“The anticonvulsant effect of cannabinoid compound has been shown in various models of seizure. On the other hand, there are controversial findings about the role of large conductance calcium-activated potassium (BK) channels in the pathogenesis of epilepsy. Also, there is no data regarding the effect of co-administration of cannabinoid type 1 (CB1) receptor agonists and BK channels antagonists in the acute models of seizure in mice.
In this study, the effect of arachidonyl-2′-chloroethylamide (ACEA), a CB1 receptor agonist, and a BK channel antagonist, paxilline, either alone or in combination was investigated.
Both pentylenetetrazole (PTZ) and maximal electroshock (MES) acute models of seizure were used to evaluate the protective effects of drugs. Mice were randomly selected in different groups: (i) control group; (ii) groups that received different doses of either paxilline or ACEA; and (iii) groups that received combinations of ACEA and paxillin at different doses. In MES model, prevention of hindlimb tonic extension (HLTE) was considered as protective effect. In PTZ model, the required dose of PTZ (mg/kg) to induce tonic-clonic seizure with loss of righting reflex was considered as seizure threshold. In PTZ model, while administration of ACEA per se (5 and 10 mg/kg) caused protective effect against seizure; however, co-administration of ACEA and ineffective doses of paxilline attenuated the antiseizure effects of paxilline. In MES model, while pretreatment by ACEA showed protective effects against seizure; however, co-administration of paxilline and ACEA caused an antagonistic interaction for their antiseizure properties.
Our results showed a protective effect of ACEA in both PTZ and MES acute models of seizure. This effect was attenuated by co-administration with paxilline, suggesting the involvement of BK channels in antiseizure activity of ACEA.”
Design: Multinational double-blinded placebo-controlled trial. Patients randomised in 1:1 ratio to receive cannabidiol or placebo, in addition to stable antiepileptic treatment regime.
Setting: Twenty-three centres in Europe and USA.
Patients: Patients aged 2 years to 18 years with established diagnosis of Dravet syndrome having at least four convulsive seizures during the 28-day baseline period despite regular antiepileptic medication.
Intervention: Adjunctive cannabidiol or placebo oral solution at 20 mg per kilogram of body weight per day.
Primary outcome: Percentage change in median frequency of convulsive seizures per month.
Follow-up period: Outcome measured over a 14-week treatment period in comparison to a 4-week baseline period.
Patient follow-up: One hundred and eight (90%) completed the trial: 85% (52/61) in the cannabidiol group and …”
“Several antiepileptic drugs (AEDs), about 25, are currently clinically available for the treatment of patients with epilepsy. Despite this armamentarium and the many recently introduced AEDs, no major advances have been achieved considering the number of drug resistant patients, while many benefits have been indeed obtained for other clinical outcomes (e.g. better tolerability, less interactions).
Cannabinoids have long been studied for their potential therapeutical use and more recently phytocannabinoids have been considered a valuable tool for the treatment of several neurological disorders including epilepsy.
Among this wide class, the most studied is cannabidiol (CBD) considering its lack of psychotropic effects and its anticonvulsant properties.
Several preclinical studies have tried to understand the mechanism of action of CBD, which still remains largely not understood.
CBD has shown significant anticonvulsant effects mainly in acute animal models of seizures; beneficial effects were reported also in animal models of epileptogenesis and chronic models of epilepsy,
There is indeed sufficient supporting data for clinical development and important antiepileptic effects and the currently ongoing clinical studies will permit the real usefulness of CBD and possibly other cannabinoids.
Undoubtedly, several issues also need to be addressed in the next future (e.g. better pharmacokinetic profiling). Finally, shading light on the mechanism of action and the study of other cannabinoids might represent an advantage for future developments.”
“The pharmacologic and biochemical features of cannabinoids make them candidates for antiseizure medications. At this time, anecdotes have outstripped controlled clinical trials as sources of support for their clinical value.”
“Endocannabinoids are lipid-derived messengers, and both their synthesis and breakdown are under tight spatiotemporal regulation. As retrograde signalling molecules, endocannabinoids are synthesized postsynaptically but activate presynaptic cannabinoid receptor 1 (CB1) receptors to inhibit neurotransmitter release. In turn, CB1-expressing inhibitory and excitatory synapses act as strategically placed control points for activity-dependent regulation of dynamically changing normal and pathological oscillatory network activity. Here, we highlight emerging principles of cannabinoid circuit control and plasticity, and discuss their relevance for epilepsy and related comorbidities. New insights into cannabinoid signalling may facilitate the translation of the recent interest in cannabis-related substances as antiseizure medications to evidence-based treatment strategies.”
“The effects of cannabidiol (CBD) on electrically evoked kindled seizures were studied in conscious, unrestrained rats with chronically implanted cortical and limbic electrodes, and the results were compared with those of delta 9-tetrahydrocannabinol (delta 9-THC), phenytoin (PHT), and ethosuximide (ESM). All drugs were anticonvulsant, but there were marked differences in their effects on afterdischarge (AD) threshold, duration, and amplitude. CBD, like PHT and delta 9-THC, elevated the AD threshold; in contrast, ESM decreased the threshold but suppressed AD spread. CBD, however, also resembled ESM inasmuch as both drugs decreased AD duration and amplitude. Electrophysiologically, the antiseizure effects of CBD were a combination of those of PHT and ESM. The combination of effects may account for the observation that CBD was the most efficacious of the drugs tested against limbic ADs and convulsions. Other properties of CBD were also noted: For example, compared with delta 9-THC, it is a much more selective anticonvulsant vis-à-vis motor toxicity. CBD also lacks the CNS excitatory effects produced by delta 9-THC, PHT, and ESM. These characteristics, combined with its apparently unique set of electrophysiological properties, support the suggestion that CBD has therapeutic potential as an antiepileptic.”
“CBD is the major nonpsychoactive component of Cannabis sativa whose structure was first described by Mechoulam and Shvo (1963); CBD has recently attracted renewed interest for its therapeutic potential in a number of disease states. CBD has been proposed to possess anticonvulsive, neuroprotective, and anti-inflammatory properties in humans.”
“Plant-derived cannabinoids (phytocannabinoids) are compounds with emerging therapeutic potential. Early studies suggested that cannabidiol (CBD) has anticonvulsant properties in animal models and reduced seizure frequency in limited human trials. Here, we examine the antiepileptiform and antiseizure potential of CBD using in vitro electrophysiology and an in vivo animal seizure model…. These findings suggest that CBD acts, potentially in a CB1 receptor-independent manner, to inhibit epileptiform activity in vitro and seizure severity in vivo. Thus, we demonstrate the potential of CBD as a novel antiepileptic drug in the unmet clinical need associated with generalized seizures.”
“In conclusion, our data in separate in vitro models of epileptiform activity and, in particular, the beneficial reductions in seizure severity caused by CBD in an in vivo animal model of generalized seizures suggests that earlier, small-scale clinical trials for CBD in untreated epilepsy warrant urgent renewed investigation.”