Drug Interactions in People on Cannabidiol: Is There Cause for Concern?

Introduction: Cannabidiol (CBD) exhibits multiple therapeutic properties, but its use in advanced cancer patients raises concerns about potential drug-drug interactions (DDIs) due to polypharmacy. This study aims to look for evidence of DDIs between concomitant medications and CBD oil in a randomized placebo-controlled trial of CBD oil for symptom control (MedCan-1 parent study). Materials and Methods: Surrogate measures were used to identify possible drug interactions: (1) the maximum mL of oil self-selected by patients in CBD or placebo groups in relation to opioids, specific drug groups, or individual agents; (2) the occurrence of any new or worse adverse effect in relation to the study arm and the concomitant medication classes/medications of interest. Results: The dose of CBD self-selected by participants was not related to opioid use or medications, including benzodiazepines and antipsychotics. The likelihood of developing an adverse effect while on study or when taking specific medications was not increased by CBD. Participants on paracetamol tolerated a higher dose of CBD. Discussion: Concerns regarding the development of clinically significant drug interactions when taking CBD in the context of anti-cancer and other concomitant medications at least in the short term may be unfounded.