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Pulmonary Block > Week 5 Pharmacology > Flashcards

Week 5 Pharmacology Flashcards

1
Q

How does Heparin work?

A

Induces antithrombin
–> accelerates inhibition of thrombin and Factor Xa

Heparin has binding sites for both antithrombin and thrombin.
Thrombin cleaves part of antithrombin which causes antithrombin to wrap around and inhibit thrombin.

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2
Q

How do coumarol drugs work?

A

Inhibit reduction of Vit K in liver.

Vit K

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3
Q

What cleaves fibrin?

A

Plasmin

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4
Q

What holds fibrin together?

A

Covalent and non-covalent bonds.

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5
Q

Fibrin is crosslinked by what?

A

Factor XIIIa

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6
Q

What are fibrinopeptides?

A

Peptides released from the alpha and beta chains of fibrinogen. This allows for the terminal ends to now bind to other fibrin monomers.

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7
Q

What are D2E fragments?

A

Products resulting from plasmin breaking down of fibrin.

Elevated with liver disease.

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8
Q

How does the body respond to blood vessel injury?

A

Platelets aggregate at injury site

  • -> platelets are activated
  • -> platelets release granules
  • -> extrinsic clotting cascade begins
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9
Q

What is Protein C?

A

Vitamin K-dependent plasma protein anticoagulant

  • aka. Clotting Factor XIV (xymogen)
  • plays a role in preventing clotting, inflammation, cell death, and permeability of capillary membrane
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10
Q

What happens in Protein C deficiency?

A

Blood tends to clot more
ex. DVT
Risk of recurrent thrombotic diseases

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11
Q

How does warfarin effect Protein C?

A

Warfarin decreases the anticoagulant activity of Protein C.

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12
Q

What activates Protein C?

A

Thrombin

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13
Q

What is serum?

A

The liquid portion of blood that is leftover after the blood has been allowed to clot.
Therefore does not contain clotting factors.

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14
Q

Name some chelating agents.

A

Citrate

EDTA

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15
Q

What do chelating agents do?

A

Removes Calcium from Gla proteins in blood.

Prevents clotting!

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16
Q

What does thrombomodulin do?

A

Changes the substrate specificity of Thrombin
Thrombin-thrombomodulin complex activates Protein C.
–> Inactivates Factor Va, VIIIa
–> Fibrin production is inactivated
–> Anticoagulant activity

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17
Q

What is thrombin?

A

A pro-coagulant

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18
Q

What does thrombin do?

A

Converts fibrinogen to fibrin.
Activates platelets, Factor V, VIII, (XI), & XIII
Activates Protein C

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19
Q

What is standard treatment of DVT and PE?

A

Anticoagulant therapy.

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20
Q

What are some typical clinical features of PE?

A 
Dyspnea
Pleuritic pain
Hemoptysis
Loud P2 Heart sound
Rigors
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21
Q

What increases the likelihood of peripheral venous thrombosis?

A

Virchow’s Triad:

  • Stasis
  • Hypercoagulability
  • Endothelial damage

Polycythemia
Oral contraceptives
Dehydration

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22
Q

What is the most common heart rhythm in pts with PE?

A

Sinus tachycardia

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23
Q

Is hemoptysis associated with pneumonia?

A

No; very rarely.

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24
Q

Compare fibrinolytic therapy to heparin.

A

Fibrinolytic Therapay:

  • more expensive
  • more likely to bleed
  • more rapid decrease in pulm HTN for large PE
25
Q

After PE, what is the typical length of time that warfarin (coumadin) is given for?

A

3-6 months

26
Q

How long does it take for PE’s to dissolve?

A

Days to weeks after starting on anticoagulation Tx.

27
Q

What are some targets for anticoagulation?

A
  1. Anti-platelet
  2. Chelate Ca++
  3. Inhibit carbox’n of Gla proteins
  4. Anti-thrombin
  5. Directly inhibit thrombin
  6. Thrombolytic agent
28
Q

Name examples and describe anti-platelet agents.

