Anticonvulsive Properties of Cannabidiol in a Model of Generalized Seizure Are Transient Receptor Potential Vanilloid 1 Dependent.

Introduction: Highly purified cannabidiol (CBD) (approved as Epidiolex® in the United States) has demonstrated efficacy with an acceptable safety profile in patients with Lennox-Gastaut or Dravet syndrome in four randomized controlled trials. CBD possesses affinity for many target classes with functional effects relevant to the pathophysiology of many disease types, including epilepsy. Although the mechanism of action of CBD underlying the reduction of seizures in humans is unknown, transient receptor potential vanilloid 1 (TRPV1) represents a plausible target because (1) CBD activates and then desensitizes TRPV1, (2) TRPV1 is overexpressed in models of temporal lobe epilepsy and patients with epilepsy, (3) and TRPV1 modulates neuronal excitability. Methods: To investigate a potential role of TRPV1 in the anticonvulsive effects of CBD, the effect of CBD on seizure threshold was assessed using a mouse maximal electroshock threshold model of generalized seizure in TRPV1 knockout and wildtype mice. The dose dependence of the CBD effect was determined and compared with that of the positive comparator diazepam and vehicle. Results: At 50 and 100 mg/kg, CBD significantly (p<0.0001) increased seizure threshold in wildtype mice compared with TRPV1 knockout and vehicle controls. This effect was observed only at 100 mg/kg in TRPV1 knockout mice compared with knockout vehicle mice, in which gene deletion partially attenuated the CBD-increased seizure threshold. The effect of high-dose CBD in wildtype mice was nevertheless significantly different from vehicle-treated TRPV1 knockout mice (p<0.0001). Bioanalysis confirmed that genotype-specific differential brain exposure to CBD was not responsible for the observed effect on seizure threshold. Conclusion: These data strongly implicate TRPV1 in the potential mechanisms of action for the anticonvulsive effects of CBD. The partial inhibition of the anticonvulsive effect of high-dose CBD in TRPV1 knockout mice may indicate the involvement of targets other than TRPV1. Further characterization of TRPV1 in the anticonvulsive effect of CBD in validated models of seizure is warranted, as is pharmacological investigation of the molecular interaction between CBD and TRPV1.

A Multiple-Dose, Randomized, Double-Blind, Placebo-Controlled, Parallel-Group QT/QTc Study to Evaluate the Electrophysiologic Effects of THC/CBD Spray.

Delta-9-tetrahydrocannabinol (THC)/cannabidiol (CBD) oromucosal spray has proved efficacious in the treatment of spasticity in multiple sclerosis and chronic pain. A thorough QT/QTc study was performed to investigate the effects of THC/CBD spray on electrocardiogram (ECG) parameters in compliance with regulatory requirements, evaluating the effect of a recommended daily dose (8 sprays/day) and supratherapeutic doses (24 or 36 sprays/day) of THC/CBD spray on the QT/QTc interval in 258 healthy volunteers. The safety, tolerability, and pharmacokinetic profile of THC/CBD spray were also evaluated. Therapeutic and supratherapeutic doses of THC/CBD spray had no effect on cardiac repolarization with primary and secondary endpoints of QTcI and QTcF/QTcB, respectively, showing similar results. There was no indication of any effect on heart rate, atrioventricular conduction, or cardiac depolarization and no new clinically relevant morphological changes were observed. Overall, 19 subjects (25.0%) in the supratherapeutic (24/36 daily sprays of THC/CBD spray) dose group and one (1.6%) in the moxifloxacin group withdrew early due to intolerable AEs. Four psychiatric serious adverse events (AEs) in the highest dose group resulted in a reduction in the surpatherapeutic dose to 24 sprays/day. In conclusion, THC/CBD spray does not significantly affect ECG parameters. Additionally, THC/CBD spray is well tolerated at therapeutic doses with an AE profile similar to previous clinical studies.

Non-THC cannabinoids inhibit prostate carcinoma growth in vitro and in vivo: pro-apoptotic effects and underlying mechanisms.

