Marijuana interaction with warfarin reported
Researchers from the Cheyenne Veterans Affairs Medical Center, in Wyoming report that when taken together, 1 patient experienced bleeding from the blood “thinner” warfarin (Coumadin).
First, the details.
- A 56-year-old man had been treated with warfarin for 11 years after heart valve replacement.
- He came to the hospital with upper gastrointestinal bleeding.
- His INR value was very high at 10.41, and his hemoglobin level was low at 6.6 g/dL.
- The INR test measures the ability of blood clot: normal is 0.8 to 1.2.
- A normal hemoglobin count is 14-17 g/dL for men.
- He was treated to control his blood loss and left the hospital after 7 days.
- 15 days later he returned with a constant nosebleed and increased bruising.
- His INR value was even higher at 11.55.
- Again, he was treated.
- It was learned that the patient smoked marijuana more frequently throughout the period of these 2 hospitalizations due to depression.
- He was counseled about the potential interaction of warfarin and marijuana.
- He stopped smoking pot, and during the next 9 months his INR values ranged from 1.08 to 4.40 with no significant bleeding complications.
The bottom line?
This is the first reported case of a warfarin-marijuana interaction. More clinical reports would be useful to confirm this interaction.
A PubMed search since this research was published revealed nothing new on this topic.
6/17/09 19:08 JR; 2/3/11 21:52 JR
