Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MD2002 Lucas > Anticoagulant Drugs > Flashcards

Anticoagulant Drugs Flashcards

1
Q

What is haemostasis ?

A

The arrest of blood loss from damaged blood vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the main ways in which haemostasis occurs.

A
  • Vascularconstriction
  • Formation of a platelet plug
  • Formation of a blood clot as a result of blood coagulation
  • Growth of fibrous tissue into the blood clot to close the hole permanently
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Is promotion of haemostasis ever necessary ? Using what drug ?

A

Rarely, using tranexamic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Which steps of thrombosis does drug therapy target ?

A
  • Blood clotting
  • Platelet adhesion and activation
  • Processes involved in fibrin removal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Identify an example of condition due to genetically determined deficiencies of clotting factors. How is this condition treated ?

A

Haemophilia

Treated with replacement therapy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are possible causes of acquired clotting defects ? How are these treated ?

A

Liver Disease
Vitamin K deficiency
Ingestion of oral anti-coagulants

Treated with

  1. natural Vitamin K (phytomenadione) or
  2. synthetic preparation, menadiol sodium phosphate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the role of vitamin K in the treatment of clotting defects ?

A

Acts as co-factor for “the gamma-carboxylase enzymes which catalyze the posttranslational gamma-carboxylation of glutamic acid residues in inactive hepatic precursors of coagulation factors II (prothrombin), VII, IX and X”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are all the clinical uses of vitamin K ?

A
  • Treatment and/or prevention of bleeding from excessive oral anticoagulant use
  • In babies to prevent haemorrhagic disease of the newborn
  • For Vitamin K deficiencies in adults
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Identify antagonists of vitamin K.

A

Warfarin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does warfarin inhibit vitamin K action ?

A

Prevents reduction of vitamin K

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the onset of warfarin ? Why ?

A

Takes many hours to act because of time taken for degradation of factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How may one cover for the slow onset of warfarin ?

A

Using heparin treatment

Giving loading dose of warfarin then go down to small dose to try and maintain plasma levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the main side effect of warfarin ? How can this be treated ?

A

haemorrhage

Can be reversed by Vitamin K

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How are patients’ response to the dose of warfarin measured ?

A

Prothrombin Time test, allows to calculate International Normalized Ratio (INR)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Identify factors which increase the effect of warfarin.

A
  • ↓ availability of Vitamin K
  • Broad-spectrum antibiotics
  • Liver disease
  • Drugs which:
  • impair platelet function
  • displace warfarin from their binding sites on plasma albumin
  • agents which inhibit microsomal enzymes in the liver

-Dietary factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Identify factors which decrease the effect of warfarin.

A
  • Drugs which ↑ drug metabolism
  • Oral contraceptives
  • Dietary factors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the method of administration of warfarin ?

A

Orally

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the method of administration of heparin ?

A

Injected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Give an example of heparin.

A

Dalteparin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What kind of molecule are heparins ?

A

sulphated glycosaminoglycans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the main two groups of heparin ? What is their main distinction ?

A

Unfractionated (UFH) or Low Molecular Weight (LMWH)

LMWH longer acting, don’t require monitoring

22
Q

Where is heparin found in the body ?

A

In mast cells, in plasma and in endothelial cells

23
Q

What is the onset of heparin ?

A

Starts acting almost immediately

24
Q

What is the main side effect of heparin ?

How can this be treated ?

A

Haemorrhage

May be reversed by protamine

25
Q

What is the mechanism of action of heparin ?

A
  • Antithrombin forms a 1:1 complex with thrombin by binding to active site, thus inhibiting thrombin
  • Heparin acts on antithrombin III (naturally-occurring inhibitor of thrombin) and other serine proteases in the coagulation cascade (XIIa, XIa, IXa, & Xa) (brings ATIII to activated factors)
  • As a result, heparin accelerates the rate of this inhibition (thus prevents fibrin formation)
26
Q

Which chemical property of heparin relates to its mechanism of action in preventing blood clotting ?

A

Electronegative charge

27
Q

Identify two direct factor Xa inhibitors ?

A

Rivaroxaban or apixaban

28
Q

What is the route of adminsitration of direct factor Xa inhibitors ?

