Pharma 8.1 Thrombolytic, Platelet, anticoagulant Drugs Flashcards Preview

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Flashcards in Pharma 8.1 Thrombolytic, Platelet, anticoagulant Drugs Deck (29):
1

Explain the physiological mechanism by which thrombi are cleared

Cleared via plasmin which cleaves fibrin to fibrin fragments.

Plasmin formed from circulating plasminogen which binds to fibrin strands. tPAs convert plasminogen to plasmin and are regulated by PAI-1. tPA released after endothelial damage.

2

What are the 2 methods by which fibrinolytic drugs can work? Give examples of the 2 types.

Generating plasmin themselves e.g. alteplase or by binding to and activating endogenous plasminogen e.g. strptokinase.

3

Explain why streptokinase can only be used once.

It is a bacterial product and therrefore produces an immune response. Body produces antibodies to it.

4

Why is a slow infusion of streptokinase recommended?

To prevent or counteract the transient hypotension that occurs upon infusion

5

Give 2 examples of recombinant tPA (r-tPA)

alteplase, reteplase

6

What situations would fibrinolytic drugs be indicated for?

acute MI, major PE, acute ischaemic stroke

7

What is the window of opportunity for fibrinolysis in an acute MI and an ischaemic stroke? Why is there a time frame?

MI - 12 hours

Stroke - 3 hours

Time frame because the thrombus becomes more resistant to lysis as it ages, where as the risks remain constant.

8

What are the ADRs of fibrinolytic agents?

increased risk of haemorrhage.

9

What are the major contra-indications for fibrinolytic therapy?

history of haemorhagic stroke, active peptic ulcer, recent surgery, uncontrolled hypertension, known coagulation defect

10

How would you diagnose a CVA after fibrinolytic therapy?

CT or MRI diagnosis

11

How would you treat serious bleeding post fibrinolytic therapy

transfusion of blood and inhibition of fibrinolytics and administration of tranexamic acid which competitively inhibits activation of plasmin.

12

What is the mechanism of action of vitamin K antagonists?

Vitamin K promotes synthesis of prothrombin and factors VII, IX, and X.

Antagonise these to prevent synthesis of prothrombin

13

Give an example vit K antagonist

warfarin

14

How is vit K antagonist administered?

Orally

15

How is vit K antagonist monitored? How long does it take to take effect?

monitored with INR

Gradual onset and persisting anticoagulant action on cessation of treatment

16

What ADRs are associated with vit K antagonists?

excessive bleeding or bruising. Teratogenic

17

How would you reverse vit K antagonists?

administration of IV vit K

18

How does heparin work?

heparin binds to antithrombin, increasing inhibition of thrombin and Xa

19

How is heparin administered? How long does it take to take effect? how is it monitored

Monitored with APTT (activated partial thrombin time)

Rapid onset and offset

IV or subcutaneous

20

What are the ADRs of heparin?

bleeding, thrombocytopenia, osteoporosis (long term)

21

How is heparin reversed?

Protamine sulphate causes dissociated of heparin/antithrombin complex and binds irreversibly to heparin

22

What are the 3 types of antiplatelet agents? Give examples of each

Thromboxane A2 inhibition - aspirin, dipyridamole

Platelet ADP receptor antagonist - ticlopidine, clopidogrel

GPIIb/IIa inhibitor 

23

What is the mechanism of action of thromboxane A2 inhibitors

Thromboxane A2 produced by activated platelets and causes platelet aggregation and vasoconstriction.

Aspirin inhibits COX and therefore platelet thromboxane A2 production

Dipyridamole inhibits platelet phosphodiesterase which inhibits thromoxane A2 production

24

How do platelet ADP receptor antagonists work?

ADP to ADP receptor interaction is one of the stimuli needed for platelet aggregation. Antagonising.

25

How do GpIIa/IIb inhibitors work?

inhibit the final common pathway of platelet aggregation

26

What is anticoagulation therapy?

Prevention of thromboembolism

27

What is fibrinolysis

Breakdown existing clot

28

What is antiplatelet therapy?

Preventing platelet aggregation

29

What is the difference between anticoagulants and antiplatelets?

Anticoagulants target clotting factors

Antiplatelets target platelets