Warfarin inhibits VKOR. Hence it disrupts vitamin K dependent $\gamma$-carboxylation of Fc- II, VII, IX, X.
But what exactly it does to Protein C and Protein S? How does it also affect anticoagulant system?
[Ref. Kim, Yesel, and Oh Young Bang. “Paradoxical Procoagulant Effect of Early Doses of Warfarin: Possible Role of Non-Vitamin K Oral Anticoagulant in Patients with Atrial Fibrillation-Related Stroke.” Journal of stroke vol. 17,2 (2015): 216-8. doi:10.5853/jos.2015.17.2.216
I couldn't find an article regarding the mechanism of this inhibition. Any help will be appreciated.