2. is an anticoagulant normally used in the prevention
of thrombosis , thromboembolism and the formation of
blood clots in the blood vessels and their migration
elsewhere in the body. It was referred to as a "blood
thinner", this is a misnomer, since it does not affect
the viscosity of blood
.
Warfarin
3. Mechanism of action
Warfarin inhibits the vitamin K-dependent
synthesis of biologically active forms of the
calcium dependent clotting factors II , VII, IX
and X, as well as the regulatory factors protein
C, protein S
.
4. Indications of wafarin
• Deep-vein thrombosis.
• Pulmonary embolism
• Atrial fibrillation which is risk
of embolisation.
• Mechanical prosthetic heart
valves (to prevent emboli
developing on the valves).
5. *It is essential that the INR be determined daily or on alternate
days in early days of treatment, then at longer intervals
(depending on response) then up to every 12 weeks.
Monitoring
*
Baseline INR is recommended prior to initiating warfarin
therapy to assess sensitivity
.
*
An INR within the last 48 hours is acceptable as a current
baseline INR
.
*
With initial dosing, the INR will usually increase within 24-
36 hours
.
6. Monitoring of INR
INR
3.5
INR
2-3
*
Recurrent DVT
*
Recurrent pulmonary
embolism
.
(
3
* )
Mechanical MV
*
DVT
*
Pulmonary embolism
*Atrial fibrillation
*
DCM
*Mural thrombus
*
before & after
Cardioversion
.
*
mechanical AV (3)
*
Post MI (2.5)
*
Antiphospholipid syndrome
8. Presentations of warfarin toxicity
Major bleeding e.g. : * : 1)
hemorrhage
*
GI hemorrhage
*
intracranial bleeding
*
retroperitoneal bleeding
*Minor bleeding e.g. :
* mucous membranes
* subconjunctival hemorrhage
* hematuria
*epistaxis, and ecchymoses
9. Follow))Presentations of warfarin toxicity
2
)
Skin necrosis: usually observed between the third and eighth
days of therapy, is a relatively uncommon
.
It may require treatment through debridement or amputation of
the affected tissue
.
It occurs more frequently in women and in patients with
preexisting protein C deficiency
.
10. Follow))Presentations of warfarin toxicity
:
3
)
Osteoporosis
The mechanism was thought to be a combination of reduced
intake of vitamin K, which is necessary for bone health, and
inhibition by warfarin of vitamin K-mediated carboxylation of
certain bone proteins, rendering them nonfunctional
.
11. Follow))Presentations of warfarin toxicity
4
)
Purple toe syndrome
:
It is another rare complication that may occur early during
warfarin treatment (usually within 3 to 8 weeks of
commencement). This condition is thought to result from
small deposits of cholesterol breaking loose and flowing
into the blood vessels in the skin of the feet, which causes
a bluish purple color and may be painful
.
It is typically thought to affect the big toe, but it affects other
parts of the feet as well, including the bottom of the foot
(plantar surface). The occurrence of purple toe syndrome
may require discontinuation of warfarin
.
13. Natural Products That Can Alter the
Anticoagulant Effect of Warfarin
Decreased Anticoagulant
Effect
Increased Anticoagulant
Effect
Alfalfa Asafetida , Clove Oil
Ginseng Garlic ,Ginger
Ginseng ,Anise
14. INR reversal protocol
Overdose of warfarin
INR <5
No
significant
bleeding
INR 5-9
No
significant
bleeding
*
Hold the
dose of
warfarin
*
Resume
warfarin at
lower dose
when INR
therapeutic
INR >9
With or
without
bleeding
*
D/C
warfarin
*
FFP
15ml/kg
+/- use of
profilnine
SD 25-50
U/kg r
FVIIa
40µg/kg
*
resume
warfarin
at lower
dose
when
INR
therapeut
ic
Serious
bleeding at
any INR
D/C
warfarin
.
*
*
FFP
15ml/kg
+/- use of
profilnine
SD 25-50
U/kg r
FVIIa
40µg/kg