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Pharmacology Exam 3 > Agents that affect the clotting system > Flashcards

Agents that affect the clotting system Flashcards

1
Q

what clotting factors require vitamin k for synthesis?

A

IX, VII, X, Prothrombin (II)

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2
Q

what clotting factors require calcium to be activated?

A

XI, X, Prothrombin (II), Fibrinogen, XIII

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3
Q

how is clot formation reversed?

A

via plasminogen being activated into plasmin causing clot lysis

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4
Q

what does thrombin do?

A

activates platelets, factors VII, VIII, XIII

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5
Q

what does fibrinogen do?

A

cross link platelets

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6
Q

what does fibrin do?

A

forms clot

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7
Q

how is clot localized?

A

antithrombin III causes inactivation of thrombin, factors IX, X, XI, XII

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8
Q

what disorder is inadequate clotting?

A

hemophilia

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9
Q

what is thrombus?

A

clot that adheres to BV wall

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10
Q

what are white thrombi?

A

in arteries
associated with artherosclerotic plaques
platelet and fibrin strands
ischemic damage to tissues whose blood supply was compromised

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11
Q

what aure red thrombi?

A

in veins
associated with pooling of blood in extremities
RBC+fibrin
ischemic damage to tissues whose blood supply was compromised

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12
Q

what is thromboembolus?

A

piece of thrombus breaks off and travels through blood stream

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13
Q

what are the conditions for which anticoagulants are used?

A

thromboembolic diseases, after most kinds of surgery, during transfusions, in px with heart disease

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14
Q

tell me about calcium chelators

A

citric acid, EDTA, EGTA,
all chelate calcium
all work in vitro

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15
Q

tell me about the location and properties of heparin

A

located in mast cells
strong negative charge
prepared from cow lung and pig intestines
mixture of high and low molecular weight polymer
not synthetic- every batch must be individually tested for activity

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16
Q

what are the physiological effects of heparin

A

inhibits clotting in vivo and in vitro

activates enzymes lipoprotein lipases in blood

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17
Q

what is heparin’s mechanism of action

A

binds to antithrombin (a protease inhibitor) and increase its affinity for clotting factors by 1000x
heparin does not lyse existing clot

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18
Q

what does heparin help antithrombin inhibit at low doses

A

inhibit factor Xa- decreases formation of thrombin

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19
Q

what does heparin help antithrombin inhibit at high doses

A

inhibits thrombin and IXa, XIa, XIIa

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20
Q

how is heparin administered?

A

given by injection- TV or subq- too large to be absorbed by guts

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21
Q

can heparin pass the placenta?

A

no too large

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22
Q

how quick does heparin work?

A

immediate onset of action

t1/2=1hr

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23
Q

what is heparin degraded by?

A

heparinase in body

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24
Q

what kind of dose response does heparin have?

A

unpredictable dose response

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25
Q

toxicity of heparin? long term use?

A

major damage is bleeding

long term use- osteoporosis- due to osteoclast stimulation
thrombocytopenia- heparin induced thrombocytopenia
hypersensitivity

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26
Q

what is heparin overdosed treated with?

A

protanine sulfate

27
Q

what are the low molecular weight heparins?

A

enoxaparin

dalteparin

28
Q

tell me about enoxaparin and dalteparin

A

partially purified heparin
longer t1/2- 4hours
more effect on Xa than on thrombin
less osteoporosis and HIT
more predictable dose response
more expensive - not readily reversed by protamine
may cause spinal hematoma in pt who have had spinal tap/anesthesia

29
Q

tell me about fondaparinux

A 
heparin like drugs
purely synthetic 
t1/2=17 hours
acts only on factor Xa
can cross placenta
can't bind protamine
30
Q

what is derived from leeches and how does it function

A

hirudin- anticoagulant in leech saliva
directly inhibiting thrombin
enzyme inhibitor

31
Q

what drugs are related to hirudin? when are they used?

