Product labeling accuracy and contamination analysis of commercially available cannabidiol product samples.

Background and objective: Commercially available cannabidiol (CBD) products are increasingly being used for medicinal purposes, including for the treatment of various neurological conditions, but there are growing concerns around adherence to quality control measures that protect consumers. This study was conducted to assess the purity and label accuracy of commercially available CBD products. Methods: Commercially available CBD products were chosen from the open stream of commerce in the United States based on formulations as a tincture, gummy, vape, or topical product. Cannabinoid concentrations were analyzed to verify label accuracy including "full spectrum," "broad spectrum," and "CBD isolate" claims on the product label. Analysis for the presence of contaminants included evaluation for heavy metals, pesticides, and residual solvents. Labeled and actual total amounts of CBD and levels of impurities such as heavy metals, residual solvents, and pesticides were measured. Results: A total of 202 CBD products (100 tinctures, 48 gummies, 34 vape products, and 20 topicals) were chosen to represent a broad sample in the United States. Of the products tested (full spectrum, n = 84; broad spectrum, n = 28; CBD isolate, n = 37), 26% did not meet the definition for product type claimed on the packaging. The majority of products (74%) deviated from their label claim of CBD potency by at least 10%. Heavy metals were detected 52 times across 44 of the 202 products tested, with lead being the most prevalent heavy metal. Residual solvents were detected 446 times across 181 of 202 products, with the highest concentrations reported for hexane, m/p-xylene, methanol, and o-xylene. Of 232 pesticides tested, 26 were found 55 times across 30 products. A total of 3% of heavy metals, 1% of residual solvents, and 1% of pesticides violated >1 regulatory threshold. Discussion: This study demonstrated that the majority of commercially available CBD products tested within the current study are inaccurately labeled. Heavy metals, residual solvents, and pesticides were found in several products, some of which violated regulatory thresholds. Thus, uniform compliance with CBD quality control measures is lacking and raises consumer protection concerns. Improved regulatory oversight of this industry is recommended.

Zonisamide: A Comprehensive, Updated Review for the Clinician.

Purpose of Review: Zonisamide (ZNS) was first approved in the United States in 2000 for the adjunctive treatment of patients aged 16 years or older with partial (focal) seizures. Although ZNS has been proven to treat multiple seizure types, it has been largely underutilized in US clinical practice. Recent Findings: Published literature demonstrated that antiseizure medications (ASMs) acting on Na+ and Ca2+ channels may add beneficial effects in many seizure types by reducing seizure frequency and leading to overall improvements. In addition, effects of ZNS may lead to clinical improvements in Parkinson disease, alcohol and sleep disorders, pain, and migraine. ZNS is available in multiple formulations and is a safe and effective, broad spectrum ASM. Summary: The purpose of this review was to provide an update to what is known about the efficacy of ZNS and where it shows benefits in the treatment of patients with epilepsy and other CNS disorders through its many unique mechanisms of action.

Lamotrigine use and potential for adverse cardiac effects: A retrospective evaluation in a Veteran population.

