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pharmacology > Drugs for Coagulation Disorders > Flashcards

Drugs for Coagulation Disorders Flashcards

1
Q

what is hemostasis?

A
  • vessel spasms, constricting the vessel and limiting blood flow to the site of injury
  • platelets bind with high affinity to the damaged vessel; activated platelets release ADP and thromboxane A2 which stimulate the activation of new platelets, platelet aggregation and vasoconstriction
  • thrombin is produced, thrombin will convert fibrinogen into fibrin, fibrin provides the scaffolding that forms a clot
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2
Q

when is the extrinsic pathway activated?

A
  • triggered when tissue thromboplastin is released from damaged cells (outside the circulation)
  • catalyzes for formation of factor Xa
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3
Q

when is the intrinsic pathway activated?

A
  • triggered when collagen is exposed at the site of vascular injury to blood components (inside the circulation)
  • catalyzes formation of factor Xa
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4
Q

when is the common pathway activated?

A
  • synthesis of factor Xa
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5
Q

TPA

A
  • cells adjacent to the clot release tissue plasminogen activator
  • converts plasminogen into plasmin
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6
Q

what is the mechanism of action of plasmin?

A
  • plasmin digests fibrin and destroys the clot
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7
Q

when is fibrinolysis initiated?

A
  • 24 to 48 hours after clot formation
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8
Q

what is included with thromboembolic disorders?

A
  • formation of non-therapeutic clots
  • occlusion of arterial vessels lead to MI and stroke
  • embolus; piece of stable thrombi breaks off and lodges in smaller blood vessels
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9
Q

what is included in bleeding disorders?

A
  • thrombocytopenia (bone marrow suppression)
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10
Q

what are the most commonly prescribed coagulation modifiers?

A
  • anticoagulants
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11
Q

what drug class would be given to inhibit specific clotting factors?

A
  • anticoagulants
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12
Q

what drug class would be given to inhibit platelet actions?

A
  • anticoagulants

- antiplatelets

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13
Q

what drug class would be given to dissolve a clot?

A
  • thrombolytics
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14
Q

what drug class would be given to inhibit the destruction of fibrin?

A
  • antifibrinolytics
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15
Q

what is the mechanism of action of anticoagulant drugs?

A
  • modulate coagulation cascade and thrombin formation

- lengthen clotting times and prevent thrombi from forming in veins and arteries

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16
Q

in cases of MI or stroke, how would anticoagulants be administered? give an example

A
  • IV or SC for rapid onset of action (ex. heparin)
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17
Q

what are the 5 anticoagulant drugs?

A
  • heparin
  • warfarin
  • low molecular weight heparins
  • direct thrombin inhibitors
  • direct acting factor Xa inhibitors
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18
Q

how is heparin administered?

A
  • IV or SC
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19
Q

where is heparin made?

A

-found in liver and lining of blood vessels

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20
Q

what is heparin’s antidote?

A
  • protamine sulphate
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21
Q

how is warfarin administered?

A
  • PO
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22
Q

what is warfarin’s antidote?

A
  • vitamin K
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23
Q

what is a low molecular weight heparin antidote?

A
  • protamine sulphate
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24
Q

what is the mechanism of action of heparin?

A
  • catalyzes the inactivation of thrombin
  • enhances the ability of antithrombin III to inactivate thrombin and clotting factors
  • thrombin no longer available to convert fibrinogen into fibrin
  • inhibition of factor Xa, inhibits intrinsic and extrinsic pathways of the clotting cascade
25
Q

what is heparin prescribed for?

A
  • used for prevention of venous thrombosis, pulmonary embolism, disseminated intravascular coagulation, treatment in MI and stroke
26
Q

what is it important to monitor for with heparin?

A
  • bleeding
27
Q

what is the mechanism of action of low molecular weight heparins?

A
  • same mechanism of action as heparin, but more specific to factor Xa
  • produces a more stable response than unfractioned heparin since thrombin remains active
28
Q

what are some benefits of low molecular weight heparin?

A
  • reduced risk for thrombocytopenia
  • longer duration of action, reduced dosing frequency
  • drug class of choice for the prevention of DVT
29
Q

what is the mechanism of action of warfarin?

A
  • blocks synthesis of clotting factors thrombin, VIIa, IXa and Xa
  • precursors require carboxylation to become active
  • carboxylation linked to oxidation of vitamin K to vitamin K epoxide
  • inhibits vitamin K epoxide reductase
30
Q

what is vitamin K essential for?

A
  • clotting
31
Q

how is vitamin K epoxide recycled to its reduced form?

