Inhibitory effects of cannabidiol on voltage-dependent sodium currents.

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“Cannabis sativa contains many related compounds known as phytocannabinoids. The main psychoactive and non-psychoactive compounds are Δ9-tetrahydrocannabidiol (THC) and cannabidiol (CBD), respectively.

Much of the evidence for clinical efficacy of CBD-mediated anti-epileptic effects has been from case reports or smaller surveys. The mechanisms for CBD’s anticonvulsant effects are unclear and likely involve non-cannabinoid receptor pathways.

CBD is reported to modulate several ion channels, including sodium channels (Nav). Evaluating therapeutic mechanisms and safety of CBD demands a richer understanding of its interactions with central nervous system targets. Here, we used voltage-clamp electrophysiology of HEK-293 cells and iPSC neurons to characterize the effects of CBD on Nav channels.

Our results show that CBD inhibits hNav1.1-1.7 currents, with an IC50 of 1.9-3.8 μM, suggesting that this inhibition could occur at therapeutically relevant concentrations. A steep Hill slope of ~3 suggested multiple interactions of CBD with Nav channels. CBD exhibited resting-state blockade, became more potent at depolarized potentials, and also slowed recovery from inactivation, supporting the idea that CBD binding preferentially stabilizes inactivated Nav channel states. We also found that CBD inhibits other voltage-dependent currents from diverse channels, including bacterial homomeric Nav channel (NaChBac) and voltage-gated potassium channel subunit Kv2.1. Lastly, the CBD block of Nav was temperature-dependent, with potency increasing at lower temperatures.

We conclude that CBD’s mode of action likely involves (1) compound partitioning in lipid membranes, which alters membrane fluidity affecting gating, and (2) undetermined direct interactions with sodium and potassium channels, whose combined effects are loss of channel excitability.”

https://www.ncbi.nlm.nih.gov/pubmed/30219789

http://www.jbc.org/content/early/2018/09/14/jbc.RA118.004929

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Cannabis for the Treatment of Epilepsy: an Update.

“For millennia, there has been interest in the use of cannabis for the treatment of epilepsy.

However, it is only recently that appropriately powered controlled studies have been completed. In this review, we present an update on the research investigating the use of cannabidiol (CBD), a non-psychoactive component of cannabis, in the treatment of epilepsy.

While the anticonvulsant mechanism of action of CBD has not been entirely elucidated, we discuss the most recent data available including its low affinity for the endocannabinoid receptors and possible indirect modulation of these receptors via blocking the breakdown of anandamide.

Additional targets include activation of the transient receptor potential of vanilloid type-1 (TRPV1), antagonist action at GPR55, targeting of abnormal sodium channels, blocking of T-type calcium channels, modulation of adenosine receptors, modulation of voltage-dependent anion selective channel protein (VDAC1), and modulation of tumor necrosis factor alpha release.

We also discuss the most recent studies on various artisanal CBD products conducted in patients with epilepsy in the USA and internationally. While a high percentage of patients in these studies reported improvement in seizures, these studies were either retrospective or conducted via survey. Dosage/preparation of CBD was either unknown or not controlled in the majority of these studies.

Finally, we present data from both open-label expanded access programs (EAPs) and randomized placebo-controlled trials (RCTs) of a highly purified oral preparation of CBD, which was recently approved by the FDA in the treatment of epilepsy.

In the EAPs, there was a significant improvement in seizure frequency seen in a large number of patients with various types of treatment-refractory epilepsy. The RCTs have shown significant seizure reduction compared to placebo in patients with Dravet syndrome and Lennox-Gastaut syndrome. Finally, we describe the available data on adverse effects and drug-drug interactions with highly purified CBD.

While this product is overall well tolerated, the most common side effects are diarrhea and sedation, with sedation being much more common in patients taking concomitant clobazam. There was also an increased incidence of aspartate aminotransferase and alanine aminotransferase elevations while taking CBD, with many of the patients with these abnormalities also taking concomitant valproate. CBD has a clear interaction with clobazam, significantly increasing the levels of its active metabolite N-desmethylclobazam in several studies; this is felt to be due to CBD’s inhibition of CYP2C19. EAP data demonstrate other possible interactions with rufinamide, zonisamide, topiramate, and eslicarbazepine. Additionally, there is one case report demonstrating need for warfarin dose adjustment with concomitant CBD.