OBJECTIVE: To identify the impact of lamotrigine (LTG) on cardiac rhythm and conduction abnormalities for Veterans, an especially vulnerable population. BACKGROUND: In October 2020 the US Food and Drug Administration (FDA) added a new warning to the label of lamotrigine (Lamictal™) regarding its potential to cause cardiac rhythm and conduction abnormalities [1]. This warning came following in vitro data which suggested Class IB antiarrhythmic effects occurring at clinically achievable concentrations of lamotrigine [2]. However, it is unclear whether the in vitro findings will result in adverse clinical outcomes. Our objective was to assess for evidence for adverse clinical outcomes in a vulnerable population and examine for subtler signs of an association between lamotrigine and cardiac rhythm disturbances. METHODS: A retrospective chart review was conducted using records between 10-01-2017 and 07-06-2021, identifying patients at the William S. Middleton Memorial Veterans Hospital who were prescribed lamotrigine. Data collected included: dates of lamotrigine initiation or discontinuation, lamotrigine dosing over the time of the prescription and maximum lamotrigine dose, any cardiac-related ICD-10-CM codes or a history of a cardiology appointment, EKGs with any abnormalities or changes, any concomitantly prescribed medications with known potential to cause cardiac abnormalities, any cardiac deaths. This retrospective chart review was approved by the University of Wisconsin-Madison Institutional Review Board. RESULTS: Two hundred and thirty-three (189 male) patients with a lamotrigine prescription and 41.2 % (n = 96) of these patients had an EKG performed while prescribed lamotrigine. The average age of patients was 64.3 ± 13.0 (range 29 to 90) years and mean maximum lamotrigine daily dose was 250.8 ± 148.2 mg (range 25 to 800 mg). Nearly half (47.9 %, 46/96) of the patients were prescribed a concomitant sodium channel blocking medication in addition to lamotrigine. Eighty-four of the patients (87.5 %, 84/96) had a cardiac diagnosis, while 12 (12.5 %, 12/96) did not. A total of 12 deaths occurred within the review period, with two cardiac deaths from congestive heart failure. Four cases did not have information on cause of death. No LTG-associated cardiac adverse effects were noted as part of clinical care, though rash was noted in 5 cases. A total of 7 (7.3 %, 7/96) patients were found to have EKG abnormalities potentially related to lamotrigine, including 7.1 % (6/84) of those with a cardiac diagnosis and 8.3 % (1/12) of those without a cardiac diagnosis. CONCLUSIONS: While recent FDA warnings have suggested caution regarding cardiac complications associated with lamotrigine based on in vitro studies, the clinical implications are uncertain. Despite selecting a particularly vulnerable population, this retrospective chart review did not identify any deaths due to cardiac rhythm or conduction causes, nor demonstrate unambiguous cardiac complications related to lamotrigine. Even using permissive criteria (including any prolonged PR or QTc) to examine for subtle effects, only a low incidence (<10 %) of potential complications was found. Broader implications of this study are limited by the number of patients included and the retrospective nature of the study. Therefore, further studies are warranted to evaluate a link between cardiac complications and the use of lamotrigine, including the role of concomitant medications such as other sodium channel blocking agents and psychotropic medications.

Patterns of psychotropic drug use in veterans with epilepsy: Do drug interactions matter?

RATIONALE: Patients with epilepsy are likely to suffer from psychiatric comorbidities, including depression and anxiety. They often require treatment with multiple psychotropic drugs (PDs). While it is clear that CYP-inducing ASMs (EIASMs) can increase the oral clearance of multiple medications (thus lowering systemic exposure), it is less clear that all PK interactions are clinically meaningful (e.g. lower efficacy). As a first step in addressing this issue, this study sought to quantify the potential impact of ASM choice, whether EIASM or non-inducer (NIASM), on surrogate markers of suggestive of clinical use, including resultant antidepressant (AD) or antipsychotic (AP) dose, frequency of combination use of AD & AP, and number of multiple drug switches of PDs. Our hypothesis is that because of PK interactions, EIAED treatment would be associated with higher psychotropic drug doses, more frequent Rx adjustments and poly psychotropic comedication, all in order to optimize therapeutic response. METHODS: Using VA pharmacy and national encounter databases, veterans with epilepsy were identified based on having a seizure diagnosis and being prescribed concomitantly an ASM and a psychotropic drug for at least 365 days between 10/1/2010 and 9/30/2014. Patients for whom psychotropic drugs were prescribed any time between beginning and end prescriptions dates of ASMs were considered. Among those, patients receiving both an EIASM + NEIASM concomitantly were categorized with the EIASM group. Patients were evaluated for AD only, AP only and both (AD & AP). To compute average drug doses per day, averages for each patient were computed and averaged again. Multiple drug switches were defined to be for patients who had been prescribed more than three psychotropic drugs during the observation period. Pearson's Chi-Square test was used to compare relative proportions of AD, AP and AD + AP in both groups. RESULTS: In all, 16,188 patients were identified (57.0% on EIASM, 43.0% on NIASM) with a mean age of 58.7 years (91.2% male). A larger proportion of patients on EIASM received mono treatment with any psychotropic drug, as compared to NIASM (42.0% vs 36.1%). Among all, 59.6% received AD only, 6.5% received AP only, and 33.8% received both concurrently. Of EIASM, 62.5% were on AD, 5.9% on AP, and 31.7% on both AP & AD. For NIASM, 55.9% received AD, 7.4% AP, and 36.7% on AD & AP.Chi-square showed that the distribution of PD was statistically different between EIASM and NIASM groups. Z tests showed that each difference (AD, AP and both) in proportions was statistically significant (p values (4 tests, one Chi-square, 3 Z tests <0.001) between EIASM vs NIASM. Interestingly, mean doses of AD or AP did not appear to differ between ASM groups. CONCLUSIONS: Concurrent psychotropic drug use is quite common in the VA population with epilepsy, and a large number of patients still receive enzyme-inducing ASMs that may complicate other medical therapies. Interestingly, in seeming contradiction to our hypothesis, mean daily doses of either AD or AP did not appear to differ between inducers vs non-inducers. Similarly, use of polytherapy, and/or multiple trials of various psychotropic drugs did not appear increased in the CYP-induced group. In fact, combination therapy of AD + AP was higher in NIASM than EIASM. These data suggest that perhaps these types of PK interactions may not in fact result in meaningful clinical differences. Since the present analyses did not include clinical psychiatric measures, future analyses examining direct clinical outcomes are clearly warranted.

