THINNING THE BLOOD Flashcards
Is the Vitamin K dependant pathway the extrinsic or the intrinsic one?
Extrinsic.
What 4 substances can activate platelets?
Thrombin, ADP, Thromboxane and Collagen
What specific pathway does aspirin block?
The conversion of arachidonic acid into thromboxane
What specific pathway does clopidogrel block?
Block ADP receptors
What drugs are best for preventing venous thrombi?
Anti-coagulants. Heparin and warfarin.
What drugs are best for preventing arterial thrombi?
Anti-platelets drugs. Aspirin and clopidogrel.
Should aspirin be used in primary prevention?
No aspirin is not recommended until an event such as a MI has occurred.
What is the rate of GI bleed with someone on a normal dose of aspirin?
0.1 - 0.5%
Which common anti-platelet agent is actually a pro-drug? What other drug is not recommended when on this anti-platelet agent because it increases the rate at which it is turned into the active agent?
a) Clopidogrel
b) Omeprazole
Post DVT/PE what is the target INR and how long should a patient be on wafarin if this is the first time they have suffered DVT/PE?
a) 2.5
b) 6 months
If someone has a second DVT or PE how long will they need to have warfarin?
For life.
If someone has a DVT/PE whilst their INR is maintained at 2.5 by warfarin, what is the new target INR?
3.5
What is the target INR for someone with a mechanical heart valve?
3.75
List the absolute contraindications of prescribing warfarin. (Name all 5)
Active bleeding Bleeding disorders Recent surgery Space-occupying lesion of CNS 1st trimester and last 4 weeks of pregnancy
If someone was bleeding because their INR became too high following warfarin therapy, what can you give them?
Vitamin K.
Prothrombin complex concentrate (II, IV, IX and X)
Fresh frozen plasma
Which two new oral anti-coagulant (NOAC) drugs inhibit factor X?
Rivaroxaban and Apixaban
What do you give someone to reverse the effects of Rivaroxaban and Apixaban?
You can’t, but the half life is much less than warfarin.
Which new oral anti-coagulant drug (NOAC) cannot be used if the patient has renal problems?
Dabigatran
What drug is normally used for bridging anti-coagulation?
Heparin.
What is bridging anti-coagulation?
A patient on warfarin who comes into hospital for an operation will have the warfarin stopped. Once the INR has decreased they will be started on Heparin which has a short half life so that it can be stopped in time for the surgery.
