Anticoagulants

Question 1

What do you need to inform patients of?

Answer 1

Anticoagulant record - doses/INR targets

Taken at the same time every day ie tea time

If forgotten - if in the same day you remember – take before bed; if forgotten til the next day – omit dose and record in booklet

Some drugs will interfere - tell your doctors (ie NSAIDs, SSRI’s, amiodarone, metronidazole, high dose steroids, aspirin/clopidogrel etc)

Alcohol interferes (increases INR, limit to 2 units max/day)

Food may increase - green leafy veg because vitamin K; cranberry juice to; decrease - avocado, St. John’s wort, green tea, soy beans
Side effects - teratogenic, longer bleeding time, blood in urine/stool

Question 2

How long before surgery would you advise someone to stop taking warfarin?

Answer 2

5 days

INR needs to be <1.5

Can be resumed evening of surgery or next day provided haemostasis is adequate

Question 3

How does warfarin work?

Answer 3

Anticoagulant

Inhibits activation of vitamin K which is necessary for synthesis of clotting factors 10, 9, 7, 2 (1972 mnemonic)

Takes several days to achieve stable INR

Question 4

What are the indications for warfarin?

Answer 4

VTE - target INR = 2.5, 3.5 is repeat VTE

AF - target INR = 2.5

Mechanical heart valves

Question 5

What is INR?

Answer 5

Ratio of prothrombin time for the patient divided by normal prothrombin time

Question 6

What are the side effects of warfarin?

Answer 6

Haemorrhage - strokes

Teratogenic (though can be used in breastfeeding mothers)

Skin necrosis

Question 7

How do you treat an overdose of warfarin?

Answer 7

IV Vit K

Question 8

How do you prescribe for DVT treatment?

Answer 8

Drug: Dalteparin sodium 25 000 unitl/mL injection

Dose: look up different weight ranges in BNF

Route: SC