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
Its often needed for those with gallstones or cholecystitis
Ensure full contact with no lifted edges
Can my compounding pharmacist check this interaction for me
confirm current information before ordering
Although less than 1% of gut microbiota possess the genes required for TMA synthesis, these relevant microbial communities are still sufficient to drive significant TMA production
