Role of the endocannabinoid system in fragile X syndrome: potential mechanisms for benefit from cannabidiol treatment

Multiple lines of evidence suggest a central role for the endocannabinoid system (ECS) in the neuronal development and cognitive function and in the pathogenesis of fragile X syndrome (FXS). This review describes the ECS, its role in the central nervous system, how it is dysregulated in FXS, and the potential role of cannabidiol as a treatment for FXS. FXS is caused by deficiency or absence of the fragile X messenger ribonucleoprotein 1 (FMR1) protein, FMRP, typically due to the presence of >200 cytosine, guanine, guanine sequence repeats leading to methylation of the FMR1 gene promoter. The absence of FMRP, following FMR1 gene-silencing, disrupts ECS signaling, which has been implicated in FXS pathogenesis. The ECS facilitates synaptic homeostasis and plasticity through the cannabinoid receptor 1, CB₁, on presynaptic terminals, resulting in feedback inhibition of neuronal signaling. ECS-mediated feedback inhibition and synaptic plasticity are thought to be disrupted in FXS, leading to overstimulation, desensitization, and internalization of presynaptic CB₁ receptors. Cannabidiol may help restore synaptic homeostasis by acting as a negative allosteric modulator of CB₁, thereby attenuating the receptor overstimulation, desensitization, and internalization. Moreover, cannabidiol affects DNA methylation, serotonin 5HT_1A signal transduction, gamma-aminobutyric acid receptor signaling, and dopamine D₂ and D₃ receptor signaling, which may contribute to beneficial effects in patients with FXS. Consistent with these proposed mechanisms of action of cannabidiol in FXS, in the CONNECT-FX trial the transdermal cannabidiol gel, ZYN002, was associated with improvements in measures of social avoidance, irritability, and social interaction, particularly in patients who are most affected, showing ≥90% methylation of the FMR1 gene.

A randomized, controlled trial of ZYN002 cannabidiol transdermal gel in children and adolescents with fragile X syndrome (CONNECT-FX)

BACKGROUND

Fragile X syndrome (FXS) is associated with dysregulated endocannabinoid signaling and may therefore respond to cannabidiol therapy.

DESIGN

CONNECT-FX was a double-blind, randomized phase 3 trial assessing efficacy and safety of ZYN002, transdermal cannabidiol gel, for the treatment of behavioral symptoms in children and adolescents with FXS.

METHODS

Patients were randomized to 12 weeks of ZYN002 (250 mg or 500 mg daily [weight-based]) or placebo, as add-on to standard of care. The primary endpoint assessed change in social avoidance (SA) measured by the Aberrant Behavior Checklist-Community Edition FXS (ABC-C_FXS) SA subscale in a full cohort of patients with a FXS full mutation, regardless of the FMR1 methylation status. Ad hoc analyses assessed efficacy in patients with ≥ 90% and 100% methylation of the promoter region of the FMR1 gene, in whom FMR1 gene silencing is most likely.

RESULTS

A total of 212 patients, mean age 9.7 years, 75% males, were enrolled. A total of 169 (79.7%) patients presented with ≥ 90% methylation of the FMR1 promoter and full mutation of FMR1. Although statistical significance for the primary endpoint was not achieved in the full cohort, significant improvement was demonstrated in patients with ≥ 90% methylation of FMR1 (nominal P = 0.020). This group also achieved statistically significant improvements in Caregiver Global Impression-Change in SA and isolation, irritable and disruptive behaviors, and social interactions (nominal P-values: P = 0.038, P = 0.028, and P = 0.002). Similar results were seen in patients with 100% methylation of FMR1. ZYN002 was safe and well tolerated. All treatment-emergent adverse events (TEAEs) were mild or moderate. The most common treatment-related TEAE was application site pain (ZYN002: 6.4%; placebo: 1.0%).

CONCLUSIONS

In CONNECT-FX, ZYN002 was well tolerated in patients with FXS and demonstrated evidence of efficacy with a favorable benefit risk relationship in patients with ≥ 90% methylation of the FMR1 gene, in whom gene silencing is most likely, and the impact of FXS is typically most severe.