Understanding of CBD’s efficacy and safety in the treatment of TRE has expanded significantly in the last few years. Future controlled studies of various ratios of CBD and THC are needed as there could be further therapeutic potential of these compounds for patients with epilepsy.”

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Anticonvulsant and Neuroprotective Effects of Cannabidiol During the Juvenile Period.

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“Anticonvulsant effects of cannabidiol (CBD), a nonpsychoactive cannabinoid, have not been investigated in the juvenile brain. We hypothesized that CBD would attenuate epileptiform activity at an age when the brain first becomes vulnerable to neurotoxicity and social/cognitive impairments.

To induce seizures, kainic acid (KA) was injected either into the hippocampus (KAih) or systemically (KAip) on postnatal (P) day 20. CBD was coadministered (KA + CBDih, KA + CBDip) or injected 30 minutes postseizure onset (KA/CBDih, KA/CBDip).

Hyperactivity, clonic convulsions, and electroencephalogram rhythmic oscillations were attenuated or absent after KA + CBDih and reduced after KA + CBDip. NeuN immunohistochemistry revealed neuroprotection.

Augmented reactive glia number and expression were reversed in CA1 but persisted deep within the dentate hilus. Parvalbumin-positive (PV+) interneurons were reduced in both models, whereas immunolabeling was dramatically increased within ipsilateral and contralateral dendritic/neuropilar fields following KA + CBDih. Cannabinoid receptor 1 (CB1) expression was minimally affected after KAih contrasting elevations observed after KAip.

Intracranial coadministration data suggest that CBD has higher efficacy in epilepsy with hippocampal focus rather than when extrahippocampal amygdala/cortical structures are triggered by systemic treatments. Inhibition of surviving PV+ and CB1+ interneurons may be facilitated by CBD implying a protective role in regulating hippocampal seizures and neurotoxicity at juvenile ages.”

https://www.ncbi.nlm.nih.gov/pubmed/30169677

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Potential clinical benefits of CBD-rich Cannabis extracts over purified cannabidiol (CBD) in treatment-resistant epilepsy: observational data meta-analysis

“This meta-analysis paper describes the analysis of observational clinical studies on the treatment of refractory epilepsy with cannabidiol (CBD)-based products. Beyond attempting to establish the safety and efficacy of such products, we also investigated if there is enough evidence to assume any difference in efficacy between CBD-rich extracts compared to purified CBD products.

The systematic search took place in February/2017 and updated in December/2017 using the keywords “epilepsy” or “Dravet” or “Lennox-Gastaut” or “CDKL5” combined with “Cannabis”, “cannabinoid”, “cannabidiol” or “CBD” resulting in 199 papers. The qualitative assessment resulted in 11 valid references, with an average impact factor of 8.1 (ranging from 1.4 to 47.8). The categorical data of a total of 670 patients were analyzed by Fischer test. The average daily dose ranged between 1 and 50 mg/kg, with treatment length from 3 to 12 months (mean 6.2 months).

Two thirds of patients reported improvement in the frequency of convulsive crisis (399/622, 64%). There were more reports of improvement from patients treated with CBD-rich extracts (318/447, 71%) than patients treated with purified CBD (81/223, 36%), with statistical significance (p<0.0001).

Nevertheless, when the standard clinical threshold of a “50% reduction or more in the frequency of convulsive crisis” was applied, only 39% of the individuals were considered “responders”, and there was no difference (p=0.56) between treatments with CBD-rich extracts (97/255, 38%) and purified CBD (94/223, 42%).

Patients treated with CBD-rich extracts reported lower average dose (6.1 mg/kg/day) than those using purified CBD (27.1 mg/kg/day). The reports of mild (109/285 vs 291/346, p<0.0001) and severe (23/285 vs 77/346, p<0.0001) adverse effects were more frequent in products containing purified CBD than in CBD-rich extracts.

CBD-rich extracts seem to present a better therapeutic profile than purified CBD, at least in this population of patients with refractory epilepsy. The roots of this difference is likely due to synergistic effects of CBD with other phytocompounds (aka Entourage effect), but this remains to be confirmed in controlled clinical studies.”

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Cannabidiol for Epilepsy: New Hope on the Horizon?

