A 65-year-old male with a history of atrial fibrillation is…
A 65-year-old male with a history of atrial fibrillation is being treated with Warfarin. He reports using marijuana and ibuprofen to assist in his osteoarthritic pain. During a routine follow-up visit, his INR was found to be 4.0. Which of the following is the most likely cause of his elevated INR level?