Facilitation of spinal GABAergic inhibition with benzodiazepines (BZDs) reverses pain sensitization in animals; however, the use of BZDs in man is limited by their sedative effect. The antihyperalgesic effects of GABA A agonists are mediated by GABA A receptors containing a2 subunits, whereas sedation is linked to a1 subunit-containing receptors. a2 and a3 selective GABA A receptor modulators have been tested in animals but are not yet available for use in human beings. Clobazam is a 1,5-BZD, which exhibits less cognitive side effects than other benzodiazepines. Here, we studied its antihyperalgesic effects in a mouse model of neuropathic pain. Clobazam showed a dose-dependent antihyperalgesic effect in the chronic constriction injury (CCI) model of neuropathic pain, peaking at 1 hr after administration and lasting for 4 hr with no relevant sedation at a dose of 3 mg/kg. At higher doses, the antihyperalgesic effect was stronger, but sedation became significant. The blood and brain kinetics of clobazam were linear over the range of doses tested with a short half-life of the parent compound and a ready penetration of the blood-brain barrier. Clobazam blood concentrations decreased rapidly, falling below the limit of detection at 120 min. after drug application. Its main metabolite, N-desmethyl-clobazam, showed more delayed and prolonged pharmacokinetics, partly explaining why antihyperalgesia persisted when clobazam was no longer detectable in the blood. Considering its therapeutic margin and its pharmacokinetic properties, clobazam would be a valuable compound to assess the role of the GABAergic pathway in pain transmission in human beings.Diminished synaptic inhibition in the spinal cord critically contributes to central sensitization, a key phenomenon in chronic inflammatory and neuropathic pain. The role of glycinergic and c-aminobutyric acid (GABA)ergic neurons in this process has been widely described [1,2]. Therefore, facilitation of the spinal GABAergic input is a rational approach to compensate for diminished inhibitory pain control. In fact, the antihyperalgesic effect of several GABA A agonists such as muscimol or of positive allosteric modulators such as diazepam has been demonstrated in animals [3].In human beings, research on the analgesic effect of BZDs is scarce and controversial. In clinical research, diazepam has been used as an active placebo in a study seeking to demonstrate the analgesic effect of fentanyl in patients with chronic non-cancer neuropathic pain [4]. On the other hand, clonazepam is widely used in practice to treat neuropathic pain and has demonstrated efficacy in myofascial pain, temporomandibular joint dysfunction, cancer-related neuropathic pain and in stomatodynia when used topically [5][6][7][8]. However, the use of BZDs in chronic pain is rather limited by their side effects, such as sedation, memory impairment and dependence.Advances in the understanding of the molecular diversity of GABA A receptors have suggested that the therapeutic index might become improved ...