A

bivalirudin
desirudin
argatroban
used when pt has heparin induced thrombocytopenia

32
Q

what is the oral anticoagulant

A

warfarin

33
Q

warfarin mechanism

A

vitamin k analog
vitamin k is essential for synthesis of factors VII, IX, X, Prothrombin
works by inhibiting the enzymes that allow vitamin k to be recycled
recycling is inhibited and thus vitamin k deficiency

34
Q

what is warfarin’s initial onset?

A

24+ hours

35
Q

how is warfarin metabolized?

A

by metabolizing by p450- any drug that affect p450 can affect the concentration of warfarin

36
Q

what is the toxicity of warfarin?

A

hemorrhage

can pass placenta-> pregnancy category X

37
Q

what is the direct thrombin inhibitor?

A

dabigatran

38
Q

what is dabigatran?

A

prodrug- inhibits the enzyme thrombin

works within an hour

39
Q

what is the side effect of dabigatran?

A

se: hemorrhage

40
Q

what are the factor Xa inhibitors?

A

rivaroxaban
apixaban
rapid onset

41
Q

what are the side effects of rivaroxaban and apixaban?

A

bleeding after spinal tap or spinal surgery

42
Q

what are the platelet inhibitors?

A 
thrombin receptor blocker
adp inhibitors
fibrinogen inhibitors
COX inhibitors
phosphodiesterase inhibitors
platelet count reducer
43
Q

what is the thrombin receptor blocker?

A

vorapaxar

44
Q

how does vorapaxar work?

A

blocks the platelet thrombin receptor

45
Q

who should be cautious of vorapaxar

A

use carefully in px with history of intracranial bleeding

46
Q

what are the adp inhibitors?

A

ticlopidine
clopidogrel
prasugrel
ticagrelor

47
Q

how does ticlopidine, clopidogrel, prasugrel, ticagrelor work?

A

adp receptor blockers- inhibit adp binding to platelet inhibitors

48
Q

what is the side effect of ticlopidine

A

neutropenia, agranulocytosis

49
Q

how are clopidogrel, prasugrel, ticagrelor different?

A

difference is in pharmacokinetics

50
Q

what are the fibrinogen receptor inhibitors?

A

abciximab
tirofiban
eptifibatide

51
Q

how do abciximab, tirofiban, eptifibatide work?

A

all prevent platelet aggregation

all given iv

52
Q

what can abciximab, tirofiban, eptifibatide cause?

A

thrombocytopenia

53
Q

what kind of molecule is abciximab?

A

monoclonal antibody vs. receptors

54
Q

what is the COX inhibitor?

A

aspirin

55
Q

how does aspirin work?

A

inhibit TXA2 synthesis (cyclooxygenase inhibitor)- decreases platelet aggregation

56
Q

what are the phosphodiesterase inhibitors?

A

cilostazol, dipyridamole

57
Q

mechanism of cilostazol and dipyridamole

A

inhibits the enzyme that breaks down cAMP

58
Q

what is the plate count reducer?

A

anagrelide

59
Q

mechanism of anagrelide

A

decrease platelet formation, maturation and number

60
Q

what are the contraindications for all anticoagulants?

A

bleeding disorder- bleeding in GI tract
severe hypertension
after surgery in eye, brain, spinal cord

61
Q

what are the thrombolytic agents (agents that dissolve formed clots)?

A

streptokinase
urokinase
tissue plasminogen activator

62
Q

what are the mechanisms of streptokinase, urokinase, tissue plasminogen activator?

A 
all are enzymes
all given IV 
all convert plasminogen to plasmin 
plasmin hydrolyzes fibrin
plasmin degrades fibrinogen and factors V and VII
63
Q

what are the hemostatic agents? what do hemostatic agents do?

A

aminocaproic acid and tranexamic acid

enhance clotting

64
Q

how do aminocaproic acid and tranexamic acid work?

A

inhibits plasmnogen activation- enzyme inhibitor

Pharmacology Exam 3 (4 decks)

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