 Clinical Therapeutics Home

“Epilepsy is a common neurologic disorder; it is estimated that ∼50 million people are affected worldwide. About one third of those patients are drug resistant, defined as failure to stop all seizures despite adequate trials of at least 2 appropriate medications. There has been an enormous interest in developing antiepileptic drugs with novel mechanisms of action. This review discusses the evidence supporting the anticonvulsant properties of cannabis in humans, focusing on cannabidiol. We begin by exploring the early and somewhat anecdotal evidence that was recently replaced by high-quality data from randomized controlled studies, which subsequently led to the US Food and Drug Administration approval of a purified cannabidiol extract for the treatment of 2 highly refractory pediatric epilepsy syndromes (Dravet and Lennox-Gastaut).”

https://www.ncbi.nlm.nih.gov/pubmed/30150078

https://www.clinicaltherapeutics.com/article/S0149-2918(18)30325-4/fulltext

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Efficacy and Safety of Adjunctive Cannabidiol in Patients with Lennox-Gastaut Syndrome: A Systematic Review and Meta-Analysis.

“Lennox-Gastaut syndrome (LGS) is a severe developmental epileptic encephalopathy, and available interventions fail to control seizures in most patients. Cannabidiol (CBD) is a major chemical of marijuana, which has anti-seizure properties and different mechanisms of action compared with other approved antiepileptic drugs (AEDs).

OBJECTIVE:

The aim was to evaluate the efficacy and safety of CBD as adjunctive treatment for seizures in patients with LGS using meta-analytical techniques.

METHODS:

Randomized, placebo-controlled, single- or double-blinded trials were identified. Main outcomes included the ≥ 50% reduction in baseline drop and non-drop seizure frequency, and the incidence of treatment withdrawal and adverse events (AEs). Risk ratios (RRs) with 95% confidence intervals (CIs) were estimated through the inverse variance method.

RESULTS:

Two trials were included involving 396 participants. Patients presenting ≥ 50% reduction in drop seizure frequency during the treatment were 40.0% with CBD and 19.3% with placebo [RR 2.12 (95% CI 1.48-3.03); p < 0.001]. The rate of non-drop seizure frequency was reduced by 50% or more in 49.4% of patients in the CBD and 30.4% in the placebo arms [RR 1.62 (95% CI 1.09-2.43); p = 0.018]. The RR for CBD withdrawal was 4.93 (95% CI 1.50-16.22; p = 0.009). The RR to develop any AE during CBD treatment was 1.24 (95% CI 1.11-1.38; p < 0.001). AEs significantly associated with CBD were somnolence, decreased appetite, diarrhea and increased serum aminotransferases.

CONCLUSIONS:

Adjunctive CBD resulted in a greater reduction in seizure frequency and a higher rate of AEs than placebo in patients with LGS presenting seizures uncontrolled by concomitant AEDs.”

“Cannabidiol in the Lennox-Gastaut Syndrome.”  https://www.nejm.org/doi/10.1056/NEJMc1807878

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Cannabidiol improves frequency and severity of seizures and reduces adverse events in an open-label add-on prospective study.

“The objective of this study was to characterize the changes in adverse events, seizure severity, and frequency in response to a pharmaceutical formulation of highly purified cannabidiol (CBD; Epidiolex®) in a large, prospective, single-center, open-label study. We initiated CBD in 72 children and 60 adults with treatment-resistant epilepsy (TRE) at 5 mg/kg/day and titrated it up to a maximum dosage of 50 mg/kg/day. At each visit, we monitored treatment adverse events with the adverse events profile (AEP), seizure severity using the Chalfont Seizure Severity Scale (CSSS), and seizure frequency (SF) using seizure calendars. We analyzed data for the enrollment and visits at 12, 24, and 48 weeks. We recorded AEP, CSSS, and SF at each follow-up visit for the weeks preceding the visit (seizures were averaged over 2-week periods). Of the 139 study participants in this ongoing study, at the time of analysis, 132 had 12-week, 88 had 24-week, and 61 had 48-week data. Study retention was 77% at one year. There were no significant differences between participants who contributed all 4 data points and those who contributed 2 or 3 data points in baseline demographic and AEP/SF/CSSS measures. For all participants, AEP decreased between CBD initiation and the 12-week visit (40.8 vs. 33.2; p < 0.0001) with stable AEP scores thereafter (all p ≥ 0.14). Chalfont Seizure Severity Scale scores were 80.7 at baseline, decreasing to 39.2 at 12 weeks (p < 0.0001) and stable CSSS thereafter (all p ≥ 0.19). Bi-weekly SF decreased from a mean of 144.4 at entry to 52.2 at 12 weeks (p = 0.01) and remained stable thereafter (all p ≥ 0.65). Analyses of the pediatric and adult subgroups revealed similar patterns. Most patients were treated with dosages of CBD between 20 and 30 mg/kg/day. For the first time, this prospective, open-label safety study of CBD in TRE provides evidence for significant improvements in AEP, CSSS, and SF at 12 weeks that are sustained over the 48-week duration of treatment.”