TRIAL REGISTRATION

The CONNECT-FX trial is registered on Clinicaltrials.gov (NCT03614663).

Safety and Tolerability of Transdermal Cannabidiol Gel in Children With Developmental and Epileptic Encephalopathies: A Nonrandomized Controlled Trial

IMPORTANCE

Developmental and epileptic encephalopathies (DEEs) are the most severe group of drug-resistant epilepsies. Alternatives to oral therapies are urgently needed to reduce seizures and improve developmental outcomes and comorbidities in this medically complex population.

OBJECTIVE

To assess the safety and tolerability of cannabidiol (CBD) transdermal gel in children with DEEs and to evaluate seizure frequency, sleep, and quality of life.

DESIGN, SETTING, AND PARTICIPANTS

This nonrandomized controlled trial was conducted in 2 centers in Australia and New Zealand from April 2018 to July 2019. Children and adolescents aged 3 to 18 years with DEEs who were receiving a stable regimen of 1 to 4 antiseizure medications were eligible for this study. After 1-month baseline and titration periods, patients entered a 5.5-month flexible-dosing maintenance period for a total of 6.5 months of treatment. Data were analyzed throughout the 6.5-month treatment period.

INTERVENTIONS

Twice-daily applications of CBD transdermal gel at doses of 125 to 500 mg for 6.5 months.

MAIN OUTCOMES AND MEASURES

Safety and tolerability assessments included adverse events (AEs) and examination of skin. The outcome for seizures was the median percentage change from baseline in monthly (28-day) seizure frequency of focal impaired awareness seizures (FIAS) and tonic-clonic seizures (TCS) over 6.5 months.

RESULTS

Of 48 patients (mean [SD] age, 10.5 [3.8] years; 26 [54%] boys), 29 (60%) had at least 1 treatment-related AE over 6.5 months; 44 of 46 treatment-related AEs (96%) were mild or moderate. Treatment-related AEs that occurred in at least 5% of patients were application-site dryness, application-site pain, and somnolence (each reported by 4 patients [8%]). The only treatment-related gastrointestinal AE was diarrhea, reported in a single patient. CBD treatment was associated with reductions in FIAS and TCS frequency. Analysis of the 33 patients with FIAS and TCS showed a median (interquartile range) monthly reduction in seizures of 58% (-5.3% to 81.8%) at 5 months and 43.5% (-23.8% to 57.5%) over the entire 6.5-month study period. Parents and caregivers noted improvements in social or interpersonal engagement and irritability (33 of 43 [77%] participants); alertness, energy, and sleep (23 of 43 [53%]); and cognition or concentration (20 of 43 [47%]).

CONCLUSIONS AND RELEVANCE

In this study, CBD transdermal gel was safe, well tolerated, and was associated with reductions in FIAS and TCS frequency and disease burden.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: ACTRN12618000516280.

A phase 1/2, open-label assessment of the safety, tolerability, and efficacy of transdermal cannabidiol (ZYN002) for the treatment of pediatric fragile X syndrome

Background

Fragile X syndrome (FXS) is characterized by a range of developmental, neuropsychiatric, and behavioral symptoms that cause significant impairment in those with the disorder. Cannabidiol (CBD) holds promise as a potential treatment for FXS symptoms due to its safety profile and positive effects on a number of emotional and behavioral symptoms associated with FXS. The aim of the current study was to evaluate the safety, tolerability, and initial efficacy of ZYN002, a transdermal CBD gel, in a pediatric population with FXS.

Methods

Twenty children and adolescents (aged 6–17 years) with a diagnosis of FXS (confirmed through molecular documentation of FMR1 full mutation) were enrolled in an open-label, multi-site, trial of ZYN002. Transdermal CBD gel was administered twice daily for 12 weeks, titrated from 50 mg to a maximum daily dose of 250 mg. The primary efficacy endpoint was change from screening to week 12 on the Anxiety, Depression, and Mood Scale (ADAMS). Secondary endpoint measures included the Aberrant Behavior Checklist—Community for FXS (ABC-C_FXS), Pediatric Anxiety Rating Scale (PARS-R), Pediatric Quality of Life Inventory (PedsQL™), three Visual Analogue Scales (VAS), and the Clinical Global Impression Scale—Severity (CGI-S) and Improvement (CGI-I).

