11. Drugs influencing Haemostasis: Anti-coagulants

Question 1

What do drugs target in thrombosis?

Answer 1

Blood coagulation  (anti-coagulants drugs)
Platlet function 
Enhance fibrin breakdown

Question 2

Coagulation cascade….?

Answer 2

Target of anticoagulant drugs

Question 3

Examples of anticoagulant drugs?

Answer 3

Heparin
-unfractioned (UFH)
-Low molecular weight (LWMH)
Coumarins (warfarin)
Non-vitamin K oral anticoagulants

Question 4

What are the two types of heparin?

Answer 4

Family of glycosaminoglycans of variable chain length (UFH)

Fractionated into low-molecular weight heparin (LMWH)

Question 5

Mechanism of action of heparin…

Answer 5

XX

Question 6

Why can heparin not be absorbed by the GIT?

Answer 6

They are large and highly charged molecules

Question 7

How is UFH given?

Answer 7

Intravenously therefore immediately active

Question 8

How is LMWH given?

Answer 8

Subcutaneously takes longer to get into blood

Question 9

What are the uses of LMWH heparin?

Answer 9

Treatment of thromboemoblic disease intially together with warfarin

Prevention of thromboemobolic disease

Extracorporeal circuits

Question 10

What are the adverse effects of heparin?

Answer 10

Haemorrhage (bleeding gums)
Reduced aldosterone secretion/hyperkalaemia
Rarely osteoporosis and alopecia
Hypersensitivity reactions
Thrombocytopenia (reduced platelet count)

Question 11

How is UFH heparin monitored?

Answer 11

Lab monitoring is essential - determination of the activated partial thromboplastin time

Question 12

What does APTT stand for?

Answer 12

Activated partial thromboplastin time

Question 13

Does LMWH affect APTT?

Answer 13

No

Question 14

Warfarin mechanism of action/

Answer 14

XX

Question 15

Uses of warfarin

Answer 15

Prophylaxis and treatment of thromboembolic disease
Propylaixs in atrial fibrilation
Prophiylaxis with prosthetic heart valves fitted

Question 16

Adverse effects of warfarin?

Answer 16

Haemorrhage/High INR
GI upset
Teratogeen 
Alopecia 
Skin necrosis

Question 17

Contraindications of warfarin

Answer 17

Pregnancy 
active bleeding 
Peptic ulcer 
Uncontrolled severe hypertension 
Bacterial endocartitis

Question 18

What drugs increase warfarins effect?

Answer 18

Alcohol and cranberry juice
Most anitbiotics
Azole antifungals
Cimetidine

Enzyme inhibitors

Question 19

What drugs decrease warfarins effect?

Answer 19

Enzyme inducers

Rifampicin
Barbituates
Anti-epileptics

Question 20

Clinical use of direct acting anticoagulants

Answer 20

Treatment of DVT/PE
Prophylaxis of DVT/PE
Prophylaxis of stroke in non-valvular atrial

Question 21

Side effects in direct acting oral anticoagulants

Answer 21

GI upset 
Abdominal pain 
Dyspepsia 
Thrombocytopenia 
Haemorrhage

Question 22

Why use non- vitamin K oral anticoagulants?

Answer 22

Shorter duration of action, reduced risk of haemorrhage

Question 23

Advantages of non-vitamin K oral anticoagulants?

Answer 23

orally available
no need for monitoring INR (but still need to monitor patient and other blood tests!!)
less toxicity, fewer drug interactions

Question 24

Disadvantages of non-vitamin K oral anticoagulants?

Answer 24

lack of INR means no way of confirming drug adherence – important as NOACs have direct action and short half-life
less known yet about efficacy and safety
lack of reversal agents?

Question 25

Look at LOs

Answer 25

XX