Haemostasis, thrombosis and platelet function Flashcards Preview

Yr 2 - Pharmacology > Haemostasis, thrombosis and platelet function > Flashcards

Flashcards in Haemostasis, thrombosis and platelet function Deck (72)
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1

Which three drug groups decrease clotting?

  • Anticoagulants
  • Antiplatelet
  • Thrombolytics

2

What is thrombosis?

unwanted haemostatic plug in a blood vessel or the heart

3

What causes deep vein thrombosis?

poor blood flow

sitting for long periods of time

 

 

4

What are the symptoms of deep vein thrombosis?

Swelling and heat in leg

Very painful

5

What can result from a failure to treat deep vein thrombosis?

Loss of a leg

6

Which two things can increase clotting?

  • Replacement factors (VIII & IX)
  • Plasminogen ihibitors

7

Which enzyme does waraffin inhibit?

Vitamin K reductase

(stops carboxylation of glutamic acid residues = cannot bind platelet = no proteolysis = no cascade and no clotting)

8

Which 3 drugs increase the action of waraffin and how?

  • Aspirin = displace it from plasma proteins
  • Sulphonamides = interferes with liver function
  • NSAIDs = interferes with platelet function

9

Which two patient factors increase the action of waraffin?

  • Liver disease (decreases factor production and clearance)
  • Reduced vitamin K availiability

10

What is the average rate of onset for warrafin use?

12-16 hours

11

How long do the effects of warrafin last once you stop taking it?

4-5 days

12

How do we measure the action of warrafin in a patient?

Prothrombin time

(the time a sample takes to clot following addition of a standardised amount of Ca = ratio = compared to healthy subjects)

 

2-2.5 = prophylaxis of deep vein thrombosis

2.5 = treatment of deep vein thrombosis/ pulmonary embolism

3.5 = recurremt deep vein thrombosis/pulmonary embolism

 

13

After starting a patient on warrafin at which intervals do we measure the action of warrafin?

Initially daily

Then at longer intervals

Then every 12 weeks

14

Which two drugs decrease the action of warrafin and how?

  • Barbituates = induce metabolising enzymes
  • Colestipol (athlerosclerosis) = decreases absorption

15

Which two patient factors decreases the action of warrafin?

  • Increased vitamin K = promoted clotting factor synthesis
  • Vomitting

16

What are the side effects of Warrafin (2)?

  • Haemorrhage in bowel or brain (stop administration & give vitamin K & replacement factors)
  • Teratogenic (damages foetus)

17

Name two injectable anticoagulants:

Heparin

Low molecular weight heparin

18

Which two factors does heparin hit?

Factor IIa 

Factor Xa

= activates antithrombin III 

n.b. Heparin also binds to factor IIa but LMW heparin is too short = only hits factor Xa!!

 

19

What is the main clinical use for heparin?

Clearing blocked IV catheters

20

What inhibits heparin?

Factor IV (LMW heparin not inhibited)

21

Can factor Xa bind to factors already bound to fibrin?

No

22

What causes heparin to be badly absorbed in the gut?

Its large size and charge

23

In which 2 ways can heparin be administered?

IV 

Subcutaneous (LMW heparin only)

24

Why is there an initial rapid removal of heparin?

Binds to plasma proteins (heparin only), endothelial cells and macrophages

 

25

How is heparin excreted?

Slowly through renal excretion

26

What are the side effects of heparin (5)?

  • haemorrhage (counter with heparin antagonist e.g. protamine sulphate)
  • Thrombosis (rare -> when antibodies against heparin cause endothelial damage)
  • Osteoporosis
  • Hypersensitivity
  • Hypoaldosteronism

27

Name 4 examples of heparin:

heparin

calciparine

minihep

monoparin

28

Name 3 types of LMW heparin:

Certoparin

Dalteparin

Enoxaparin

29

Name 3 antithrombin independant anticoagulants:

  • Hirudin (binds thrombin active site -> leeches)
  • Hirugen
  • Bivalirudin

30

Which patients may antithrombin III independant anticoagulants be useful for?

Those who produce heparin antibodies