Tolerability and Efficacy of a 10:25 Preparation of Δ9-Tetrahydrocannabinol and Cannabidiol for Treatment of Chronic Back or Neck Pain: A Multiple-Dose Escalation Study

INTRODUCTION: The aim was to demonstrate the safety and tolerability of cannabidiol (CBD) with Δ9-THC in patients with moderate to severe chronic back or neck pain unresponsive to over-the-counter non-opioid analgesics. METHODS: This was a non-randomized, single-arm, open-label study. Participants received escalating doses of an oromucosal-administered combination containing 10 mg/mL of Δ9-THC, 25 mg/mL of CBD. On day 1, patients received once-daily 0.5 mL Cybis^® 10:25 (5 mg Δ9-THC plus 12.5 mg CBD daily), escalated at days 8, 15, and 22 to 0.5 mL twice-daily (bd) (10 mg Δ9-THC plus 25 mg CBD daily), 1.0 mL bd (20 mg Δ9-THC plus 50 mg CBD daily), and 1.5 mL bd (30 mg Δ9-THC plus 75 mg CBD daily), respectively. The primary outcome was safety and tolerability, with secondary objectives including pharmacokinetic and efficacy outcomes. RESULTS: 28 patients were enrolled in the study. Their median age was 63.3 years, and half were female. The median history of neck/back pain was 10 years. The pharmacokinetics following single doses of 0.5 mL were variable; however, there were dose-dependent increases in trough levels of CBD and Δ9-THC. Cybis^® 10:25 was well tolerated, with the majority of adverse events of mild severity. The most common adverse events were nausea, vomiting, fatigue, dizziness, headache, paresthesia, and anxiety. There were dose-dependent improvements in numerical pain rating scores (p < 0.001), with clinically significant reductions in pain at 1.0 mL bd and 1.5 mL bd doses (28.8% and 34.1% reductions, respectively, p < 0.001). Depressive symptoms and stress had dose-dependent reductions (p = 0.0182, p < 0.01, respectively). CONCLUSION: In patients with chronic neck/back pain, CBD and Δ9-THC are well tolerated and doses of 1.0 mL bd and 1.5 mL bd showed clinically significant reductions in pain compared to baseline pain scores.