Results

The majority of treatment-emergent AEs (reported by 85% of participants) were mild in severity (70%), and no serious adverse events were reported. There was a statistically significant reduction in ADAMS total score from screening to week 12 and significant reductions on nearly all other secondary endpoints, including all ADAMS subscales (except depressed mood), all ABC-C_FXS subscale scores (e.g., social avoidance, irritability), PARS-R total severity score, and PedsQL total score.

Conclusions

ZYN002 was well tolerated and produced clinically meaningful reductions in anxiety and behavioral symptoms in children and adolescents with FXS. These findings support further study of ZYN002 in a randomized, well-controlled trial for the treatment of behavioral symptoms of FXS.

Trial registration

ANZCTR, ACTRN12617000150347 Registered 27 January 2017

Conversion of Cannabidiol Following Oral Administration: Authors' Response to Grotenhermen et al. DOI: 10.1089/can.2016.0036

In a commentary, Grotenhermen, Russo, and Zuardi questioned not only the clinical relevance but also the conclusions of a recently published study by Merrick et al. on the conversion of cannabidiol (CBD) to delta-8 and delta-9-tetrahydrocannabinol (THC) in simulated gastric fluid. In response, this article aims to provide a thorough review of the in vitro and in vivo studies of gastric CBD conversion as well as potential consequences resulting from such conversion. Findings highlight (1) consistent evidence over the past half century of gastric conversion of CBD, (2) evidence from human studies, indicating the importance of testing for THC metabolites as well as a number of other cannabinoids in the detection of such conversion, and (3) THC-like effects after administration of oral CBD in humans that may not only stem from CBD's conversion to THC, but also its conversion to 9α-hydroxy-hexahydrocannabinol and 8α-hydroxy-iso-hexahydrocannabinol. These findings, coupled with a number of limitations in the existing literature, point to the need for large-scale human studies, specifically designed to explore gastric conversion and potential THC-like side effects after oral administration of CBD.

Identification of Psychoactive Degradants of Cannabidiol in Simulated Gastric and Physiological Fluid

Introduction: In recent research, orally administered cannabidiol (CBD) showed a relatively high incidence of somnolence in a pediatric population. Previous work has suggested that when CBD is exposed to an acidic environment, it degrades to Δ⁹-tetrahydrocannabinol (THC) and other psychoactive cannabinoids. To gain a better understanding of quantitative exposure, we completed an in vitro study by evaluating the formation of psychoactive cannabinoids when CBD is exposed to simulated gastric fluid (SGF).

Methods: Materials included synthetic CBD, Δ⁸-THC, and Δ⁹-THC. Linearity was demonstrated for each component over the concentration range used in this study. CBD was spiked into media containing 1% sodium dodecyl sulfate (SDS). Samples were analyzed using chromatography with UV and mass spectrometry detection. An assessment time of 3 h was chosen as representative of the maximal duration of exposure to gastric fluid.

Results: CBD in SGF with 1% SDS was degraded about 85% after 60 min and more than 98% at 120 min. The degradation followed first-order kinetics at a rate constant of −0.031 min⁻¹ (R²=0.9933). The major products formed were Δ⁹-THC and Δ⁸-THC with less significant levels of other related cannabinoids. CBD in physiological buffer performed as a control did not convert to THC. Confirmation of THC formation was demonstrated by comparison of mass spectral analysis, mass identification, and retention time of Δ⁹-THC and Δ⁸-THC in the SGF samples against authentic reference standards.

Conclusions: SGF converts CBD into the psychoactive components Δ⁹-THC and Δ⁸-THC. The first-order kinetics observed in this study allowed estimated levels to be calculated and indicated that the acidic environment during normal gastrointestinal transit can expose orally CBD-treated patients to levels of THC and other psychoactive cannabinoids that may exceed the threshold for a physiological response. Delivery methods that decrease the potential for formation of psychoactive cannabinoids should be explored.