Real-world, long-term evaluation of the tolerability and therapy retention of Epidiolex® (cannabidiol) in patients with refractory epilepsy.

OBJECTIVE: Epidiolex® (CBD) is FDA-approved for seizures associated with Lennox-Gastaut syndrome (LGS), Dravet syndrome (DS), and tuberous sclerosis complex (TSC). Phase III studies suggest that certain adverse effects (AEs), possibly linked to pharmacokinetic/pharmacodynamic (PK/PD) interactions may be therapy-limiting. We sought to identify these factors that contribute to treatment success and retention of therapy. METHODS: A single-center, retrospective review of patients with refractory epilepsy taking Epidiolex® was performed. Kaplan-Meier analysis was performed to describe Epidiolex® retention, as a measure of overall effectiveness. RESULTS: One hundred and twelve patients were screened; 4 were excluded due to loss to follow-up or never starting Epidiolex®. Of 108 patients, mean age was 20.3 years (13.1, range 2 to 63), and 52.8% were female. Mean initial and maintenance doses were 5.3 mg/kg/day (1.3) and 15.3 mg/kg/day (5.8), respectively. At the final evaluation, 75% of patients remained on Epidiolex®. The 25th percentile for discontinuation was 19 months. 46.3% of patients experienced at least one treatment-emergent adverse effect (TEAE) with 14.5% d/c Epidiolex® due to treatment emerging adverse effects (TEAE). The most common reasons for discontinuation were lack of efficacy (37%), increased seizure activity (22%), worsened behavior (22%), and sedation (22%). One out of 27 discontinuations was due to liver function test (LFT) elevations (3.7%). At initiation, 47.2% were concurrently taking clobazam, and 39.2% of those patients had an initial clobazam dose decrease. 53% of patients were able to either discontinue or lower the dose of at least one other antiseizure medication. SIGNIFICANCE: Epidiolex® is generally well-tolerated and the majority continued long-term treatment. Patterns of adverse effects were similar to clinical trials, however gastrointestinal complaints, and significant LFT elevations were less common. Our data suggest most patients discontinue within the first several months of treatment and suggest that further studies designed to evaluate early identification and potential mitigation of adverse effects and including drug interactions are warranted.

PaxlovidTM Information From FDA and Guidance for AES Members.

