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C. Year 3: Core Drugs > Anti-coagulant Heparin fractionated (LMWH) > Flashcards

Anti-coagulant Heparin fractionated (LMWH) Flashcards

1
Q

Do anticoagulants act on primary or secondary haemostasis?

A
  • secondary haemostasis
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2
Q

What is the purpose of the coagulation cascade?

1 - accentuate primary haemostasis
2 - convert fibrinogen into fibrin
3 - inhibit platelets activation in primary haemostasis

A

2 - convert fibrinogen into fibrin

  • fibrinogen = factor 1
  • fibrin = 1a
  • fibrin are monomers that form crosslinks and a strong clot
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3
Q

The coagulation cascade has 3 parts, intrinsic, extrinsic and common pathways. How is the intrinsic pathway started?

1 - factor XII (12) comes into contacts with collagen or activated platelets
2 - factor X (10) binds with fibrin
3 - factor XII (12) binds von willebrand factor
4 - factor XII (12) binds inactive platelets

A

1 - factor XII (12) comes into contacts with collagen or activated platelets

  • platelets are activated from primary haemostasis
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4
Q

Once the intrinsic pathway has begun by factor XII (12) binding with activated platelets or collagen, what then happens in the intrinsic pathway?

1 - factor XII (12) then becomes factor X (10)
2 - activated platelets activate factor XI
3 - factor XII (12) becomes factor XIIa (12a) and activates factor XI (11), then IX (9) and then X (10)
4 - collagen activates factor XI (11)

A

3 - factor XII (12) becomes factor XIIa (12a) and activates factor XI (11), then IX (9) and then X (10)

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5
Q

In the intrinsic pathway, which factor activates the common pathway?

1 - factor XIIa (12a)
2 - factor XIa (11a)
3 - factor IX (9)
4 - factor Xa (10a)

A

4 - factor Xa (10a)

  • Xa (10a) then activates factor II (2) called thrombin
  • factor II (2) called thrombin then activates factor I (1) which builds the fibrin mesh
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6
Q

Once the common pathway has been activates by factor Xa (10) it activates factor II (2 thrombin) which activates factor Ia (1a, called fibrin) which begins building fibrin. Which 4 other cofactors is factor IIa (2a thrombin) able to also activate?

1 - Ia (1a), IIIa (3a), IVa (4a) and V (5a)
2 - XIa (11a), IIIa (3a), IVa (4a) and VIIa (7a)
3 - IIIa (3a), IVa (4a), Va (5a) and XIIa (12a)
4 - Va (5a), VIIIa (8a), IXa (9a) and XIIIa (13a)

A

4 - Va (5a), VIIIa (8a), IXa (9a) and XIIIa (13a)

  • Va (5a) acts as a cofactor for factor Xa (10a)
  • VIIIa (8a) acts as a cofactor for factor IXa (9a)
  • IXa (9a)
  • XIIIa (13a) helps factor I (1a) called fibrin form crosslinks and a stronger clot
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7
Q

The extrinsic pathway is activated when factor VIIa (7a) binds with what on exposed tissue?

1 - von Willebrand factor
2 - tissue factor
3 - tissue plasminogen factor
4 - protein C

A

2 - tissue factor

  • factor VIIa (7a) then activates the factor Xa (10a) and the common pathway
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8
Q

In secondary haemostasis, which factor is often referred to as the accelerator due to its multiple procoagulating functions?

1 - factor IIa (2a)
2 - factor Xa (10a)
3 - factor Va (5a)
4 - factor Ia (1a)

A

1 - factor IIa (2a)
- also referred to as thrombin

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9
Q

Thrombin (factor IIa (2a) is able to do lots of things involved in coagulation. It does all of the following EXCEpt which one?

1 - binds platelets activating them
2 - activates factor Va (5a)
3 - activates factor VIIIa (8a)
4 - converts fibrinogen (factor I (1) into fibrin (factor Ia (1a))
5 -converts factor XIII (13) into factor XIIIa (13a) that binds with Ca2+ cofactor forming cross bridges between fibrin mesh
6 - activates protein C and S

A

6 - activates protein C and S

  • proteins S and C ensure clotting does not go into overdrive
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10
Q

Factor IIa (2a) also called thrombin is one of the key cofactors in secondary haemostasis. What is the bodies natural molecule that aims to modulate the activation of thrombin?