A sumatriptan iontophoretic transdermal system for the acute treatment of migraine

OBJECTIVE

Gastrointestinal symptoms, such as nausea and vomiting, occur almost universally at one time or another in patients during a migraine attack. One third of patients who experience migraine-related nausea report that this symptom interferes with their ability to take oral medications. The sumatriptan iontophoretic transdermal system (NuPathe Inc., Conshohocken, PA, USA) uses proprietary technology to circumvent the gastrointestinal tract while delivering triptan therapy. This phase III randomized, double-blind, placebo-controlled trial evaluated the efficacy and tolerability of this system for the acute treatment of migraine.

METHODS

Patients were randomized to treat a single moderate-to-severe migraine attack with the sumatriptan iontophoretic transdermal system or placebo. The primary end point was the proportion of patients who were headache pain-free 2 hours after patch activation. Other end points included the proportions of patients who reported headache pain relief, and freedom from nausea, photophobia, and phonophobia; rescue medication use; and tolerability.

RESULTS

Four hundred sixty-nine patients were treated. Significantly more patients treated with the sumatriptan iontophoretic transdermal system compared with placebo experienced freedom from headache pain, nausea, photophobia, and phonophobia 2 hours after patch activation, experienced rapid and sustained headache pain relief, and used less rescue medication. Treatment-emergent adverse events were reported by 50% and 44% of patients treated with the sumatriptan iontophoretic transdermal system and placebo, respectively. Most events were transient mild-to-moderate application-site reactions.

CONCLUSIONS

The sumatriptan iontophoretic transdermal system is effective and well tolerated, and may be particularly useful in patients with migraine-related gastrointestinal symptoms such as nausea.

Zelrix: a novel transdermal formulation of sumatriptan

OBJECTIVE

This study evaluated the pharmacokinetic and tolerability profiles of Zelrix (NuPathe Inc., Conshohocken, PA, USA), the novel formulation of sumatriptan (formerly known as NP101).

BACKGROUND

Migraine is an episodic headache disorder characterized by a combination of neurological, gastrointestinal, and autonomic symptoms. Gastrointestinal disturbances, including nausea, vomiting, and gastric stasis are common and can result in significant impact on treatment. Triptans are 5-hydroxytriptanime(1B/1D) agonists that work on the trigeminal nerve that is activated during migraine. All triptans approved for use in the US are currently available as oral formulations; however, this may not be the ideal route of administration for many migraineurs. Sumatriptan is also available as a nasal spray and subcutaneous (s.c.) injection. Therefore, the need to develop improved methods for noninvasive parenteral delivery of triptans remains high.

METHODS

This was a Phase I, single-center, open-label, crossover study that assessed the pharmacokinetic properties of a single dose of sumatriptan delivered using an iontophoretic transdermal patch in comparison with oral, injection, and nasal delivery. Subjects were healthy male and female volunteers who received each of 5 treatments: sumatriptan 100 mg oral tablets, sumatriptan 6 mg s.c., sumatriptan 20 mg nasal spray, Zelrix I (transdermal patch with 3 g of gel solution delivering 6 mg of sumatriptan transdermally), or Zelrix II (transdermal patch containing 2.6 g of gel solution delivering 6 mg of sumatriptan).

RESULTS

The C(max) for Zelrix was reduced to 30% and 28% of the sumatriptan s.c. dose, thereby reducing the risk of triptan-like sensations associated with high peak plasma concentrations. Plasma concentrations for Zelrix I and Zelrix II were intermediate between those for oral and nasal sumatriptan doses tested. Transdermal patch delivery of sumatriptan to the systemic circulation reached plasma concentrations of 10 ng/mL within about 30 minutes. The mean drug delivery of Zelrix I and II was 6.11 mg (confidence intervals [CI] 5.33-6.88) and 6.09 mg (CI 5.52-6.66), respectively. The AUC(0-inf) was approximately 99% for the Zelrix I patch and 100% for the Zelrix II patch as compared with sumatriptan 6 mg s.c. dose. Both doses of sumatriptan transdermal patches were well tolerated. Skin reactions at the patch site were mild and erythema resolved in most subjects within 48-72 hours.

