Novel therapies in development for the treatment of traumatic brain injury

In industrialised countries, the mean per capita incidence of traumatic brain injury (TBI) that results in a hospital presentation is 250 per 100,000. In Europe and North America alone, this translates to > 2 million TBI presentations annually. Approximately 25% of these presentations are admitted for hospitalisation. Despite the significance of these figures, there is no single interventional pharmacotherapy that has shown efficacy in the treatment of clinical TBI. This lack of efficacy in clinical trials may be due, in part, to the inherent heterogeneity of the traumatic brain injury population. However, it is the multifactorial nature of secondary injury that also poses a major hurdle, particularly for those therapies that have been designed to specifically target an individual injury factor. It is now becoming increasingly recognised that any successful TBI therapy may have to simultaneously affect multiple injury factors, somewhat analogous to other broad spectrum interventions. Recent efforts in experimental TBI have therefore focussed on developing novel pharmacotherapies that may affect multiple injury factors and thus improve the likelihood of a successful outcome. While a number of interventions are noteworthy in this regard, this review will focus on three novel compounds that show particular promise: magnesium, substance P antagonists and cyclosporin A.