Prescription cannabidiol for seizure disorder management: Initial drug-drug interaction management by specialty pharmacists.

Purpose: To describe the presence, type, and management of drug-drug interactions (DDIs) at prescription cannabidiol (CBD) therapy initiation.

Methods: We conducted a single-center, retrospective study of patients prescribed CBD from a medical center's neurology clinic for seizure management from January 2019 through April 2020. Patients were excluded if they were enrolled in a CBD clinical trial or the insurance approval or medication fulfillment process was not completed by the center's specialty pharmacy. The primary outcomes were the numbers, types, and management of DDIs identified at the time of CBD prescribing.

Results: Of the 136 patients included, 109 (80%) had a DDI identified at baseline. Of the 260 DDIs, 71% (n = 184) were pharmacodynamic and 29% (n = 76) were pharmacokinetic in nature. Management of the 260 DDIs detected included counseling only (89% [n = 232 interactions]), discontinuation of the interacting agent [9% (n = 22 interactions]), and dosage change for the interacting agent [2% (n = 6 interactions]). Clobazam was the most commonly identified interacting medication (n = 63, 24%), while valproic acid accounted for 10% (n = 26) of the DDIs. The population was predominantly white (n = 115, 85%), 18 years of age or younger (n = 92, 68%), and had an indication for prescription CBD treatment of Lennox-Gastaut syndrome (n = 117, 86%).

Conclusion: This study provides new information on the role that integrated specialty pharmacists can play in identifying and managing initial DDIs in patients starting prescription CBD.