MOA
- Block synthesis of Vit-K dependent clotting factors in the liver
- Vit K is required to syn factors 2, 7, 9, 10
OSA
Depend on the Vit K dependence factors (2, 7, 9, and 10)
- VII: 6 hours
- IX: 24 hours
- X: 40 hours
- II: 60 hours
Indications
- A. Fib
- PE/DVT
- Thromboembolic complication associated with a.fib
=> should not taken w/ ASA or NSAIDS
What is the recommend start dose of warfarin base on ACCP 2012 guideline?
- 10 mg PO QD x 2 days for health adult
- Initiate warfarin on the same day as heparin or LMWH. Overlap anticoag for few days until IRN > 2 for 2 consecutive days => then d/c Heparin or LMWH
Dosage forms of Coumadin
Please Let Greg Brown Brings Peaches To Your Wedding
- 1 mg = Pink
- 2 mg = Lavender
- 2.5 mg = Green
- 3mg = Brown/Tan
- 4 mg = Blue
- 5 mg = Peach
- 6 mg = Teal or Blue- green
- 7.5 mg = Yellow
- 10 mg = White
ADEs
- Hemorrage: gingival bleeding, blood under skin, blood in urine, black stool, nosebleed, cough up blood, vomit blood, hemorrhagic stroke
- GI: N/V/D
- Hemorrhagic skin necrosis
DDI
- Foods:
- Drug incr bleeding
- Drug decr bleeding
Foods:
- Green leafy vegetables: asparagus, cabbage, cauliflower, turnip greens => contain Vit-K = coagulation
Drug incr bleeding
- Glucocorticosteroids
- EtOH
- Salicylates
Drug decr bleeding
- Rifampin, COC, phenytoin, Estrogen => ROPE
Drugs that increase INR
- 3A4 inhibitors: macrolides, protease inhibitors, azole antifungals, grapefruit juice (limit to 3 glasses QD)
- TMP/SMX (Bactrim/Septra), metronidazole (flagyl)
- Garlic, ginger, ginko (genseng decreases INR)
Warfarin & NSAIDs
- Not rec => incr risk of GI bleeding
- NSAID: incr gastric irritation & erosion the protective lining of stomach => cause GI bleed. Also decr cohesive of platelets in clotting formulation
- If need anti-pyretic => use APAP
- If have to use w/ NSAID => monitor INR QW
Warfarin & Bactrim
- Increase risk of bleeding => increase INR
- Avoid if possible, if have to use it, then decr warfarin by 50% while on and after a week d/c of bactrim.
- Monitor INR QW
Warfarin & Quinolone
- Incr effects of warfarin => ACCP rec not use together if possible
- MOA: Reduction of intestinal flora responsible for Vit K production & decr the metabolism & clearance of warfarin
- If use together, monitor INR every other day
Contraindications
- Preg Cat X: Fetal Warfarin Syndrome = chondrodysplasia punctata & CNS abnormalities
- Hypersensitivity
- Easy bleeders like alcoholics
Full anticoag takes how many days
5-10 days
How often we check IRN once it has been stable?
Check 4-12 weeks
- Check 12W in reliable pts w/ stable INRs & no recent change in dose
PK
- Rapidly and completely absorbed
- Protein binding 99%
Reverse INR
- When:
- INR > 10 but no bleeding:
- Serious bleeding, regardless of INR
- INR b/w 4.5-10 w/ high bleeding risk:
- When: INR > 10 or if pt has been bleeding
INR > 10 but no bleeding:
- PO Vit K 2.5-5 mg & hold warfarin
Serious bleeding, regardless of INR
- Slow IV infusion of Vit K 5-10 mg PLUS 4 factor PCC (prothrombin complex concentrate w/ F 2, 7, 9, 10) or give FFP
- 4 Factors: is quicker & preferred
INR b/w 4.5-10 w/ high bleeding risk:
- 1-2.5 mg PO Vit K
Warfarin Pt counseling
- Keep eating habits the same
- Keep a consistent diet of Vit K and E
- Keep appointment for blood testing
- Watch out for interactions with OTC and Rx drugs
- If you forget a dose, take it ASA on the same day. Do not double dose
- Do not take warfarin if you are pregnant or will become
- Watch for any signs of bleeding: dark brown urine, red or tarry black stool, bruising, prolonged bleeding from cuts or gums, nosebleeds, inc menstrual flow.
