Heparin

Question 1

Where is heparin found in the body?

“BE SPECIFIC.”

Answer 1

They are found in the mast cells of the lungs // liver // intestinal mucosa.

Question 2

What is the charge of a heparin molecule?

Answer 2

Negative.

Question 3

By how much does heparin INCREASE anti-thrombin activity?

Answer 3

By x2,000 to x10,000

Question 4

What components does heparin act on?

Answer 4

Antithrombin
Thrombin
IXa
Xa
XIa

Question 5

What is the purpose of heparin?

Answer 5

It is a blood thinner = Known as an anticoagulant.

Question 6

What type of site does anti-thrombin have?

Answer 6

Positively charged LYSINE sites.

Question 7

What happens when heparin binds to anti-thrombin?

Answer 7

A conformational change in anti-thrombin occurs.

Question 8

What does Factor IIa need to bind to in order form a complex?

Answer 8

Needs to bind to active site of arginine and heparin in order to form a complex.

Question 9

What happens after a factor IIa complex is formed?

Answer 9

Removed by an endothelial system.

Then, heparin leaves (INTACT) in order to bind to more in the future.

Question 10

What is the key difference for Factor Xa when it’s binding in order to form a complex?

Answer 10

Heparin ONLY needs to react with anti-thrombin.

Question 11

What is fractionation?

Answer 11

This is when unfractionated heparin is MODIFIED in order to reduce the size of polysaccharide chains.

Question 12

What is the name given for heparin molecules which undergo fractionation?

Answer 12

Low molecular weight heparin (LMWH).

Question 13

Name the 3 main LMWH products used commercially.

Answer 13

Enoxaparin
Tinzaparin
Dalteparin

Question 14

How is enoxaparin formed?

Answer 14

Benzylation followed by alkaline depolymerisation.

Question 15

How is tinzaparin formed?

Answer 15

Enzymatic depolymerisation.

Question 16

How is dalteparin formed?

Answer 16

Nitrous acid depolymerisation.

Question 17

What is the mean molecular weight of LMWH molecules?

Answer 17

4 - 5 kDa.

Question 18

What is the mean molecular weight of unfractionated heparin?

Answer 18

10 - 40 kDa.

Question 19

Which out of UFH and LMWH has the higher bioavailability?

Answer 19

LMWH

Question 20

What is the main route of administration for unfractionated heparin?

Answer 20

Intravenous Infusion

Question 21

What is the main route of administration for LMWH?

Answer 21

Subcutaneous Injection

Question 22

What is the half life for LMWH?

Answer 22

4 - 6 hours -> thus, has a SLOWER renal clearance.

Question 23

What is heparin induced thrombocytopenia?

Answer 23

This is the development of a LOW platelet count.

Question 24

Where is LMWH metabolised?

Answer 24

The liver.

Question 25

What happens to the duration and effect when the dosage shifts from low to therapeutic?

Answer 25

There is an increase in duration and effect.

Question 26

By how much is the effect of subcutaneous injection delayed?

Answer 26

1 - 2 hours.

Question 27

What is the difference in terms of duration between iv and sc administration?

Answer 27

Subcutaneous injection is short term compared to iv infusion.

Question 28

What is thromboprophylaxis?

Answer 28

This is a medical treatment to prevent development of thrombosis.

Question 29

What is APTT?

Answer 29

It is blood test which characterises coagulation of the blood. Thus, measures how LONG it takes for a clot to form.

Question 30

What is ACT?

Answer 30

This measures the activated clotting time.

Question 31

What is reflected by the administration of anti Xa?

Answer 31

Reflects the concentration of heparin in the patients plasma.

Question 32

When is monitoring required in terms of administering Anti Xa?

Answer 32

When the patient has: - Extreme Body Weight - Renal Impairment

Question 33

What are the 4 adverse reactions of heparin treatment?

Answer 33

HIT Osteopenia Injection Site Reactions Bleeding

Question 34

What is HIT?

Answer 34

This is when there is a LOW platelet count.

Question 35

What is the scoring system for HIT?

Answer 35

4T scoring system = 2 points per factor. - Thrombocytopenia - Thrombosis - Timing - Other causes of thrombocytopenia

Question 36

What are the other causes of thrombocytopenia?

Answer 36

Septicaemia

Question 37

What happens if the HIT score is greater than 4?

Answer 37

Heparin is stopped and instead an alternative anticoagulant is given.

Question 38

What is an alternative anticoagulant given?

Answer 38

Argatroban

Question 39

What is the optimal timing for viewing the results of heparin administration?

Answer 39

5 days after starting heparin.

Question 40

Why can heparin induced thrombocytopenia (HIT) occur?

Answer 40

This is due to the body producing an IgG antibody towards heparin.

Question 41

What is osteopenia?

Answer 41

This is the thinning of the bones due to dose and duration.

Question 42

What can occur due to injection site reactions?

Answer 42

Bleeding Ecchymosis Erythema Skin Necrosis

Question 43

What is ecchymosis?

Answer 43

Easier bruising

Question 44

What is erythema?

Answer 44

Redness of the skin

Question 45

In terms of bleeding, which type of heparin produces LESS bleeding as an adverse reaction?

Answer 45

LMWH.

Question 46

What partially reverses LMWH?

Answer 46

Protamine.

Question 47

What are the side effects of taking protamine?

Answer 47

Hypotension | Bradycardia

Question 48

Who can't take protamine?

Answer 48

Those allergic to fish as it's made from fish sperm.