A

Orally

29
Q

How is response to direct factor Xa inhibitors measured ?

A

Does not require PT/INR monitoring (Meaningless for these drugs!)

30
Q

What is the onset of direct factor Xa inhibitors ?

A

Rapid onset of action compared to warfarin, just takes a few hour

31
Q

What is the duration of effect of direct factor Xa inhibitors ? How long does it take before factor Xa normal activity comes back to normal ?

A

8-12 hours

24 hours

32
Q

What is the main side effect of direct factor Xa inhibitors ? How is this treated

A

Haemorrhage

No antidote

33
Q

Are anti-platelets and anti-coagulants the same ?

A

No

34
Q

Identify two examples of anti-platelet drugs.

A

Aspirin

Clopidogrel

35
Q

How do aspirin and Clopidogrel respectively inhibit platelet

A

ASPIRIN
Inhibits cyclooxegenase
Stops production of thromboxanes which would normally increase expression of receptors that lead to aggregation

CLOPIDOGREL
Inhibits P2Y12 purinergic receptors
Inhibits ADP-induced platelet aggregation

36
Q

What is the general function of Antiplatelet drugs ?

A

Decrease platelet aggregation and thereby inhibit thrombus formation

37
Q

What is Fibrinolysis ?

A

Breaking down of thrombus

38
Q

When is fibrinolysis induced ?

A

When the intrinsic coagulation system is activated

39
Q

Describe the mechanism of fibrinolysis.

A
  • Generation of plasminogen activators
  • Plasminogen activators release active enzyme plasmin from plasminogen precursor
  • Plasmin digests not only fibrin but other blood proteins such as factors II, V & VII
40
Q

What is plasminogen ?

A

Inactive pro-enzyme deposited in the fibrin strands within a thrombus

41
Q

What is plasmin ?

A

Trypsin-like enzyme acting on ARG-LYS bonds

42
Q

How is plasmin which escapes into circulation removed after having fulfilled its function ?

A

Plasmin which escapes into the circulation is inactivated by various plasmin inhibitors

43
Q

Give examples of fibrinolytic agents.

A

Streptokinase, Alteplase

44
Q

What kind of organic molecule is streptokinase ?

A

Non-enzymatic protein

45
Q

How does streptokinase lead to fibrinolysis ?

A

Acts indirectly by forming a stable complex with plasminogen. This activates enzymatic activity of plasminogen by inducing a conformational change.

46
Q

Give an example of Tissue Plasminogen Activator. How is this plasminogen activator synthesised ?

A

ALTEPLASE

Synthesised in vivo by endothelial cells, but can also be made by recombinant technology

47
Q

How is Alteplase clot selective (does not just activate plasminogen in the plasma) ?

A

Because Alteplase’s enzymatic activity is enhanced more in the presence of fibrin-bound plasminogen than plasma plasminogen

48
Q

Overall, what are the main groups of drugs which target thrombosis ? What process does each of these inhibit/activate ?

A
  1. Anticoagulants (Heparin, Warfarin, Factor Xa inhibitors): Inhibits activation of clotting factors (XIIa, IXa, XIa, Xa)
  2. Antiplatelet agents (Aspirin, Clopidogrel): Inhibits platelet adhesion, activation, aggregation
  3. Fibrinolytic agents (Streptokinase, Alteplase): Enhances conversion of Plasminogen into Plasmin (which digests fibrin and blood proteins)
49
Q

What are some therapeutic uses of anticoagulants ?

A

VENOUS THROMBOEMBOLISM

TREATMENT AND PROPHYLAXIS OF
– DVT
– Pulmonary embolisms
– Thromboembolism from atrial fibrillation 
– Prosthetic heart valves
– Clotting during kidney dialysis
50
Q

What specific anticoagulants are given for venous thromboembolisms ?

A

– Heparin for short-tem action

– Oral anticoagulants for prolonged therapy

51
Q

What are some therapeutic uses of antiplatelet agents and fibrinolytic agents ?

A

FIBRINOLYTIC AGENTS + ASPIRIN
-therapy of acute myocardial infaraction (within 4-6 hours of onset)

ASPIRIN
-can reduce the risk of occlusive cardiovascular disease in patients already diagnosed as being at risk

MD2002 Lucas (111 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions