I. Mechanism: The formation of prothrombin II, VII, IX and X requires the formation of hydroquinone with the participation of Vitk1. But Warfarin inhibits Vitk1 hydroquinone formation. Therefore, Warfarin has no effect on the above-mentioned prothrombinogen formation. It takes 4-5 half-lives for Warfarin to take effect after application, i.e. when they are exhausted. Usage: Warfarin can be started with heparin (WMI), and then discontinued after Warfarin has worked. Dose adjustment target: PT > 50%, INR 2.3 individual differences, so the adjustment time is about 2 weeks, so not used as a postoperative thrombotic disease prevention. It also requires 4-5 half-lives to recover function after discontinuation. Start with 5-20mg qd; check PT daily until therapeutic levels are reached. Dose is usually adjusted after 4-6 days. Warfarin has an onset of action at 12 hours, with a peak at 36 hours. INR is tested at this time Biw x 4 times; then qw x 4 times; and then 4-6w once. Generally taken orally as 1 or 1/2 tablets. If the weekly dose is less than one tablet, it is better to take it without splitting or 1/2 tablet for two days. No need to take 1/4 tablet. Increase or decrease the dose to 1 tablet/week is appropriate. III. Influencing factors 1. Synergistic effect: quinolone and macrolide, amoxicillin ① can produce VIK and coagulation of seedlings ② replace the warfarin with Alb binding site on down. ③Inhibit cytochrome P450-mediated metabolic reactions and decrease the elimination rate of warfarin. ②Tramadol ③Fish oil ④Genetic variation 2. Diminishing effect Cisplatin Ribavirin IV. Complications: ① Bleeding (10% per year) ②Fracture sparing ③Soft tissue necrosis (atrial, skin), less.