A
  • vitamin K epoxide is not used in the body

- vitamin k epoxide reductase recycles it back to vitamin K

32
Q

what do you closely monitor for when patient is on both heparin and warfarin?

A
  • spontaneous bleeding
33
Q

what should patients avoid when taking warfarin?

A
  • avoid vitamin-K rich foods because it reduces the effectiveness of the drug
  • strenuous activities that could result in an injury
34
Q

what is the mechanism of action for direct acting thrombin inhibitors?

A
  • prevents conversion of fibrinogen to fibrin, inhibiting clot formation
35
Q

direct acting thrombin inhibitors are used to reduce the risk of what?

A
  • stroke, systemic embolism in clients with A fib, DVT, pulmonary embolism
36
Q

what circumstance are direct acting thrombin inhibitors used as an alternative therapy?

A
  • heparin induced thrombocytopenia
37
Q

when would praxbind (direct acting thrombin inhibitor antagonist) be used?

A
  • life threatening bleeding or uncontrolled bleeding

- emergency surgeries

38
Q

what is the mechanism of action of the direct acting factor Xa inhibitors?

A
  • inhibits intrinsic and extrinsic pathways of the coagulation cascade
  • reduces thrombin formation and development of thrombi; no direct effects on thrombin or platelets
39
Q

direct acting factor Xa inhibitors are used to to prevent/ treat what?

A
  • deep vein thrombosis

- reduces the risk of pulmonary emboli in patients undergoing knee or hip replacements

40
Q

what caution precautions should be taken with anticoagulant drugs?

A

-patients with hemorrhagic disorders, recent trauma, spinal puncture, GI ulcers, recent surgery

41
Q

what is warfarin contraindicated with?

A
  • pregnancy and during lactation
42
Q

what are some common adverse effects with anticoagulant drugs?

A
  • bleeding
  • international normalized ratio (measures prothrombin levels)
  • prothrombin time (time required for clotting to occur)
43
Q

what are the three drug classes for anti platelet drugs?

A
  • irreversible cyclooxygenase inhibitors
  • adenosine diphosphate receptor antagonists
  • glycoprotein IIb and IIIa receptor antagonists
44
Q

what is the mechanism of action of irreversible cyclooxygenase inhibitors (ASPARIN)?

A
  • irreversibly blocks the activity of COX 1 and COX 2 enzymes
  • inhibits the synthesis of prostaglandins and thromboxane A2
45
Q

what are the benefits of irreversible cyclooxygenase inhibitors?

A
  • patients with established cardiovascular disease
46
Q

what is the mechanism of action for an ADP receptor antagonist?

A
  • irreversibly change the molecular conformation of ADP receptors present on platelets
  • platelets no longer receive chemical signal to aggregate, thereby inhibiting thrombus formation
47
Q
  • what is the mechanism of action of glycoprotein IIb and IIIa receptor antagonists?
A
  • glycoprotein IIb and IIIa enzymes are involved in platelet aggregation
  • antagonist activity at receptors prevents platelet aggregation and thrombus formation
48
Q

how are glycoproteins administered?

A
  • IV route
49
Q

what are caution precautions with antiplatelet drugs?

A
  • presence of any known bleeding disorders
  • recent surgery
  • closed head injuries
50
Q

what is the mechanism of action for thrombolytics drugs?

A
  • promote fibrinolysis by converting plasminogen to plasmin

- dissolve insoluble fibrin with intravascular emboli and thrombi

51
Q

when are thrombolytics drugs administered?

A
  • to dissolve pre-existing clots

- MI, pulmonary embolism, ischemic CVS, DVT

52
Q

what is the mechanism of action of streptokinase?

A
  • enzyme made by bacteria
  • can cause an immunological reaction
  • may result in systemic fibrinolysis
53
Q

what is the mechanism of action of the tissue plasminogen activators?

A
  • identical to human TPA
  • converts plasminogen to plasmin, which dissolves clots
  • specific to fibrin bound plasminogen
54
Q

what is contraindicated with thrombolytic drugs?

A
  • recent trauma or bleeding disorders
55
Q

what do you monitor for with thrombolytic drugs?

A
  • cerebral hemorrhage
56
Q

what is the antidote for thrombolytic drugs?

A
  • aminocaproic acid
57
Q

what is the mechanism of action for an antifibrinolytic drug and when is it used?

A
  • used to facilitate blood clotting and shorten bleeding time
  • post surgery to reduce bleeding at surgical sites
58
Q

what does aminocaproic acid do?

A
  • an enzyme inhibitor that inactivates plasmin

pharmacology (14 decks)

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