Anticoagulant Drugs Flashcards

1
Q

what are indications for anticoagulant drugs

A

venous thrombosis

atrial fibrillation

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2
Q

what is the mechanism of action of heparin and how can it be taken

A

Potentiates antithrombin
Immediate effect - can be given in acute situations

IV or sc

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3
Q

what are the 2 forms of heparin

A

unfractionated

LMWH

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4
Q

how does LMWH differ from unfractoinated heparin in terms of mode of action

A

unfractionated = more suited too Anti Thrombin and thrombin.

LMWH = more suited to Anti Thrombin and factor X

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5
Q

what is used to monitor heparin

A

APTT

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6
Q

when would more monitoring of a patient on heparin be considered

A

Hx of kidney disease

- heparin is cleared through the kidneys

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7
Q

what are complications of Heparin

A

bleeding

Heparin induced thrombocytopenia (with thrombosis) = HITT

osteoporosis

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8
Q

what happens in HITT

A

can develop anti bodies to heparin&raquo_space;> leading to thrombocytopenia
occurs between 5-10 days of starting heparin

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9
Q

how would you monitor for HITT

A

need to monitor FBC = if you see platelet count drop between 5-10 days

would need to stop the drug

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10
Q

what is the antidote to heparin

A

protamine sulphate

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11
Q

what else can be done if you need a heparin reversal

A

stop heparin

- has a short half life, particularly unfractionated [only 30 mins]

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12
Q

what are features of vitamin K - where is it absorbed

A

Fat soluble vitamin

Absorbed upper intestine

Requires bile salts for absorption

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13
Q

what is vitamin K needed for

A

Final carboxylation of clotting factors II, VII, IX and X

Protein C and S

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14
Q

what is first affected when warfarin is given

A

Protein C and S

- have a much shorter half life than clotting factors

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15
Q

what does vitamin K do

A

adds COOH group to clotting factors that make it possible for them to bind through calcium to the phospholipid platelet

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16
Q

how does warfarin work

A

blocking the ability of Vitamin K to carboxylate the Vitamin K dependent clotting factors, thereby reducing their coagulant activity

17
Q

what is the name for the MOA of warfarin

A

antagonism of vitamin K

causing synthesis of non functional coag factors

18
Q

where is warfarin metabolised and what can interfere with this

A

liver

alcohol metabolised by the same enzyme

19
Q

what is the INR window we aim for with warfarin treatment

A

INR 2-3

above = risk of bleeding
below = not doing anything useful
20
Q

what is INR

A

standardisation of PT across labs

21
Q

what are complications of warfarin

A

Haemorrhaging

- beware drug interactions

22
Q

what are bleeding complications seen in warfarin therapy

A

mild
- skin bruising, epistaxis, haematuria

severe

  • GI, intracerebral
  • would see significant drop in Hb
23
Q

how can warfarin actions be reversed

A

1-2mg oral vitamin K
- reveres affects in 6 hours

IV clotting factors
- reveres affects immediately

24
Q

what are new anti-coagulants

A

Thrombin inhibitors
- e.g. Dabigatran

Xa inhibitors
- e.g. Rivaroxaban, Apixaban

25
Q

what is Rivaroxaban starting to be used first line in

A

AF

DVT, PE

26
Q

why are new anticoagulants starting to be preferred

A

taken orally
no monitoring required
less drug interactions

27
Q

how can warfarin be taken

A

IV or oral

28
Q

what are drawbacks of the new anticoagulants

A

no specific antidote