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Year 3 - Pharmacology > Anti-coagulants > Flashcards

Flashcards in Anti-coagulants Deck (12)
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1
Q

what is the MOA of UH? of LMWH?

A

UH:

  1. forms complex between anti-thrombin III and thrombin - inactivates thrombin
  2. increase anti-thrombin III activity against factor Xa

LMWH:
1. increase anti-thrombin III activity against factor Xa

2
Q

name examples of LMWH

A

dalteparin, enoxaparin, tinzaparin

3
Q

how are heparins administered?

A

UH: IV bolus + IV infusion
LMWH: S/C injection

4
Q

name characteristic side effects of heparin

A
  1. bleeding
  2. hyperkalaemia (inhibition of aldosterone secretion)
  3. heparin-induced thrombocytopenia (autoimmune reaction as heparin is immunogenic) - less with LMWH
  4. osteoporosis (long-term use) - less with LMWH
5
Q

how would you monitor UH and LMWH use? how would you reverse effcts if required?

A

UH:

  • APTT ratio (check 6 hrs after dose change and 24 hourly once pt established within therapeutic range)
  • check platelet count regularly between day 5-14

LMWH:
- anti-Xa assay - not required routinely

Reversal: protamine sulphate (only partially effective in LMWH)

6
Q

what is the MOA of warfarin?

A

inhibits vitamin K epoxide reductase… inhibits production of vitK-dependent clotting factors (II, VII, IX and X)

7
Q

name common ADRs of warfarin

A
  1. bleeding

2. teratogenic

8
Q

what can interfere with warfarin action?

A
  • vitK found in health foods, supplements, large amounts of leafy green veg or green tea
  • pomegranate - increased INR in response to warfarin
9
Q

which parameters should be monitored with warfarin use?

A
  1. baseline PT

2. INR measured daily in early days of Tx, then at longer intervals, then up to 12 wks

10
Q

what is target INR for the different indications of warfarin?

A

INR 2.5 for:

  • DVT or PE
  • AF or cardioversion
  • dilated cardiomyopathy
  • MI
  • bioprosthetic valve

INR 3.5 for:

  • recurrent DVT or PE
  • mechanical valve
11
Q

how would you reverse warfarin therapy if:

  1. INR <8 and no/minor bleeding
  2. INR >8 and no/minor bleeding
  3. major bleeding
A
  1. stop warfarin (restart when INR <5)
  2. stop warfarin (restart when INR <5) and give 0.5-2.5 mg oral vitK if other bleeding risk factors present
  3. stop warfarin, give PT complex concentrate or FFP and give 5 mg oral/IV vitK
12
Q

describe the MOA of the different DOACs

A
  • dabigatran: direct competitive thrombin inhibitor

- apixaban/rivaroxaban/edoxaban: factor Xa inhibitors