1 - protein S
2 - protein C
3 - antithrombin (factor IIIa (3a))
4 - factor Va (5a)

A

3 - antithrombin (factor IIIa (3a))

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11
Q

Factor IIa (2a) also called thrombin is one of the key cofactors in secondary haemostasis. Antithrombin (factor IIIa (3a)) is the bodies naturally produced modulator of thrombin. Which 2 key factors in the common pathway is antithrombin (factor IIIa (3a)) able to bind with and reduce coagulation?

1 - factors Va (5a) and Xa (10a)
2 - factors IIa (2a) and Xa (10a)
3 - factors XIIIa (8a) and Xa (10a)
4 - factors IIa (2a) and XIIIa (13a)

A

2 - factors IIa (2a) and Xa (10a)

  • this essentially inhibits or reduces the activity of the common pathway
  • factor Xa converts prothrombin into thrombin (factor IIa (2a))
  • remember 2 = 7 = 9, 10, 11, 12
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12
Q

Which factors overall is anti-thrombin (IIIa (3a)) able to bind with and inhibit?

1 - factors 1, 2, 3, 4 and 5
2 - factors 2, 7, 9, 10, 11 and 12
3 - factors 1, 2, 7, 9 and 10
4 - factors 5, 7, 9, 11, 13

A

2 - factors 2, 7, 9, 10, 11 and 12

  • remember 2 = 7 = 9, 10, 11, 12
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13
Q

In secondary coagulation the extrinsic pathway is started when damaged endothelial cells release factor III (tissue factor III) which binds with the active factor VIIa (7a) and Ca2+. This then forms the VIIa-TF complex on the smooth muscle of blood vessels. The VIIa-TF complex then cleaves what factor?

1 - factor II (2 or prothrombin)
2 - factor X forming Xa
3 - factor VIII (8)
4 - factor V (5)

A

2 - factor X forming Xa

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14
Q

Once factor Xa has become active due to the extrinsic pathway, what factor does Xa (10a) and Ca2+ bind with that will then go onto form the prothrombinase complex?

1 - factor II (2 or prothrombin)
2 - factor I (1)
3 - factor VIII (8)
4 - factor V (5)

A

4 - factor V (5)

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15
Q

Once the prothrombinase complex has been formed by active factors X (10) and V (5), what does this then cleave in the extrinsic pathway?

1 - factor II (2 or prothrombin)
2 - factor I (1)
3 - factor VIII (8)
4 - factor XII (12)

A

1 - factor II (2 or prothrombin)
- prothrombin becomes thrombin (IIa)

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16
Q

Which pathway of the coagulation cascade doe the prothrombin time (PT), which is essentially the time it takes to form a clot measures?

1 - common
2 - extrinsic
3 - intrinsic

A

2 - extrinsic pathway

  • essentially this is the time it takes to form a clot
  • tissue factor (III), Ca2+ and factor VII (7) form complex and active factor X (10)
  • factor X (10) binds factor V (5) and Ca2+ and cleaves prothrombin into thrombin, which is where the name prothrombin time comes from
17
Q

What is the normal value for prothrombin time (PT), which is essentially the time it takes to form a clot?

1 - 0.1 - 1.4 secs
2 - 1-4 secs
3 - 10-14 secs
4 - 15-20 secs

A

3 - 10-14 secs

18
Q

In the coagulation cascade, activated partial thromboplastin time (aPTT) is a measure of which aspect of the coagulation cascade?

1 - common
2 - extrinsic
3 - intrinsic

A

3 - intrinsic

  • time it takes the intrinsic and common pathway to form a clot following the addition of calcium and phospholipid emulsion in-vitro
19
Q

In the coagulation cascade, activated partial thromboplastin time (aPTT) is a measure of the intrinsic and common pathway to form a clot following the addition of calcium and phospholipid emulsion. What is the normal time for this?

1 - 0.1 - 1.4 secs
2 - 1-4 secs
3 - 10-14 secs
4 - 27-41 secs

A

4 - 27-41 secs

20
Q

What is the international normalised ratio (INR)?

