Discussion
Elevated warfarin levels post-injury can increase cerebral hemorrhage risk, possibly worsening TBI. TBI might also elevate warfarin levels, heightening its anticoagulant effects. Therefore, assessing injury severity levels and PT-INR values in patients with TBI on warfarin is crucial to anticipate delayed bleeding risks.
Methods
We induced TBI in mice after pre-treatment with warfarin and analyzed TBI exacerbation based on the prothrombin time-international normalized ratio (PT-INR) value, brain hemorrhage volume, blood warfarin and 7-hydroxywarfarin levels, and cytochrome P450 2C9 (CYP2C9) protein expression. C57BL/6J mice fed with a vitamin K-deficient diet received oral warfarin (low dose, 0.35 mg/kg/24 h; high dose, 0.70 mg/kg/24 h), and focal brain damage was induced in the cerebral cortices using a brain contusion device. Warfarin-treated injured mice were compared with sham-treated mice (scalp incision alone or scalp incision + bone window formation).
Results
When warfarin was administered, the PT-INR value and brain hemorrhage volume associated with cerebral contusion increased on the first day post-injury. High blood warfarin and 7-hydroxywarfarin levels were observed. However, no significant differences in CYP2C9 expression were observed between the groups.