The long-term efficacy of cannabidiol in the treatment of refractory epilepsy.

OBJECTIVE: Cannabidiol (CBD) has been shown to reduce seizures among patients with refractory epilepsies of various etiologies in recent clinical trials and an expanded access program (EAP). Most studies report efficacy over short time periods (<1 year), with little published on longer term efficacy. Here, we investigate the efficacy of CBD for a treatment period of up to 60 months (median = 45.5 months). METHODS: We conducted a retrospective review of patient-reported seizure logs and medical records for 54 subjects with refractory epilepsy who enrolled in the Massachusetts General Hospital's open-label EAP for CBD as a new treatment for epilepsy. We analyzed the effect of CBD on seizure frequencies and concomitant antiepileptic drug (AED) use at 1 year after starting treatment and the most recent study visit. RESULTS: Our results indicate that CBD maintains its efficacy for controlling seizures from Year 1 to the most recent study visit. The percentage of seizure responders remained similar at these time points (41.7%-42.6%), and the seizure response rate was also maintained (p = .12). Efficacy was also seen over a broad dose range, and up to 50 mg/kg/day. CBD was particularly effective for controlling seizures in the setting of tuberous sclerosis complex and for reducing epileptic spasms and absence seizures. Although CBD use did not lead to an overall decrease in concomitant AEDs, most subjects reduced the dose of at least one concomitant AED compared to baseline. CBD was generally well tolerated, with drowsiness and diarrhea as the primary adverse reactions. SIGNIFICANCE: This study demonstrates CBD does not lose its efficacy in controlling seizures over a treatment period of up to 60 months. Taken alongside other results on the efficacy and tolerability of CBD in the treatment of refractory epilepsies, our results provide evidence that CBD is an effective, safe, and well-tolerated AED for long-term use.

Efficacy of cannabidiol in subjects with refractory epilepsy relative to concomitant use of clobazam.

OBJECTIVE: To evaluate the efficacy of open-label, highly purified cannabidiol (CBD, Epidiolex®) in treating refractory epilepsy relative to the concomitant use of clobazam (CLB) as well as the clinical implications of changes in CLB and norclobazam (nCLB) levels. METHODS: Data were examined retrospectively, in patients who either used CBD with concomitant CLB or without concomitant CLB after two months of treatment with CBD and at the point of best seizure control within the first year of treatment with CBD. Responder rates (percentage of subjects with a 50 % or greater reduction in weekly seizures from their baseline) and mean reduction in weekly seizure frequency were calculated and compared between those who concomitantly used CLB and those who did not. The relationship between the change in CLB and nCLB levels and change in mean weekly seizure frequency was also investigated within the group of subjects using concomitant CLB and CBD. RESULTS: We analyzed data from 47 subjects between the ages of 2.5-51 years. There was no significant difference between the concomitant CLB (n = 32) and no concomitant CLB (n = 15) groups in terms of demographics (age (p = 0.4344), race (p = 1.0000), sex (p = 0.7507)) or most epilepsy characteristics (underlying condition (all p > 0.05), mean baseline seizure frequency (p = 0.6483)). There was only one significant difference between groups regarding seizure types (more subjects with epileptic spasms in concomitant CLB group (p = 0.0413)). Concomitant AED usage was not significantly different in the two groups (all p > 0.05). Mean reduction in weekly seizure frequency was greater at the best point of seizure control within the first year than at two months of treatment with CBD, regardless of concomitant CLB usage (all p > 0.05). There was no significant difference in reduction of mean weekly seizure frequency between those who took concomitant CLB and those who did not at either time point (all p > 0.05). There was a significantly greater responder rate for subjects taking CBD and CLB than those taking CBD without CLB only at the point of best seizure control within the first year of CBD treatment (p = 0.0240). There was no strong, significant correlation between change in nCLB or CLB levels and change in seizure frequency at either time point (all |p|<0.22). SIGNIFICANCE: With or without concomitant CLB, CBD can be effective in reducing seizure frequency. Changes in nCLB and CLB levels do not have a clinically significant correlation with changes in weekly seizure frequency for those taking CBD with CLB.

Cannabidiol as a new treatment for drug-resistant epilepsy in tuberous sclerosis complex.

OBJECTIVE: Tuberous sclerosis complex (TSC) is an autosomal-dominant genetic disorder with highly variable expression. The most common neurologic manifestation of TSC is epilepsy, which affects approximately 85% of patients, 63% of whom develop treatment-resistant epilepsy. Herein, we evaluate the efficacy, safety, and tolerability of cannabidiol (CBD), a nonpsychoactive compound derived from the marijuana plant, as an adjunct to current antiepileptic drugs in patients with refractory seizures in the setting of TSC. METHODS: Eighteen of the 56 patients who have enrolled in our current expanded-access study of cannabidiol for patients with treatment-resistant epilepsy carry a diagnosis of TSC. After an initial baseline period of 1 month, patients began treatment with CBD. The initial dose of 5 mg/kg/day was increased by 5 mg/kg/day every week up to a maximum dose of 50 mg/kg/day, if tolerated. Weekly seizure frequencies, percent change in seizure frequencies, and responder rates were calculated during the 2nd, 3rd, 6th, 9th, and 12th month of treatment with CBD. RESULTS: The median weekly seizure frequency during the baseline period was 22.0 (interquartile range [IQR] 14.8-57.4), which decreased to 13.3 (IQR 5.1-22.1) after 3 months of treatment with cannabidiol. The median percent change in total weekly seizure frequency was -48.8% (IQR -69.1% to -11.1%) after 3 months of treatment. The 50% responder rates over the course of the study were 50%, 50%, 38.9%, 50%, and 50% after 2, 3, 6, 9, and 12 months of treatment with CBD, respectively. In patients taking clobazam concurrently with CBD (n = 12), the responder rate after 3 months of treatment was 58.3%, compared to 33.3% in patients not taking clobazam (n = 6). Twelve (66.7%) of 18 patients in this study experienced at least one adverse event thought possibly related to CBD; the most common adverse events were drowsiness (n = 8, 44.4%), ataxia (n = 5, 27.8%), and diarrhea (n = 4, 22.2%). SIGNIFICANCE: Although double-blind, placebo-controlled trials are still necessary, these findings suggest that cannabidiol may be an effective and well-tolerated treatment option for patients with refractory seizures in TSC.