1 - measure of aPTT compared to age and gender matched aPTT
2 - measure of AP
3 - measure of PT as a ratio to a standardised or control PT

A

3 - measure of PT as a ratio to a standardised or control PT

  • PT is a measure of how long it takes clot to form
  • measures extrinsic pathway
21
Q

The international normalised ratio (INR) is a measure of PT as a ratio to a standardised or control PT. What is a normal value for INR?

1 - 0.1 - 1.4
2 - 1-1.3
3 - 10-14
4 - 27-41

A

2 - 1-1.3

22
Q

There is unconjugated (high and low molecular weight) and conjugated heparin (low molecular weight only). The major difference between the 2 is the length of the glycosaminoglycan tails is crucial. Both can bind with antithrombin and increasing its activity against factor Xa (10a). But what can conjugated heparin NOT bind with that unconjugated heparin can bind with?

1 - factor VII (7a)
2 - factor IIa (2a)
3 - factor IIIa (3a)
4 - factor Va (5a)

A

2 - factor IIa (2a)

23
Q

Which of the following is NOT a conjugated heparin (low molecular weight only) that is on our core drug list?

1 - Dalteparin
2 - Dabigatran
3 - Tinzaparin
4 - Enoxaparin

A

2 - Dabigatran

  • this is a DOAC that is able to inhibit thrombin
24
Q

Which of the following are conjugated heparin (low molecular weight only) NOT indicated in?

1 - pulmonary embolism
2 - deep vein thrombosis
3 - acute coronary syndrome
4 - atrial fibrillation

A

4 - atrial fibrillation

25
Q

Dalteparin, Tinzaparin and Enoxaparin are the 3 conjugated heparin (low molecular weight only) core drugs we need to be aware of. What is the mechanism of action of fractionated heparin?

1 - agonist for antithrombin III
2 - activates thrombin
3 - vitamin K antagonist
4 - agonist factor X (10)

A

1 - agonist for antithrombin III

  • only effects factor Xa (10a) though
  • does not have any affect on factor IIa (2a) aka thrombin
26
Q

What method do we use to monitor LMWH?

1 - No monitoring required
2 - INR
3 - APTT
4 - PT
5 - Bleeding time

A

1 - No monitoring required
- typically a safe drug so no need to monitor

27
Q

Which of the following is the major adverse event when prescribing conjugated heparin?

1 - heart failure
2 - oedema
3 - acute kidney injury
4 - haemorrhage

A

4 - haemorrhage

28
Q

Haemorrhage is the major adverse event when prescribing conjugated heparin (low molecular weight only). Which of the following conditions should conjugated heparin not be used in?

1 - immunocomprimised
2 - chronic liver disease
3 - renal impairment
4 - chronic heat failure

A

3 - renal impairment

  • conjugated heparin and fondaparinux both collected in kidneys and can be dangerous
  • must monitor renal function:
    creatinine clearance rates
29
Q

Haemorrhage is the major adverse event when prescribing conjugated heparin. In addition all of the following could occur EXCEPT which one?

1 - bruising at site of injection
2 - hyperkalaemia
3 - oedema
4 - heparin induced thrombocytopenia

A

3 - oedema

  • key side effect to look out for is heparin induced thrombocytopenia
30
Q

Due to drug interactions which class of medications should unconjugated heparin not be prescribed with unless in very specific scenarios?

1 - ACE inhibitors
2 - anti-platelets
3 - loop diuretics
4 - B blockers

A

2 - anti-platelets

  • together they can have an additive effect and further increase the risk of haemorrhage
31
Q

If a patient is taking unconjugated heparin, what is the antidote if they are haemorrhaging?

1 - protamine
2 - naloxone
3 - acetylcysteine
4 - flumazenil

A

1 - protamine

  • naloxone = opiods
  • acetylcysteine = paracetamol overdose in liver
  • flumazenil = diazepam
32
Q

How are heparins generally administered?

1 - orally
2 - SC
3 - IV
4 - suppository

A

2 - SC

33
Q

Although we need to view local guidelines, what would

A

C. Year 3: Core Drugs (125 decks)

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