This American Epilepsy Society (AES) official statement provides information and preliminary guidance to Society members related to the U.S. Food & Drug Administration (FDA) December 22, 2021 Emergency Use Authorization for Paxlovid™ for the oral treatment of mild to moderate COVID-19 in adults and children (≥12 years and weighing ≥40 kg). Paxlovid is likely to be widely prescribed, and important considerations for patients on antiseizure medications (ASMs) include key contraindications and potential toxicity or dose adjustments while taking Paxlovid. This statement highlights concerns and provides information about their pharmacologic basis. Of particular concern, concomitant use of Paxlovid with the ASMs carbamazepine, phenobarbital, phenytoin, and primidone is contraindicated, because they are strong inducers of the CYP3A4 isozyme that metabolizes Paxlovid and thereby could cause loss of virologic response and development of resistance. Alternate oral or intravenous COVID-19 treatments should be considered. A second concern is that Paxlovid may increase the plasma concentrations of many ASMs, because it inhibits the CYP3A4 isozyme. ASMs that are metabolized, at least in part, by CYP3A4 include cannabidiol, carbamazepine, clobazam, clonazepam, diazepam, ethosuximide, everolimus, felbamate, lacosamide, midazolam, oxcarbazepine, perampanel, stiripentol, tiagabine, and zonisamide. Patients receiving these medications may warrant closer monitoring while being treated with Paxlovid.

Rescue Treatments for Seizure Clusters.

Treatment of seizure clusters endeavors to prevent additional seizures and avoid progression to conditions such as prolonged seizures and status epilepticus. Rescue therapies are key components of seizure action plans (SAPs) for individuals with seizure clusters. Three rescue therapies are approved in the United States for the treatment of seizure clusters: diazepam rectal gel, midazolam nasal spray, and diazepam nasal spray. Diazepam rectal gel is an effective rescue therapy for seizure clusters, though adults and adolescents may have social reservations regarding its administration. Intranasal delivery of midazolam or diazepam is a promising alternative to rectal administration because these formulations offer easy, socially acceptable administration exhibit a rapid onset, and allow for the possibility of self-administration. Off-label benzodiazepines, such as orally disintegrating lorazepam and intranasal use of an intravenous (IV) formulation of midazolam via nasal atomizer, are less well characterized regarding bioavailability and tolerability compared with approved agents.

Analysis of cannabidiol (CBD) and THC in nonprescription consumer products: Implications for patients and practitioners.

PURPOSE: Cannabidiol products remains largely unregulated in the US. Unlike the Rx formulation of CBD [EpidiolexR], little information is available regarding labeling accuracy (does the product contain what the label says it does), lot to lot variability, nor long-term product stability. Understanding these properties are fundamental if these products are to be used in patients with epilepsy, where product variability of traditional AEDs has been suspected to result in inadequate seizure control. Therefore, we analyzed commercial CBD products, including oils, aqueous products (i.e., beverages), and various Other products for cannabinoid content vs label claims and stability under United States Pharmacopeia (USP) standards. METHOD: Samples were diluted and analyzed by HPLC for CBD, THC, and CBN concentrations in order to assess product label accuracy. Products with <90% of label claim CBD were denoted over-labeled, products with >110% of label claim CBD were denoted under-labeled, and products between 90% and 110% of label claim CBD were denoted appropriately labeled, per USP standards. RESULTS: Among commercial CBD Oils (n = 11), mean CBD concentration vs label claim was 91.56% [95% CI, 66.02-117.10%], although 18.18% of oils (n = 2) made nonspecific label claims of "hemp extract" in lieu of CBD. Among all oils, 36.36% (n = 4) were appropriately labeled, another 36.4% (n = 4) of all oils were under-labeled, maximum 128.3% label claim, and finally, 9.09% (n = 1) of oils were over-labeled. The remaining 18.18% (n = 2) of oils lacked specific CBD label claims, minimum of 0.3 mg CBD per 1-ml "dose". THC was detected in 54.55% (n = 6) of oils with a maximum concentration of 0.2% w/v and a minimum concentration of 0.036% w/v. Cannabinol was detectable in only 9.1% (n = 1) of products at a concentration of 0.00465% w/v. Among aqueous products (n = 21) tested, only 66.67% (n = 14) gave specific CBD label claims, with mean CBD concentration vs label claim of 59.93% [95% CI, 38.24-81.63%]. Only 7.14% (n = 1) of aqueous products with a label claim were appropriately labeled, 14.29% (n = 2) were found to be under-labeled, and 78.57% (n = 11) over-labeled. THC was detected in 23.81% (n = 5) of aqueous products tested with a maximum THC concentration of 0.0005% w/v, and a minimum concentration of 0.0002% w/v. Cannabinol was detected in 9.52% (n = 2) of aqueous products, both at a concentration of 0.0015% w/v. "Other" products (n = 7) tested ranged from chocolate bars to transdermal patches. Some 42.86% (n = 3) gave specific CBD label claims, with mean CBD concentration vs label claim of 67.01% [95% CI, 0.87-133.14%]. Among these three "Other" products with specific label claims, 33% (n = 1) was appropriately labeled, and 66.67% (n = 2) were over-labeled, with CBD concentrations vs label claim ranging from a minimum of 39.30% to a maximum of 101.99%. The remaining 57.14% (n = 5) of "Other" products tested made nonspecific CBD label claims, denoting CBD content in terms of "full spectrum hemp extract" or "activated cannabinoids". One such product was labeled with a "40-50-mg CBD" range instead of a single, specific value. Tetrahydrocannabinol was detected in 71.43% (n = 5) of Other products tested with a maximum concentration of 0.0046% w/w, and a minimum concentration of 0.0008% w/w. Cannabinol was detected in 14.3% (n = 1) of Other products at a concentration of 0.0001% w/w. CONCLUSION: We demonstrate that commercial CBD products, especially aqueous beverages, can show inconsistent labeling, vary largely from their label claims should they make them, and show lot-to-lot variability making dosing unpredictable.

