Efficacy and safety of dexanabinol in severe traumatic brain injury : results of a phase III randomised, placebo-controlled, clinical trial

Background Traumatic brain injury is a major cause of death and disability. We sought to assess the safety and efficacy of dexanabinol, a synthetic cannabinoid analogue devoid of psychotropic activity, in severe traumatic brain injury. Methods 861 patients with severe traumatic brain injury admitted to 86 specialist centres from 15 countries were included in a multi-centre, placebo-controlled, phase III trial. Patients were randomised to receive a single intravenous 150 mg dose of dexanabinol or placebo within 6 h of injury. The primary outcome was the extended Glasgow outcome scale assessed at 6 months, with the point of dichotomisation into unfavourable versus favourable outcome differentiated by baseline prognostic risk. Prespecified subgroup analyses were defined by injury severity, recruitment rate, and time to dosing. Secondary analysis included control of intracranial pressure and quality of life. Analysis were prespecified in the protocol and the statistical analysis plan. This study is registered with ClinicalTrials.gov, number NCT00129857. Findings 846 patients were included in the efficacy analysis. The extended Glasgow outcome scale at 6 months did not differ between groups; 215 (50%) patients in the dexanabinol group and 214 (51%) patients in the placebo group had an unfavourable outcome (odds ratio for a favourable response 1.04; 95% CI 0.79-1.36). Improvements in the control of intracranial pressure or quality of life were not recorded and subgroup analysis showed no indication of differential treatment effects. Dexanabinol was not associated with hepatic, renal, or cardiac toxic effects. Interpretation Dexanabinol is safe, but is not efficacious in the treatment of traumatic brain injury.