A

ASA

  • inhibits COX
  • prevents synthesis of TXA2
  • prevents platelet activation and aggregation
29
Q

Coumarol drugs are also know as…

Name one.

A

blood thinners

ex. Warfarin

30
Q

What are couramol drugs used for?

How are they administered?

A

Long-term anti-coagulation in thrombosis-risk pts.

Can be taken orally (100% bioavailability)

31
Q

How can the action of coumarol be reversed?

A

Additional Vit K intake

Therefore must monitor INR continuously

32
Q

What is INR?

A

INR = [ Prothrombin(test) / Prothrombin(control) ] ^ ISI

33
Q

How does warfarin affect PT (prothrombin time)?

A

Warfarin prolongs prothrombin time.

34
Q

When is warfarin indicated?

A
  • prophylaxis and Tx of VTE
  • prophylaxis and Tx of atrial fib
  • valvular stenosis
  • heart valve replacement
  • MI
  • Antiphospholipid syndrome
35
Q

Name some Gla proteins.

Which has the longest half-life? shortest?

A

Prothrombin –> longest half-life
Factor VII –> shortest half-life
Factor IX
Factor X

36
Q

What initiates the extrinsic pathway?

A

External damage to blood vessel

  • -> releases Tissue Factor
  • -> binds to Factor VIIa
37
Q

What converts prothrombin to thrombin?

A

Factor Xa and Factor Va

38
Q

Why does warfarin need to be monitored so closely?

A

Narrow therapeutic index
Can increase risk of bleeding
Effectiveness altered by diet

39
Q

How is warfarin use monitored?

A

INR and PT

40
Q

What is the target INR for someone with previous VTE?

A

Target INR range: 2.0 - 3.0

41
Q

What does an INR < 2 suggest?

A

Increased risk of thromboembolism (& stroke & MI)

42
Q

What does an INR > 4.5 suggest?

A

Increased risk of bleeding

43
Q

What is a serpin?

A

SERPIN = SERine Protease INhibitor

ex. antithrombin

44
Q

What is PTT?

What does it measure?

A

PTT = Partial Prothromboplastin Time

Measures clotting factors in pt who is taking Heparin

45
Q

How does size of the Heparin chain affect fxn?

A

Factor Xa can be inhibited (via antithrombin) with any size Heparin chain.

Thrombin can be inhibited (via antithrombin) ONLY with Heparin chain > 18 sugars.

46
Q

What are some advantages of LMWH over UFH?

A
  • Decreased Heparin resistance
  • Don’t need lab monitoring
  • Higher bioavailability (90% vs 30%)
  • Longer plasma half-life (4-6 hrs vs 0.5-1 hr)
  • Less inhibition of platelet fxn
  • Lower incidence of thrombocytopenia and thrombosis
  • Less interaction with platelet factor 4
47
Q

How is Heparin administered?

A

IV

- Must be injected becuase it is highly charged.

48
Q

How can Heparin action be reversed?

A

Administration of protamine sulfate

protein that forms a complex with Heparin

49
Q

What is a serious risk of Heparin?

A

Fatal thrombocytopenia

50
Q

What is a type of synthetic Heparin?

A

Fondaparinux

51
Q

What agent directly inhibits Factor Xa?

A

Rivaroxaban

52
Q

What agent directly inhibits Thrombin?

A

Dabigatran

53
Q

How can the action of direct Thrombin/Factor Xa inhibition be reversed?

A

It can’t.

There’s no known antidote.

54
Q

What is an advantage of direct Thrombin/Factor Xa inhibitors?

A

Patient does not require close monitoring.

55
Q

How do Thrombolytic agents work?

A

Activate plasminogen to plasmin

56
Q

How are Thrombolytic agents administered?

A

IV

57
Q

What are some examples of thrombolytic agents?

A

Urokinase
Streptokinase (bacterial)
Tissue Plasminogen Activator “TPA” (recombinant)

58
Q

What are thrombolytic agents indicated for?

A

Ischaemic stroke caused by blood clot

Pulmonary Block (12 decks)

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