Cannabinoids in the Treatment of Epilepsy: Current Status and Future Prospects.

Cannabidiol (CBD) is one of the prominent phytocannabinoids found in Cannabis sativa, differentiating from Δ9-tetrahydrocannabinol (THC) for its non-intoxicating profile and its antianxiety/antipsychotic effects. CBD is a multi-target drug whose anti-convulsant properties are supposed to be independent of endocannabinoid receptor CB1 and might be related to several underlying mechanisms, such as antagonism on the orphan GPR55 receptor, regulation of adenosine tone, activation of 5HT1A receptors and modulation of calcium intracellular levels. CBD is a lipophilic compound with low oral bioavailability (6%) due to poor intestinal absorption and high first-pass metabolism. Its exposure parameters are greatly influenced by feeding status (ie, high fat-containing meals). It is mainly metabolized by cytochrome P 450 (CYP) 3A4 and 2C19, which it strongly inhibits. A proprietary formulation of highly purified, plant-derived CBD has been recently licensed as an adjunctive treatment for Dravet syndrome (DS) and Lennox-Gastaut syndrome (LGS), while it is being currently investigated in tuberous sclerosis complex. The regulatory agencies' approval was granted based on four pivotal double-blind, placebo-controlled, randomized clinical trials (RCTs) on overall 154 DS patients and 396 LGS ones, receiving CBD 10 or 20 mg/kg/day BID as active treatment. The primary endpoint (reduction in monthly seizure frequency) was met by both CBD doses. Most patients reported adverse events (AEs), generally from mild to moderate and transient, which mainly consisted of somnolence, sedation, decreased appetite, diarrhea and elevation in aminotransferase levels, the last being documented only in subjects on concomitant valproate therapy. The interaction between CBD and clobazam, likely due to CYP2C19 inhibition, might contribute to some AEs, especially somnolence, but also to CBD clinical effectiveness. Cannabidivarin (CBDV), the propyl analogue of CBD, showed anti-convulsant properties in pre-clinical studies, but a plant-derived, purified proprietary formulation of CBDV recently failed the Phase II RCT in patients with uncontrolled focal seizures.

Neuromuscular magnetic stimulation counteracts muscle decline in ALS patients: results of a randomized, double-blind, controlled study.

The aim of the study was to verify whether neuromuscular magnetic stimulation (NMMS) improves muscle function in spinal-onset amyotrophic lateral sclerosis (ALS) patients. Twenty-two ALS patients were randomized in two groups to receive, daily for two weeks, NMMS in right or left arm (referred to as real-NMMS, rNMMS), and sham NMMS (sNMMS) in the opposite arm. All the patients underwent a median nerve conduction (compound muscle action potential, CMAP) study and a clinical examination that included a handgrip strength test and an evaluation of upper limb muscle strength by means of the Medical Research Council Muscle Scale (MRC). Muscle biopsy was then performed bilaterally on the flexor carpi radialis muscle to monitor morpho-functional parameters and molecular changes. Patients and physicians who performed examinations were blinded to the side of real intervention. The primary outcome was the change in the muscle strength in upper arms. The secondary outcomes were the change from baseline in the CMAP amplitudes, in the nicotinic ACh currents, in the expression levels of a selected panel of genes involved in muscle growth and atrophy, and in histomorphometric parameters of ALS muscle fibers. The Repeated Measures (RM) ANOVA with a Greenhouse-Geisser correction (sphericity not assumed) showed a significant effect [F(3, 63) = 5.907, p < 0.01] of rNMMS on MRC scale at the flexor carpi radialis muscle, thus demonstrating that the rNMMS significantly improves muscle strength in flexor muscles in the forearm. Secondary outcomes showed that the improvement observed in rNMMS-treated muscles was associated to counteracting muscle atrophy, down-modulating the proteolysis, and increasing the efficacy of nicotinic ACh receptors (AChRs). We did not observe any significant difference in pre- and post-stimulation CMAP amplitudes, evoked by median nerve stimulation. This suggests that the improvement in muscle strength observed in the stimulated arm is unlikely related to reinnervation. The real and sham treatments were well tolerated without evident side effects. Although promising, this is a proof of concept study, without an immediate clinical translation, that requires further clinical validation.

Modulation of GABAA Receptors in the Treatment of Epilepsy.

BACKGROUND: A variety of evidence suggested that an imbalance in excitatory and inhibitory neurotransmission could be one of the pathophysiological mechanisms underlying the occurrence and progression of seizures. Understanding the causes of this imbalance may provide essential insight into the basic mechanisms of epilepsy and may uncover novel targets for future drug therapies. Accordingly, GABA is the most important inhibitory neurotransmitter in the CNS and its receptors (e.g., GABAARs) can still be relevant targets of new antiepileptic drugs (AEDs). METHODS: Up to now, a variety of modulating agents that directly or indirectly act at GABAARs have been proposed for restoring the physiological balance of excitation and inhibition in the epileptogenic brain. While benzodiazepine, barbiturates and allosteric modulators of GABAARs are well-known for their anticonvulsant effect, new compounds as modulators of chloride homeostasis or phytocannabinoids are not completely unraveled and their antiepileptic action is still matter of debate. In addition, several inflammatory mediators as cytokines and chemokines play an important role in the modulation of GABAAR function, even if further research is needed to translate these new findings from the bench to the bedside. Finally yet importantly, a new frontier in epilepsy research is represented by the observation that specific small noncoding RNAs, namely miRNAs, may regulate GABAAR function paving the road to therapeutic approaches based on the modulation of gene expression. CONCLUSION: Here, we review key physiological, neuropathological and functional studies that altogether strengthen the role of modulation of GABAARs function as therapeutic target. The discovery of the novel molecular mechanisms underlying the GABAergic transmission in epilepsy represents another heavy piece in the "epileptic puzzle". Even if GABAAR is an old story in the pharmacology of the epilepsy, the reviewed findings suggest that new players in the scenario need to be considered.