Extending the reach of science - Talk in plain language.

There has been increasing interest by the general public to read and share mainstream medical and scientific literature. Consequently, more and more medical journals are adopting strategies to make complex literature more accessible to the lay public. One such strategy is the creation of so called "lay summaries". The benefits of lay summaries can include wider dissemination of knowledge, and is increasingly being recognized as a unique expertise by authors. While on the surface, it may seem to be an easy task to translate scientific literature into a lay summary. However, occasionally authors who are experienced in communicating complex information to a peer group, may struggle with translating their work to an audience with limited medical or scientific background. The objective of this review is to discuss strategies that scientific writers may consider to better facilitate translating scientific literature into lay summaries.

Levetiracetam-associated irritability and potential role of vitamin B6 use in veterans with epilepsy.

OBJECTIVES: Levetiracetam, a commonly prescribed antiseizure medication (ASM), may cause irritability, depression, and anger. The mechanisms underlying these behavioral effects and individual risk factors remain unknown. Mitigation strategies are limited, including discontinuation, supplementation with vitamin B6, or switching to an alternative ASM. Several retrospective studies and anecdotal reports, primarily in pediatric populations, suggest vitamin B6 supplementation may be helpful in reducing levetiracetam-associated irritability. Although data in adult patients is limited, and no data is available for Veterans. The objective of this project was to describe our preliminarily experience with vitamin B6 supplementation for alleviating levetiracetam-associated irritability in male Veterans with epilepsy. METHODS: Retrospective chart reviews were completed for patients who had an active prescription for levetiracetam from the William S. Middleton Memorial Veterans Hospital from January 1, 2015 to June 1, 2020. A total of 26 charts were screened. Patients were excluded if not using vitamin B6 supplementation or if deceased at end of data collection. Baseline characteristics were compared, including age, sex, comorbidities, and concomitant medications. Charts were then reviewed to identify any clinical description of irritability, including subjective assessment of change in symptoms across multiple visits, and scores from standardized instruments including the patient health questionnaire (PHQ-9), generalized anxiety disorder questionnaire (GAD-7), and/or irritability in adult patients with epilepsy (I-EPI) questionnaire. These symptoms and scores were then compared pre- and post-B6 supplementation. RESULTS: Of 22 patients, data was available for 20 (91%). For patients with data available, 9 (45%) showed improved irritability following supplementation with vitamin B6 and 11 (55%) showed no improvement. CONCLUSIONS: This project suggests that vitamin B6 supplementation may have a role in mitigating levetiracetam-associated irritability in a male Veteran population. These results support future prospective controlled studies to assess further the efficacy of this approach and characteristics associated with successful treatment in veterans.

