A cannabinoid derivative, dexanabinol (HU-211), could be the first neuroprotective agent to be approved for human use. If it is successful it might become a "standard inclusion in the kit bag of every medic and ambulance", says neurosurgeon Nachshon Knoller (Tel Hashomer,Israel).

Dexanabinol is a non-psychotropic derivative of a synthetic family of tetrahydrocannabinoid analogues. The drug has three independent mechanisms of action: it blocks glutamate-induced neurotoxicity; it scavenges both peroxy and hydroxy free-radicals; and it inhibits the action of the inflammatory cytokine alpha-tumour necrosis factor. "The triple action stops the spread of the primary neuronal damage from the core of injury to the surrounding brain tissue, even after a single intravenous injection, up to 6 hours after the initial insult", says Raphael Mechoulam, professor of pharmacology, Hadassah Medical School, Jerusalem, Israel.

The results of a UK phase I clinical trial showing lack of adverse reactions to dexanabinol and results from earlier animal studies were presented on Nov 15 in Washington, DC, USA, at the annual meeting of the Society of Neurotrauma. A phase II clinical study of dexanabinol started in Israel on Nov 9, under the auspices of the American Brain Injury Consortium, in patients with severe head injury exhibiting abnormal computed tomography scans and requiring intracranial pressure monitoring.