CONCLUSIONS

The results from this study show that sumatriptan administration using a novel iontophoretic transdermal technology delivers plasma levels within the range for nasal spray, tablet, and injectable sumatriptan. Zelrix I and II were well tolerated and adverse events were mild and transient. Transdermal delivery of sumatriptan using the SmartRelief iontophoretic technology may prove beneficial for a large segment of the migraine population based upon fast, consistent delivery of drug and avoidance of common gastrointestinal disturbances associated with migraine.

A Unique Iontophoretic Patch for Optimal Transdermal Delivery of Sumatriptan

PURPOSE

Migraines affect approximately 10% of the adult population worldwide. The purpose of this study was to assess the pharmacokinetic and safety profile of a novel iontophoretic sumatriptan delivery system, NP101, which uses an electrical current to propel sumatriptan across intact skin and into underlying tissue. Four unique prototype iontophoretic sumatriptan patch conditions were compared to a 6 mg subcutaneous injection and an oral 50 mg tablet of sumatriptan succinate.

MATERIALS AND METHODS

This was a randomized, single-center, single-dose, six-period Phase I study.

RESULTS

Patches were well tolerated with fewer adverse events than the subcutaneous injection. Adverse events that were more prevalent for NP101 than other formulations included localized sensations and reactions at the patch site. A linear relationship was observed between total applied current and sumatriptan delivery. Patches delivering 6 and 12 mA per h yielded favorable sumatriptan systemic profiles, delivering drug at a rate that maintained plasma levels above the target level (> or = 10 ng/ml) for greater than 7 h.

CONCLUSIONS

This study met the initial objective to define the dose-current relationship in humans as well as delimiting specific current and current density targets for a well tolerated patch design that can deliver therapeutic drug levels for longer periods than currently possible.

AA2500 testosterone gel normalizes androgen levels in aging males with improvements in body composition and sexual function

Testosterone replacement in hypogonadal men improves body composition, mood, and sexual functioning. In this 90-d study, we compared the pharmacokinetics and treatment effectiveness of a topical testosterone gel (AA2500) at two concentrations, 50 mg/d and 100 mg/d, to a testosterone patch and placebo gel in 406 hypogonadal men. Pharmacokinetic profiles were obtained, body composition was measured, and mood and sexual function were monitored. AA2500 treatments resulted in dose-dependent improvements in all pharmacokinetic parameters, compared with testosterone patch and placebo. Mean average concentrations at d 90 T were 13.8, 17.1, 11.9, and 7.3 nmol/liter for 50 mg/d AA2500, 100 mg/d AA2500, testosterone patch, and placebo, respectively. At d 90, the 100 mg/d AA2500 treatment improved lean body mass by 1.7 kg and percentage of body fat by 1.2% to a significantly greater degree than either control treatment. Significant improvements in spontaneous erections, sexual desire, and sexual motivation were also evidenced with the 100 mg/d AA2500 dose in comparison with placebo. Testosterone gel was well tolerated; however, the testosterone patch resulted in a high rate of application site reactions. Overall, AA2500 is an effective, well tolerated treatment for hypogonadism.

Evaluation of the pharmacokinetic profiles of the new testosterone topical gel formulation, Testim, compared to AndroGel

A two-period, randomized, complete crossover study was performed to evaluate the pharmacokinetic profiles of Testim (AA2500), a new 1% testosterone topical gel formulation, compared to AndroGel, an already available 1% testosterone topical gel. Twenty-nine hypogonadal subjects received a single dose (50 mg testosterone) of each formulation seven days apart. C(max) estimates for total testosterone, dihydrotestosterone and free testosterone were greater (30, 19 and 38%, respectively) following the application of Testim compared to AndroGel. Similarly, AUC(0-24) estimates for total testosterone, dihydrotestosterone, and free testosterone were greater (30, 11 and 47%, respectively) following the application of Testim compared to AndroGel. Confidence intervals for C(max) and AUC(0-24) were not wholly contained within the bioequivalence limits for testosterone, therefore Testim trade mark and AndroGel are not bioequivalent with Testim providing higher serum levels and greater bioavailability than AndroGel.