Key result
Cannabis use linked to sudden INR spike to ~7.2 during stable warfarin therapy.
Case Report (n=1)
No
Answers are grounded in this paper and cite their sources.
OBJECTIVE: A 35-year-old Middle Eastern male on warfarin long term with an INR goal of 2.5 (accepted range: 2.0-3.0). The patient has generally been stable on warfarin 10 mg daily from 2010 to 2018, until INR suddenly increased to 7.2 following 1 month of edible cannabis ingestion and cannabis smoking. Patient denied any signs and symptoms of bleeding. No other reasonable causes of the elevation in INR were apparent. The patient was advised to hold 2 doses of warfarin and discontinue cannabis use. The INR dropped below 4 upon discontinuation of cannabis with dose adjustments to warfarin. DISCUSSION: The elevation in INR can be explained by the inhibition of CYP2C9 by cannabis use causing decreased metabolism of warfarin. The interaction between warfarin and cannabis was determined to be probable using the Horn Drug Interaction Probability Scale. CONCLUSIONS: There are no previous reports of interactions between edible cannabis and warfarin, with very few case reports describing the interaction with other forms of cannabis. Close monitoring of INR in patients with concomitant cannabis is recommended for proper warfarin management.
No takes yet. Share an insight, caveat, or question.
Hsu et al. (2019) conducted a case report in Long-term warfarin anticoagulation (n=1). Edible and inhaled cannabis vs. Baseline (stable on warfarin 10 mg daily prior to cannabis use) was evaluated on Increase in INR. Edible and inhaled cannabis use in a patient previously stable on warfarin resulted in a sudden INR increase to 7.2, which resolved upon discontinuation of cannabis.
Synapse has enriched 10 related papers. Consider them for comparative context: