Drugs

Question 1

How does heparin work?

Answer 1

It potentiates anti-thrombin.

Question 2

What reveres heparin?

Answer 2

Protamine sulphate.

Partial reversal for LMWH

Complete reversal for unfractionated .

Question 3

Low molecular weight heparin only acts on what?

Answer 3

Only acts on factor Xa. e.g. dalteparin.

Question 4

Unfractionated inhibits what factors?

Answer 4

2, 9, 10, 11, 12

Question 5

In general, LMWH is favoured over unfractionated due to it having a longer half life and a narrowed therapeutic activity making it more predictable.

Answer 5

…

Question 6

How do you monitor LMWH?

Answer 6

Factor Xa assay.

Question 7

How do you monitor unfractionated heparin?

Answer 7

APTT.

Question 8

What factors does warfarin act on?

Answer 8

2, 7, 9, 10 (protein C and Protein S)

Warfarin antagonises vitamin K so therefore produces non functioning derivatives of factors 2, 7, 9 and 10.

Question 9

When should the dose of warfarin be taken?

Answer 9

Should be taken at the same time everyday (6pm recommended)

Question 10

How is the INR calculated?

Answer 10

Patients PT in seconds / Mean normal PT in seconds.

Question 11

How does dabigatran work?

Answer 11

Direct thombin inhibitor

Question 12

How do rivaroxaban and apixaban work?

Answer 12

Factor Xa inhibitor

Question 13

Platelets bind to subendothelial collagen via what?

Answer 13

Via glycoproteins and Von Willebrand factor

Question 14

Platelets attach to each other via what?

Answer 14

Via GPIIbIIIa and fibrinogen

Question 15

How does aspirin worj?

Answer 15

Inhibits Cyclooxygense which is necessary to produce thromboxane A2.

Question 16

2 side effects of aspirin?

Answer 16

1) Bleeding
2) Blocks production of prostaglandins

GI ulceration and bronchospasm

Question 17

How do clopidogrel and prasugrel work?

Answer 17

Both are ADP receptor antagonists.

Question 18

How does dypiradmole work?

Answer 18

Phosophdiesterase inhibitor - reduces production of cAMP which is a second messenger in platelet activation .

Question 19

When should heparin be stopped before surgery?

Answer 19

The night before

Question 20

Warfarin effects on coagulation times?

Answer 20

Increased PT and APTT.
No change in thrombin time.
Increased PT is much more profound than the APTT.

Question 21

INR warfarin targets?

Answer 21

2-3 for DVT, PE, AF

3-4 for VTE on warfarin, metallic heart valve, antiphospholipid syndrome

Question 22

When should you stop warfarin before surgery?

Answer 22

5 days.

Question 23

Management of major bleeding when on warfarin?

Answer 23

• Stop warfarin.
• Give IV vitamin K (slow IV injection)
• Give dried prothrombin complexes (II, VII, IX, X)

Recombinant factor VIIa is not recommended.

Question 24

Management of INR > 8.0 with no bleeding?

Answer 24

Stop warfarin.
Give ORAL vitamin K.
Repeat dose after 24 hours if INR still too high.
Restart warfarin when INR < 5.0

Question 25

Management of INR >8.0 with minor bleeding?

Answer 25

Stop warfarin
Give IV vitamin K. (Slow IV injection)
Start warfarin when INR <5.0

Question 26

Management of INR 5.0-8.0 with no bleeding?

Answer 26

Withhold 1 or 2 doses of warfarin and reduce subsequent maintenance doses.

Question 27

Management of INR 5.0-8.0 with minor bleeding?

Answer 27

Stop warfarin sodium.
Give vitamins K by slow IV injection.
Restart warfarin when INR < 5.0.

Question 28

How do you cut someone’s warfarin down if their INR is too high?

Answer 28

In general, changing the dose by 15% is expected to result in a change in INR of 1.

10% change anticipated to result in INR of 0.7-0.8

Question 29

What drugs potentiate the action of warfarin?

Answer 29

Antibiotics
Omeprazole
Alcohol

Question 30

What drugs reduce the effect of warfarin?

Answer 30

Phenytoin
Carbamazepine
Rifampacin.