It inhibits: Vitamin K epoxide reductase (VKORC1) Activation of Factors II, VII, IX, X Protein C & S (important for early hypercoagulability!) Effect monitored by INR Dosing (very exam & practice relevant) Initial dose: Usually 5 mg once daily Lower initial dose (23 mg) if: Elderly Liver disease Heart failure High bleeding risk Target INR: Most indications (AF, DVT, PE): 2.0 3.0 Mechanical mitral valve: 2.5 3.5 Full anticoagulant effect takes 35 days Types / Form Oral drug Racemic mixture: S-warfarin more potent R-warfarin longer half-life Important clinical pearl Initial hypercoagulable state Because Protein C & S fall first risk of: Warfarin-induced skin necrosis Solution: Bridge with heparin at initiation Antidote & reversal (VERY high-yield) Antidote: Vitamin K (Phytonadione) Situation Management INR high, no bleeding Oral Vitamin K 12.5 mg Serious bleeding IV Vitamin K 510 mg Life-threatening bleeding Vitamin K + PCC (preferred) or FFP PCC = Prothrombin Complex Concentrate (fastest reversal) Side effects Bleeding (most common) Skin necrosis (Protein C deficiency) Purple toe syndrome Teratogenic contraindicated in pregnancy Many drug & food interactions Foods rich in vitamin K (spinach, broccoli) effect Contraindications Pregnancy Active bleeding Severe liver disease Poor compliance (needs frequent INR monitoring) Take-home message Warfarin is: Powerful Cheap Effective But requires knowledge, monitoring, and respect Mastering warfarin = mastering clinical pharmacology & patient safety
Next time, if this happens, you could either scale up your expression tenfold, or you could use the same expression combined with approximately ten times less glutathione resin
Choose the same day each week
Many people with IBS and other digestive issues may find it hard to take probiotics and colon cleanse products because they can be particularly harsh on sensitive stomachs
Gruhn, W