Use of extended-release and immediate-release anti-seizure medications with a long half-life to improve adherence in epilepsy: A guide for clinicians.

Poor adherence to anti-seizure medications (ASMs) is associated with breakthrough seizures and potentially increased toxicity in patients with epilepsy. Extended-release (ER) drugs and immediate-release (IR) drugs with a long half-life (t1/2) that permit once-daily dosing (such as, perampanel, zonisamide, lamotrigine [IR, ER] and topiramate [ER]) have a number of advantages over short t1/2 ASMs that require multiple daily dosing. These advantages include simplification of dosing regimens, reduction in pill burden, and a decrease in the peak-to-trough fluctuations in serum drug concentration that may be associated with a decreased risk of adverse effects and seizures. Such properties have wider implications in improving patient adherence to treatment. This article is intended as a practical guide for clinicians that provides an overview of the features of ER ASMs and long t1/2 IR ASMs that are advantageous in the context of patient adherence and pharmacokinetic "forgiveness" (after missing a dose). In addition, we note that efforts to improve adherence should not depend solely on drug dosing regimens and drug pharmacokinetics, but should be part of a wider strategy that includes therapeutic drug monitoring, improved healthcare provider-patient dialogue, patient education, and the use of "reminder" technology.

Influence of titration of antiseizure medications on treatment selection: Results of an online survey with clinicians in the United States.

INTRODUCTION: Most antiseizure medications (ASM) need to be titrated before the optimal dose is achieved. Titration can last several weeks to months. We assessed the impact titration schedules have on ASM treatment-related decisions in the United States (US). METHODS: An online survey was conducted with different healthcare providers (HCPs) in the US involved in the treatment and management of patients with epilepsy. The survey contained three sections: the first section with screening questions; the second on key factors that influence a HCP's decision-making when selecting treatments for different types of seizures and different treatment lines; and the third on the HCP's knowledge and perceptions regarding ASM titration for the treatment of patients with epilepsy. RESULTS: One-hundred and fifty HCPs (63% neurologists) completed the survey. Most HCPs considered titration schedule to be important, with only 1-3% of HCPs, depending on type of seizure, considering the titration schedule to be "not important at all" when prescribing therapy. Healthcare providers' acceptance of titration increased with shorter durations (≥50% accepted titration periods of ≤2 weeks), and lower number of tablets/capsules per dose (≥50% accepted ≤3 tablets/capsules per dose), doses (≥50% accepted ≤2 doses/day), and steps (≥50% accepted ≤3 steps/dose change). Most HCPs (68-91% depending on type of seizure) considered a titration duration of 6 or more weeks only somewhat acceptable or somewhat or highly unacceptable. Almost all HCPs selected "somewhat familiar", "familiar", or "very familiar" as the attribute that best defines their knowledge level of titration, with only 4% selecting "a little familiar". While 87% of HCPs agreed or strongly agreed that they could easily understand titration schedules, only 27% of them agreed or strongly agreed that patients could easily understand titration schedules and 58% of HCPs considered that adhering to the titration schedule was difficult for patients. Most HCPs agreed or strongly agreed that a complex or long titration schedule renders it difficult to achieve their treatment objectives. CONCLUSIONS: Healthcare providers take into account the duration and complexity of the titration period in their ASM prescribing decision-making and prefer shorter and simpler titration schedules, particularly for patients who are experiencing convulsive seizures and starting monotherapy. There was a clear difference between the HCP's belief in their own ability to understand a titration schedule, and their belief that the patient would be able to follow the titration schedule appropriately.

Coffee and cigarette smoking interactions with lamotrigine.

