Hemostasis Modifier Drugs - Ch. 55 Flashcards

1
Q

What is hemostasis?

A

Process that halts bleeding after injury to a blood vessel
1. Forms a platelet plug
2. Fibrin produced (clotting cascade, plasma proteins)

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1
Q

What are hemostasis modifier agents?

A

Anticoagulants
Antiplatelet drugs
Thrombolytic drugs
Hemostatic agents

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2
Q

What do anticoagulants do?

A

Inhibit the action or formation of clotting factors
Prevent clot formation

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3
Q

What do anti platelet drugs do?

A

Inhibit platelet aggregation
Prevent platelet plugs

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4
Q

What do thrombolytic drugs do?

A

Lyse existing clots

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5
Q

What do hemostatic agents do?

A

Promote blood coagulation

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6
Q

What is the final product of the clotting cascade?

A

Fibrin

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7
Q

What is the clotting/coagulation cascade divided into?

A

Intrinsic pathway
Extrinsic pathway

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8
Q

What is the other name for anticoagulants?

A

Blood thinners

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9
Q

How are anticoagulants used?

A

Prophylactically

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10
Q

What are anticoagulants used to prevent?

A

Clot formation (thrombus)
Emboli (dislodged clots)

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11
Q

What are anticoagulants not used for?

A

Do not use to lyse/break down existing clots

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12
Q

In what settings are anticoagulants used to prevent clot formation?

A

MI
Unstable angina
Atrial fibrillation
DVT e.g, major orthopaedic surgery
Indwelling devices (e.g, mechanical heart valves)
Pulmonary embolism

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13
Q

Examples of anticoagulants that all prevent clot formation?

A

Heparin and low molecular weight heparins (LMWH)
Warfarin -oral
Direct-Acting Oral Anticoagulants (DOACs)
-Direct factor X & Thrombin inhibitors

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14
Q

When is anticoagulant use contraindicated?

A

Known drug allergy
Acute bleeding process
Thrombocytopenia

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15
Q

What adverse effects are associated with anticoagulants?

A

Bleeding risk
-gums bleed
-nosebleeds
-unusual bruising
-anemia/low Hct
-tarry stools

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16
Q

What is the mechanism of action of Heparin?

A

Indirectly inhibits activity of multiple proteins on cascade

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17
Q

What proteins are inhibited by heparin?

A

-Thrombin (II)
-Factor Xa
-Intrinsic pathway factors

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18
Q

What is natural heparin?

A

Obtained from animal sources

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19
Q

how is heparin monitored because of its unpredictable dosage?

A

Activated partial thromboplastin times (aPTT)

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20
Q

What pathway does aPTT measure?

A

Intrinsic pathway

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21
Q

What do aPTTs need to be?

A

1.5 - 2.5 x greater than 40 sec (control)

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22
Q

How is Heparin administered?

A

Parenteral (IV or SC)

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23
Q

How long does it take for Heparin to be effective?

A

Seconds

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24
Q

What is the half life of Heparin?

A

Short half life
1-2 hours

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25
Q

What adverse effects are associated with Heparin?

A

Heparin-induced thrombocytopenia (HIT)
Hypersensitivity reactions

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26
Q

What is Heparin-induced thrombocytopenia (HIT)?

A

The body reacts to heparin in a way that causes platelets to clot instead of preventing them
-Increases blood clots
-1-5% population (>4 days of administration)
-stop heparin administration and use an alternative

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27
Q

What hypersensitive reactions does Heparin cause?

A

Urticaria
Fever
Chills

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28
Q

What is the antidote for heparin?

A

protamine sulfate

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29
Q

What does protamine sulphate do?

A

Reverses anticoagulant effects

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30
Q

Examples of low-molecular-weight heparins (LMWHs)?

A

Enoxaparin
Tinzaparin
Dalteparin

31
Q

What do Low-molecular-weight heparins (LMWHs) have that heparins don’t?

A

More predictable anticoagulant response

32
Q

low-molecular-weight heparins (LMWHs) do not require what?

A

Frequent lab monitoring
-Often given at home

33
Q

How are low-molecular-weight heparins (LMWHs) administered?

A

SC q12h

34
Q

What is the mechanism of action of low-molecular-weight heparins (LMWHs)?

A

Indirectly inhibits Factor X only

35
Q

What antidote is used for low-molecular-weight heparins (LMWHs)?

A

Protamine sulfate
(same as heparin)

36
Q

What are some other anticoagulant drugs?

A

Danaparoid
Fondaparinux

37
Q

What is Danaparoid?

A

anticoagulant that is structurally distinct from heparin
Alternative to heparin

38
Q

How is Danaparoid administered?

A

SC or IV

39
Q

What is Fondaparinux?