BACKGROUND AND PURPOSE: Cannabinoid receptor activation induces prostate carcinoma cell (PCC) apoptosis, but cannabinoids other than Δ(9) -tetrahydrocannabinol (THC), which lack potency at cannabinoid receptors, have not been investigated. Some of these compounds antagonize transient receptor potential melastatin type-8 (TRPM8) channels, the expression of which is necessary for androgen receptor (AR)-dependent PCC survival. EXPERIMENTAL APPROACH: We tested pure cannabinoids and extracts from Cannabis strains enriched in particular cannabinoids (BDS), on AR-positive (LNCaP and 22RV1) and -negative (DU-145 and PC-3) cells, by evaluating cell viability (MTT test), cell cycle arrest and apoptosis induction, by FACS scans, caspase 3/7 assays, DNA fragmentation and TUNEL, and size of xenograft tumours induced by LNCaP and DU-145 cells. KEY RESULTS: Cannabidiol (CBD) significantly inhibited cell viability. Other compounds became effective in cells deprived of serum for 24 h. Several BDS were more potent than the pure compounds in the presence of serum. CBD-BDS (i.p.) potentiated the effects of bicalutamide and docetaxel against LNCaP and DU-145 xenograft tumours and, given alone, reduced LNCaP xenograft size. CBD (1-10 µM) induced apoptosis and induced markers of intrinsic apoptotic pathways (PUMA and CHOP expression and intracellular Ca(2+)). In LNCaP cells, the pro-apoptotic effect of CBD was only partly due to TRPM8 antagonism and was accompanied by down-regulation of AR, p53 activation and elevation of reactive oxygen species. LNCaP cells differentiated to androgen-insensitive neuroendocrine-like cells were more sensitive to CBD-induced apoptosis. CONCLUSIONS AND IMPLICATIONS: These data support the clinical testing of CBD against prostate carcinoma.

Effects of cannabinoids and cannabinoid-enriched Cannabis extracts on TRP channels and endocannabinoid metabolic enzymes.

BACKGROUND AND PURPOSE: Cannabidiol (CBD) and Δ(9) -tetrahydrocannabinol (THC) interact with transient receptor potential (TRP) channels and enzymes of the endocannabinoid system. EXPERIMENTAL APPROACH: The effects of 11 pure cannabinoids and botanical extracts [botanical drug substance (BDS)] from Cannabis varieties selected to contain a more abundant cannabinoid, on TRPV1, TRPV2, TRPM8, TRPA1, human recombinant diacylglycerol lipase α (DAGLα), rat brain fatty acid amide hydrolase (FAAH), COS cell monoacylglycerol lipase (MAGL), human recombinant N-acylethanolamine acid amide hydrolase (NAAA) and anandamide cellular uptake (ACU) by RBL-2H3 cells, were studied using fluorescence-based calcium assays in transfected cells and radiolabelled substrate-based enzymatic assays. Cannabinol (CBN), cannabichromene (CBC), the acids (CBDA, CBGA, THCA) and propyl homologues (CBDV, CBGV, THCV) of CBD, cannabigerol (CBG) and THC, and tetrahydrocannabivarin acid (THCVA) were also tested. KEY RESULTS: CBD, CBG, CBGV and THCV stimulated and desensitized human TRPV1. CBC, CBD and CBN were potent rat TRPA1 agonists and desensitizers, but THCV-BDS was the most potent compound at this target. CBG-BDS and THCV-BDS were the most potent rat TRPM8 antagonists. All non-acid cannabinoids, except CBC and CBN, potently activated and desensitized rat TRPV2. CBDV and all the acids inhibited DAGLα. Some BDS, but not the pure compounds, inhibited MAGL. CBD was the only compound to inhibit FAAH, whereas the BDS of CBC > CBG > CBGV inhibited NAAA. CBC = CBG > CBD inhibited ACU, as did the BDS of THCVA, CBGV, CBDA and THCA, but the latter extracts were more potent inhibitors. CONCLUSIONS AND IMPLICATIONS: These results are relevant to the analgesic, anti-inflammatory and anti-cancer effects of cannabinoids and Cannabis extracts.