The objective of this analysis was to determine possible interactions between lamotrigine (LTG) and coffee or cigarette use. As part of the statistical analysis of factors influencing LTG pharmacokinetics (PK) in the Equigen chronic dose study, we collected prospective data from enrolled patients on their use of coffee and cigarettes. Subjects were part of a crossover replication study of generic LTG products with rigorous blood sampling and were instructed to not change their typical consumption of these products for the duration of the study. A total of 35 subjects were enrolled, with 33 subjects having sufficient data for analysis. Higher consumption of coffee was associated with a significantly lower area under the curve (AUC) and maximum concentration (Cmax) of lamotrigine (LTG). Higher cigarette use did not result in a significant change in AUC or Cmax. Coffee, but not cigarette use, either induces LTG metabolism or inhibits LTG absorption.

Bioavailability and safety of diazepam intranasal solution compared to oral and rectal diazepam in healthy volunteers.

OBJECTIVE: The study assesses the bioavailability of diazepam after intranasal administration (diazepam nasal spray) in healthy volunteers. Comparative agents were diazepam rectal gel, which served as the regulatory reference product; and oral diazepam, a product with decades of clinical use. Tolerability of diazepam nasal spray was also assessed. METHODS: This was a phase 1, open-label, randomized, single-dose, three-treatment, three-period, six-sequence crossover study in 48 healthy adult subjects that consisted of a screening period, a baseline period, and an open-label treatment period. Interperiod intervals were at least 28 days. RESULTS: Forty-eight healthy volunteer subjects were enrolled, two of whom discontinued before receiving study medication. For all routes of administration, the onset of diazepam absorption was rapid, with measurable concentrations of drug present by the first sample time point. The tmax (time to reach maximum plasma concentration) was similar for diazepam nasal spray and diazepam rectal gel, both of which were slower than oral diazepam in fasted individuals. Variability (as defined by % coefficient of variation of geometric mean) in peak plasma concentration and area under the curve0-∞ was lowest with oral diazepam, followed by diazepam nasal spray, with diazepam rectal gel showing the greatest variability. Overall, 131 treatment-emergent adverse events (TEAEs) were considered mild (42 subjects, 91.3%), four TEAEs were considered moderate (four subjects, 8.3%), and no TEAEs were considered severe. The most commonly reported TEAE was somnolence at 56.5% (26/46) during diazepam nasal spray treatment, 89.1% (41/46) with the rectal diazepam gel treatment, and 82.6% (38/46) with oral diazepam treatment. No nasal irritation was observed for the majority of the subjects at any time point after administration, with no score higher than 2 ("minor bleeding that stops within 1 minute"). SIGNIFICANCE: Diazepam nasal spray shows predicable pharmacokinetics and represents a potential novel therapeutic approach to control bouts of increased seizure activity (cluster seizures, acute repetitive seizures).

Drug-drug interactions and pharmacodynamics of concomitant clobazam and cannabidiol or stiripentol in refractory seizures.

OBJECTIVE: The goal of this study was to characterize the drug-drug interactions between clobazam and 2 antiseizure drugs, cannabidiol and stiripentol, for treatment of refractory seizures through the use of pharmacokinetic modeling. METHODS: A population pharmacokinetic/pharmacodynamic model was developed to characterize the combined effect of clobazam and its active metabolite, N-desmethylclobazam (i.e., N-clobazam), on seizure protection in patients with Lennox-Gastaut syndrome using data from the phase 3 CONTAIN trial. Drug-drug interactions between clobazam and cannabidiol were examined by comparing model-generated data to data from a study of 13 patients taking concomitant clobazam and cannabidiol. Modeling data were also descriptively compared with studies of patients administered both clobazam and stiripentol. Sedation-related adverse events from CONTAIN were analyzed to determine the exposure-somnolence relationship of clobazam. RESULTS: Exposure-efficacy analysis from the pharmacokinetic/pharmacodynamic model using CONTAIN data indicated that clobazam (half-maximal effective concentration [EC50], 303 ng/mL) was 3 times more potent than N-clobazam (EC50, 899 ng/mL). After administration of clobazam, when both clobazam and N-clobazam concentrations were each 1 to 2 times the EC50 value (clobazam dose, 20 mg), 70.0%-74.9% seizure protection was predicted; when concentrations were >2 times the EC50 value (clobazam dose, 40 mg), 74.0%-96.9% seizure protection was predicted. Generalized additive model analyses demonstrated decreased seizure probability with higher plasma concentration of clobazam. Coadministration of stiripentol and clobazam resulted in increased respective median plasma concentrations of clobazam and N-clobazam (1.1-1.2 times and 5.2-8.2 times) compared with administration of placebo and clobazam. Probability of somnolence significantly increased with age and higher N-clobazam plasma concentration. SIGNIFICANCE: Awareness of drug-drug interactions between clobazam and cannabidiol is needed when adding cannabidiol or stiripentol to a regimen of clobazam or vice versa. Based upon our population pharmacokinetic/pharmacodynamic model, we predict that an increase in N-clobazam levels, which patient data show may enhance efficacy and/or make adverse events such as somnolence more likely.