A

Synthetic anticoagulant

40
Q

How is Fondaparinux administered?

A

SC or IV

41
Q

Subcutaneous LMWH doses should be injected only in what area?

A

Abdomen only
-Rotate sites around abdomen

42
Q

What is an oral anticoagulant?

A

Warfarin (Coumadin)

43
Q

What is warfarin?

A

Modified coumarin

44
Q

What is the mechanism of action of Warfarin?

A

Vitamin K β€œantagonist”
-Reduces β€˜ready for action” clotting factors in plasma so clotting time is extended

45
Q

What is Vitamin K used for?

A

Production of several clotting factors (VII, IX, X, prothrombin) in liver cells

46
Q

What do Warfarin effects depend on?

A

Clotting factors turnover (proteins degradation)

47
Q

How long may Warfarin’s max effect take?

A

3-5 days
-effects start within 24 hours

48
Q

Patients may be started on 5 days on a combination of what anticoagulants?

A

LMWHs + warfarin
-then LMWH is withdrawn

49
Q

How is warfarin monitored?

A

Clotting lab test
-Prothrombin time (PT)
INR (international normalization reference ratio)

50
Q

What pathway does PT/INR measure?

A

Extrinsic

51
Q

For the drug to be therapeutic, PT needs to be within what range?

A

1.3-1.5 times the normal (control) level

52
Q

What is the normal target INR range?

A

2 to 3 x control
Some need to be 2.5 to 3.5 (normal is 0.8 to 1.2) eg mechanical heart valves

53
Q

If excessive PT/INR during Warfarin use what can begun?

A

Vit K

54
Q

How can Vitamin K be administered if excessive PT?INR?

A

IV (slow infusion) 4-8h effect
PO effect within 24 hours

55
Q

When is Warfarin use contraindicated?

A

Pregnancy
-Risk for fatal bleeding, teratogenicity and spontaneous abortion

-Use LMWH instead

56
Q

What should someone do is they are taking Warfarin?

A

Maintain intake of vitamin K
-Tomatoes, dark leafy green veggies)

Wear medical alert bracelet

Consult physician before taking other drugs because warfarin has many drug-drug interactions

57
Q

Warfarin administration may be started while the client is still on what drug?

A

Heparins
-until prothrombin times/INR indicate adequate anticoagulation

58
Q

How long does it take for the full therapeutic effect of warfarin ?

A

several days

59
Q

What are the advantages of Direct-Acting Oral Anticoagulants (DOACs) over Warfarin?

A

Rapid onset and offset
Fixed doses
No blood test
Few drug-drug interactions
no dietary concerns
Lower risk of bleeds

60
Q

Example of Direct-Acting Oral Anticoagulants (DOACs)??

A

dabigatran
rivaroxaban
apixaban
betrixaban
edoxaban

61
Q

What is the mechanism of action of Dabigatran?

A

Directly inhibits thrombin

62
Q

How is dabigatran administered?

A

PO

63
Q

Adverse effects associated with dabigatran?

A

GI disturbances
-Nausea, vomiting, abdominal pain, bloating

64
Q

What is the mechanism of action of rivaroxaban
apixaban, betrixaban and edoxaban?

A

Directly inhibit Factor Xa

65
Q

How is rivaroxaban, apixaban, betrixaban and edoxaban adminsitered (Factor X inhibitor DOACs)?

A

PO

66
Q

What is the antidote for dabigatran?

A

Idarucizumab (antibody)

67
Q

What is the antidote for Factor X inhibitor DOACs?

A

andexanet alfa (modified factor X)

68
Q

All DOACs use required what?

A

Annual renal function test
- if below min function, changed to Vit K antagonist

69
Q

All anticoagulants increase the risk for what?

A

Bleeding
-Mild to life-threatening

70
Q

What are signs of abnormal bleeding?

A

bleeding of gums while brushing teeth
unexplained nosebleeds
bruising
heavier menstrual bleeding
bloody or tarry stools, vomiting blood
bloody urine or sputum
abdominal pain

71
Q

What re some anti platelet agents?

A

Acetylsalicyclic acid (Aspirin) - 81 mg EC
Pentoxifylline
Clopdiprogel (plavix), prasurgel, ticlopidine
ticargrelor

72
Q

What is the mechanism of action of Aspirin?

A

Inhibits COX enzyme pathway in platelets (irreversible)

73
Q

What is the mechanism of action of clopidogrel?

A

Irreversible ADP receptor blocker
-effects last the entire life-time of the platelet

74
Q

What is the mechanism of action of ticargrelor?

A

Reversible ADP receptor blocker

75
Q

What are anti platelet drugs used for?

A

Antithrombotic effects
-Reduce risk of MI
-Reduce risk of stroke

76
Q
A