https://www.ncbi.nlm.nih.gov/pubmed/30100226

https://www.epilepsybehavior.com/article/S1525-5050(18)30473-6/fulltext

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Open-label use of Highly* purified CBD (Epidiolex®) in patients with CDKL5 deficiency disorder and Aicardi, Dup15q, and Doose syndromes.

“We studied our collective open-label, compassionate use experience in using cannabidiol (CBD) to treat epilepsy in patients with CDKL5 deficiency disorder and Aicardi, Doose, and Dup15q syndromes. This open-label drug trial provides class III evidence for the long-term safety and efficacy of cannabidiol (CBD) administration in patients with treatment-resistant epilepsy (TRE) associated with CDKL5 deficiency disorder and Aicardi, Dup15q, and Doose syndromes. Adjuvant therapy with CBD showed similar safety and efficacy for these four syndromes as reported in a diverse population of TRE etiologies.” https://www.ncbi.nlm.nih.gov/pubmed/30006259 https://www.epilepsybehavior.com/article/S1525-5050(18)30191-4/fulltext

“Medical cannabis for epilepsy approved in FDA first”  https://www.medicalnewstoday.com/articles/322283.php

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Investigational cannabinoids in seizure disorders, what have we learned thus far?

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“The anticonvulsant activity of cannabinoids attracted much attention in the last decade. Cannabinoids that are currently investigated with the intention of making them drugs for the treatment of epilepsy are cannabidiol, cannabidivarin, Δ9-tetrahydrocannabivarin and Δ9-tetrahydrocannabinolic acid.

Areas covered. In this review, the authors look at the results of pre-clinical and clinical studies with investigational cannabinoids. Relevant literature was searched for in MEDLINE, SCOPUS, EBSCO, GOOGLE SCHOLAR and SCINDEX databases.

Expert opinion. Pre-clinical studies confirmed anticonvulsant activity of cannabidiol and cannabidivarin in a variety of epilepsy models. While the results of clinical trials with cannabidivarin are still awaited, cannabidiol showed clear therapeutic benefit and good safety in patients with therapy resistant seizures associated with Dravet syndrome and in patients with Lennox-Gastaut syndrome who have drop seizures. However, the full therapeutic potential of cannabinoids in treatment-resistant epilepsy needs to be investigated in the near future.”

https://www.ncbi.nlm.nih.gov/pubmed/29842819

https://www.tandfonline.com/doi/abs/10.1080/13543784.2018.1482275

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Endocannabinoid CB1 receptors are involved in antiepileptogenic effect of low frequency electrical stimulation during perforant path kindling in rats.

Epilepsy Research

“Administration of low-frequency electrical stimulation (LFS) at the kindling site has an antiepileptogenic effect. In the present study, we investigated the role of cannabinoid receptors type 1 (CB1) in mediating the inhibitory effects of LFS on the development of perforant path kindled seizures.

RESULTS:

Application of LFS had inhibitory effect on development of kindled seizures (kindling rate). Microinjection of AM281 (0.5 μg/μl) immediately after the last kindling stimulation (before LFS application) reduced the inhibitory effect of LFS on the kindling rate and suppressed the effects of LFS on potentiation (increasing the magnitude) of both population spike amplitude and population excitatory postsynaptic potential slope during kindling acquisition. AM281 pretreatment also prevented the effects of LFS on kindling-induced increase in early and late paired pulse depression. The higher dose of AM281 (2 μg/μl) failed to exert the effects observed with its lower dose (0.5 μg/μl). In addition, there was a decreased CB1 receptors immunostaining in kindled animals compared to control. However, application of LFS following kindling stimulations led to overexpression of CB1 receptors in the dentate gyrus.

CONCLUSION:

Obtained results showed that activation of overexpressed cannabinoid CB1 receptors by endogenous cannabinoids may have a role in mediating the inhibitory effect of LFS on perforant path kindled seizures.”

https://www.ncbi.nlm.nih.gov/pubmed/29800824

https://www.sciencedirect.com/science/article/pii/S0920121117304291?via%3Dihub

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