Vitamin D abnormalities and bone turn over analysis in children with epilepsy in the Western Cape of South Africa.

PURPOSE: The effects of antiseizure medications (ASMs) on bone metabolism is inconsistent. Most studies are in high income settings and none from sub-Saharan Africa. METHODS: A hospital based cross-sectional study in a paediatric epilepsy service with a comparison group assessed vitamin D metabolism. RESULTS: Seventy-five children with epilepsy and 75 comparison group were recruited. Median age for children with epilepsy was 9 years (range 1-17 years) and controls 3 years (range 1-12 years). Vitamin D deficiency occurred in 11(16.2%) children with epilepsy versus 6 (8.8%) control group (p = 0.29). Vitamin D insufficiency occurred in 30 (44.1%) children with epilepsy compared to 27(39.7%) control group. Children on ASMs had lower mean vitamin D levels than the control group (p = 0.02). Children on enzyme-inducing ASMs had lower mean vitamin D levels (p = 0.08), vitaminD2 (p = 0.0018), vitaminD3 (p = 0.004), serum phosphate levels (p = 0.000), and higher mean parathyroid hormone levels (p = 0.03) compared to controls. There was no difference in dietary intake and ancestry, although the dietary content of both groups was low in vitamin D products. CONCLUSIONS: Low vitamin D levels were common in children from both groups, but statistically lower for the children on ASMs. Children on enzyme-inducing ASMs need screening for vitamin D deficiency. The literature supports extending this for all children on ASMs. This is the first study to report that children on enzyme-inducing ASMs have lower levels of Vitamin D2 and D3 levels, probably as result of increased destruction of vitamin D. Improved vitamin D intake for children in vulnerable settings is important.

Potential protein-binding displacement interactions with perampanel: An in vitro analysis.

Plasma protein binding and effects on volume of distribution and pharmacologically active, circulating-drug concentrations are complex issues. Protein-binding displacement often underlies drug-drug interactions. Perampanel is a once-daily oral anti-seizure drug for focal seizures and primary generalized tonic-clonic seizures. Perampanel is also indicated for monotherapy use for focal seizures in the United States. Perampanel is extensively but slowly metabolized via CYP3A4. Its elimination t½ is about 100 h, and it displays substantial plasma protein binding (>95%). Here, we examine perampanel's potential to displace highly bound anti-seizure drugs and the ability of warfarin, a standard highly protein-bound drug, to displace perampanel. Protein binding of perampanel, phenytoin, valproate, and warfarin was assessed using equilibrium dialysis. Plasma samples containing each compound were dialyzed against phosphate buffered saline. For phenytoin, valproate, and warfarin, plasma samples were also dialyzed in the presence of perampanel. After 24 h equilibrium dialysis, amounts of test compounds were analyzed to calculate plasma protein binding. At clinically relevant concentrations, perampanel did not displace other highly bound drugs or vice versa. Protein-binding displacement may confound therapeutic drug monitoring of extensively protein-bound medications. Without empirical data, clinicians might be concerned that addition of perampanel could alter unbound concentrations of other medications, resulting in adverse effects. Our data indicate perampanel has low potential for drug interactions resulting from protein-binding displacement.