocytopenia caused by heparin results when

A

platelets drop below 100,000

*resolves on own

41
Q

HITT syndrome caused by heparin results when

A

platelets drop below 50,000

42
Q

HITT occurs do to the formation of

A

antibodies that attack platelets

*large doses of heparin causes upregulation of platelets»>antibodies attack platelets»>increased activation»>thrombosis and thrombocytopenia

43
Q

Are patient’s who receive heparin candidates for regional anesthesia

A

NOOO!!!!

44
Q

Fractionated (LMWH) heparins display what type of activity

A

Antifactor Xa/Antifactor IIa

  • more pronounced AF Xa activity
45
Q

What is a prototype of fractionated heparin

A

enoxaparin

“parins”

46
Q

Factor Xa inhibitors are classifed as

A

direct

indirect

47
Q

Name one direct factor Xa inhibitor

A

Rivaro-Xa-ban

*propphylactic prevention of VTE

48
Q

Name one indirect factor Xa inhibitor

A

Fondaparinu-X

*DVT prophylaxis

49
Q

Name one Vitamin K antagonist

A

Warfarin

50
Q

What is the MOA of Warfarin

A

nucleus of warfarin is similar to vitamin K so it binds to VK binding site preventing formation of calcium binding sites on clotting factors II, VII, IX, and X

51
Q

Warfarin is administered

A

Orally ONLY

52
Q

What is used to monitor effects of warfarin

A

PT

*effective anticoagulation when PT is twice precoumadin PT

53
Q

Name a class of drugs that are direct thrombin IIa inhibitors

A

“aTRoban”

Argatroban

54
Q

What are the three MOA of thrombin inhibitors (IIa)

A

direct thrombin inhibition

inhibition of protein C (fibrinolysis)

promotes NO release»vasodilation

55
Q

Name three common drugs used as procoagulants

A

protamine sulfate

vitamin K

conjugated estrogen

56
Q

Protamine is a specific antagonist to

A

heparin

57
Q

Protamine in the absence of heparin acts as a

A

anticoagulant

58
Q

Why must protamine be administered slowly

A

causes histamine release»>venodilation»>decreased SVR

59
Q

Protamine should not be given when

A

those taking protamine containing insulins

allergic to fish

males with vasectomy or infertility

60
Q

What are the four classification of AntiPlatelet drugs

A

Cox inhibitors
GP IIb/IIIa inhibitors
PDE inhibitors
ADP antagonists

*given to patient’s with too many platelets

61
Q

Name an antiplatelet COX inhibitor

A

Aspirin

*inhibits prostaglandin synthesis by irreversibly inhibiting COX I

62
Q

Name three anitplatelet GP IIb/IIIa inhibitor

A

Tirofiban

Eptifibatide

Abcixmab

63
Q

Name one antiplatelet PDE inhibitor

A

Dipyridamole

64
Q

Name three antiplatelet ADP antagonists

A

Ticlopidine

Clopidogrel

Prasugrel

65
Q

Name a drug that promotes platelet aggregation

A

Desmopression (DDAVP)

*increases the release of factor VIII:vWF from vascular endothelium

66
Q

Name three antifibrinolytics

A

E-Aminocaproic Acid (amicar)

Tranexamic Acid

Aprotinin

67
Q

Antifibrinolytics should not be given to patients with

A

DIC

68
Q

Name the classes of drugs classified as thrombolytics

A

“KINASE”

“TEPLASE”

Pharmacology (27 decks)

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