Sean asked
Can you use tramadol and warfarin together?
Answer
There is a potential major interaction between tramadol and warfarin. While the exact mechanism behind the interaction is not known, co-administration of tramadol and warfarin has led to increased INR levels in some cases.
The chances of significant bleeding in those taking tramadol and warfarin doesn't appear to be high, but caution is nonetheless advised.
Warfarin - Tramadol Interaction
Warfarin
Warfarin is an oral anticoagulant that inhibits the synthesis of vitamin K-dependent coagulation factors II, VII, IX, and X. While effective, warfarin generally takes prudent dosage adjustment to attain a safe and effective dose. Taking medication that interacts with warfarin or thins the blood can put individuals at risk for serious bleeding events.
Tramadol
Tramadol has a unique mechanism of action. It is opioid agonist similar to hydrocodone and oxycodone although is considered less potent. In addition to its opioid effects, it also works as both a serotonin and norepinephrine re-uptake inhibitor.
Tramadol is thought to interact with warfarin and decrease blood coagulation via several mechanisms:
- Tramadol can increase serotonin levels in the body. Increased serotonin levels can have thinning effects on the blood. This can potentially cause bleeding events in those taking anticoagulant drugs such as warfarin.
- Tramadol may inhibit the metabolizing enzyme CYP 2D6 in some individuals. CYP 2D6 is one of the major enzymes involved in warfarin metabolism. Inhibition of this enzyme could potentially increase warfarin levels, leading to an increase in INR which could potentially increase the risk of bleeding events.
Case Studies
Several studies have reported on specific cases in which tramadol was thought to have led to bleeding events in those taking warfarin. One case study reported the following:
"a 65-year-old man in previously stable condition who was being treated at our anticoagulation clinic. Within 6 days of starting tramadol 50 mg twice/day, the patient's INR rose from 2.5 to 6.14...A 30% dosage reduction from warfarin 60 to 42 mg/week was eventually needed."
In the above case study, a decrease in the patients warfarin dose was needed due to either the anticoagulant effect of tramadol or metabolism inhibition as described above.
Recommendation
If tramadol and warfarin are used together, it is recommended to closely monitor individuals on the combination for changes in INR and symptoms of bleeding such as:
- Easy bruising
- Blood in the stool
- Bleeding gums
In some situations, a pain relieving medication other than tramadol may be warranted for those taking warfarin.
