Anti-coagulants

Question 1

Which is a vit K antagonist ?

Answer 1

Warfarin

Question 2

What is the problem of anti-coagulants having NARROW therapeutic windows?

Answer 2

• over anticoagulation==> bleeding problems

- under: reduced efficacy

Question 3

When are anti-coagulants given?

Answer 3

venous thrombosis

ATRIAL fibrillation

Question 4

Why are anti-coagulants given for atrial fibrillation?

Answer 4

• d.t irregular contraction of the atrium
• results in stasis in the atrium> BLOOD CLOT formed
• —-like venous thrombosis
• risk of STROKE (through common carotid > internal carotid arteries> brain)

Question 5

What are two types of thromboembolic strokes?

Answer 5

• atheroma (platelet rich thrombus)

- embolic stroke if pt HAS Atrial fibrillation —give anticoagulants, check ECG

Question 6

Thrombin role?

Answer 6

• converts fibrinogen to fibrin

- —switching it off; stops coagulation!

Question 7

Why is warfarin effective against PC AND PS?

Answer 7

-they’re also VITK dependant blood clotting factors.

Question 8

How does heparin work?

Answer 8

• causes the blood clot to disappear over a LONG period of time
• —-potentiates anti-thrombin

Question 9

What are the 2 forms of heparin?

Answer 9

• unfractionated (alot of MONITORING) — shorter Half T1/2
• LMWH
• –given as IV / s.c : parentral ! (inpatient)

Question 10

What is the MOA of heparin?

Answer 10

• heparin keeps the anti-thrombin BOUND to thrombin and Xa to potentiate anti-thrombin axn

Question 11

What is the diff between unfractionated and LMWH?

Answer 11

• —–unfractionated keeps anti-thrombin and thrombin together
• —-LMWH - keeps both bound together (Xa and Thrombin) —affect stays for 12-24 hrs

Question 12

How to monitor heparin?

Why does LMWH not require as much monitoring?

Answer 12

PT and APTT is prolonged
—-APTT is much more sensitive

• anti-Xa assay; MORE PREDICTABLE!

Question 13

What is monitored in a pt who takes warfarin?

Answer 13

• INR

- PT

Question 14

What is the risk of monitoring PT with heparin?

Answer 14

• may lead to OVER-COAGULATION

Question 15

What are the risks of heparin?

Answer 15

• abs to platelets!—-(heparin induced thrombocytopenia)
• BLEEDING
• OSTEOPOROSIS
• s/c injections EVERYDAY

Question 16

What to monitor if the pt has been on unfractionated heparin?

Answer 16

• monitor FBC

- check for the platelet Abs

Question 17

How to reverse heparinn drug action?

Answer 17

• STOP the heparin (STOPS bioavailability of unfractionated heparin)
• –ANTIDote: PROTAMINE SULPHATE (reverses anti-thrombin effect)

Question 18

How effective is PROTAMIN SULPHATE for reversing heparin axn?

Answer 18

• PARTIAL reversal for LMWH

- —complete reversal for unfractionated

Question 19

Name coumarin anit-coagulants.

Answer 19

—INHIBIT vitamin K
warfarin. phenindione. acenocoumarin
phenprocoumon

Question 20

What is affected with warfarin administration?

Answer 20

• PROTEIN C,S (reduces FIRST FEW DAYS)
  2, 7, 9, 10 (3-5DAYS)
  —–no longer have a negative charge (does not form a blood clot)

Question 21

What should be noted when administering warfarin and heparin?

Answer 21

• ALWAYS GIVEN WARFARIN AND HEPARIN TOGETHER (KICK IN HEPARIN IN A WEEK)

Question 22

What is an issue with Warfarin?

Answer 22

• NARROW therapeutic window

- –metabolised in the liver (need to personalise the dose to the individual; some need 1 mg or 15 mg)

Question 23

What is recommended with warfarin administration?

Answer 23

dose to be taken at the SAME time every day

Question 24

What is the INR?

Answer 24

normalizes the PT ratio by adjusting the variability in the sensitivity of the diff. thromboplastins.
—-standardizes reagents

Question 25

What are the MAJOR adverse effects of haemorrhage?

Answer 25

- intensity of t anti-coagulation - concomitant clinical d.o - concomitant use of OTHER meds - BEWARE drug interactions - quality of management

Question 26

What are some bleeding s.es of warfarin?

Answer 26

MILD: bruising/ epistaxis/ haematuria SEVERE: GI/ intracerebral/ sign. DROP in Hb

Question 27

What to do if INR is HIGH?

Answer 27

-DROP 1-2 doses ( 2-3 days of INR to drop) - give VITAMIN K ---if MASSIVE hemorrhage (ADMINISTER clotting factors ) - clinical and lab assessment of response

Question 28

Why is clotting factors reserved for life-threatening conditions?

Answer 28

- $$$ - risk of infection! - in the 50s: Hep.C and HIV

Question 29

How long does it take for vit K and clotting factors to act?

Answer 29

- Vit. K: 6 HRS | - CLOTTING FACTORS: immediate

Question 30

DABIGATRAN

Answer 30

- targets THROMBIN (prevents fibrin clot forming)

Question 31

In whom is dabigatran inhibited?

Answer 31

RENALLY excreted so NOT best for OLDER patients ---risk of v.high INR ----

Question 32

Name Xa inhibitors,

Answer 32

- EDOXABAN - RIVAROXABAN - APIXABAN

Question 33

Why are anti-coagulants given for DVT/ PE and atrial fibrillation?

Answer 33

- don't affect PC AND PS

Question 34

What is warfarin used for?

Answer 34

- those on heart valves and phospholipid diseases | - ---great for preventing arterial events

Question 35

Why are new anti-coagulants preferred nowadays>

Answer 35

- oral - NO monitoring needed - LESS drug interactions

Question 36

What are new anticoagulants used for?

Answer 36

- prophylaxis in hip and knee replacement surgery

Question 37

What do the anti-coagulant drugs target?

Answer 37

- formation of fibrin clot

Question 38

If pt comes in with a suspected stroke, an his ecg shows atrial fibrillation, what medication is he given?

Answer 38

- anti-coagulants (to dissolve the FIBRIN-rich clot) ----not given anti-platelets (unless ecg is -ve and the pt has HIGH BP/ is a smoker/ has DM/ high cholestrol)

Question 39

What does prolonged PT with normal APTT suggest?

Answer 39

Factor VII deficiency

Question 40

WHat does prolonged APTT with NORMAL PT suggest?

Answer 40

Factor VIII, IX, XI, XII | vWF (resp. to transport VIII)