Effects of gabapentin, pregabalin and gastroretentive gabapentin on simulated driving, daytime sedation and cognition

Cognitive effect of antiseizure medications in medial temporal lobe epilepsy

BACKGROUND AND PURPOSE

The specific effects of antiseizure medications (ASMs) on cognition are a rich field of study, with many ongoing questions. The aim of this study was to evaluate these effects in a homogeneous group of patients with epilepsy to guide clinicians to choose the most appropriate medications.

METHODS

We retrospectively identified 287 refractory patients with medial temporal lobe epilepsy associated with hippocampal sclerosis. Scores measuring general cognition (global, verbal and performance IQ), working memory, episodic memory, executive functions, and language abilities were correlated with ASM type, number, dosage and generation (old vs. new). We also assessed non-modifiable factors affecting cognition, such as demographics and epilepsy-related factors.

RESULTS

Key parameters were total number of ASMs and specific medications, especially topiramate (TPM) and sodium valproate (VPA). Four cognitive profiles of the ASMs were identified: (i) drugs with an overall detrimental effect on cognition (TPM, VPA); (ii) drugs with negative effects on specific areas: verbal memory and language skills (carbamazepine), and language functions (zonisamide); (iii) drugs affecting a single function in a specific and limited area: visual denomination (oxcarbazepine, lacosamide); and (iv) drugs without documented cognitive side effects. Non-modifiable factors such as age at testing, age at seizure onset, and history of febrile seizures also influenced cognition and were notably influenced by total number of ASMs.

CONCLUSION

We conclude that ASMs significantly impact cognition. Key parameters were total number of ASMs and specific medications, especially TPM and VPA. These results should lead to a reduction in the number of drugs received and the avoidance of medications with unfavorable cognitive profiles.

Gabapentinoids for Pain: A Review of Published Comparative Effectiveness Trials and Data Submitted to the FDA for Approval

Use of the gabapentinoids for pain continues to increase. In 2018, the US Food and Drug Administration (FDA) strengthened the warnings for both gabapentin and pregabalin to emphasize the central nervous system side effects and the risk of respiratory depression, especially when combined with other centrally acting drugs. We reviewed the published comparative effectiveness literature for gabapentinoids for pain as well as all trials (published and unpublished) used by the FDA for the approval of the five pain indications for these agents (one for gabapentin, four for pregabalin). Among the findings of interest are the fact that the FDA rejected the application for gabapentin for diabetic peripheral neuropathy based on the risk versus benefit profile of that drug in the clinical trials that were submitted by the manufacturer. Additionally, both the comparative effectiveness trials as well as the studies used by the FDA tend to be short in duration and show only modest pain benefits for the gabapentinoids. The placebo response in these trials was frequently one-third to one-half as great as the pain benefit demonstrated by the gabapentinoid. Based on the available clinical trial evidence, we feel prescribers should be cautious when using gabapentinoids for pain, particularly when using these agents for a prolonged period or when combined with other, centrally acting agents.

Silexan does not affect driving performance after single and multiple dose applications: Results from a double-blind, placebo and reference-controlled study in healthy volunteers

Anxiolytic drugs often have sedative effects that impair the ability to drive. Our double-blind, randomized crossover trial investigated the effect of Silexan, a non-sedating, anxiolytic herbal medicinal product, on driving performance in healthy volunteers. Part 1 aimed at demonstrating equivalence between 80 mg/d Silexan and placebo. Part 2 was performed to demonstrate superiority of 160 and 320 mg Silexan over 1 mg lorazepam and included a placebo arm for assay sensitivity. Driving performance was assessed in a validated, alcohol-calibrated simulator test. The primary outcome was the standard deviation of the lane position (SDLP). Secondary outcomes included driving errors and sleepiness. Fifty and 25 subjects were randomized in Parts 1 and 2, respectively. In Part 1, Silexan 80 mg was confirmed to be equivalent to placebo after single administration (equivalence range: δ = ±2 cm). The 95% confidence interval (CI) for the SDLP marginal mean value difference Silexan-placebo for single administration was -1.43; +1.38 and thus similar to the 95% CI of -1.45; +0.79 cm for 7 days' multiple dosing. In Part 2, 95% CIs for SDLP marginal mean value differences to lorazepam were -8.58; -5.42 cm for Silexan 160 mg and -8.65; -5.45 cm for 320 mg (p < 0.001). Confirmatory results were supported by secondary outcomes, where results for Silexan were comparable to placebo and more favorable than for lorazepam. The study demonstrates that single doses of up to 320 mg Silexan and multiple doses of 80 mg/d have no adverse effect on driving performance.

Evaluation of the cognitive benefits of intrathecal baclofen pump implantation in people with intractable multiple sclerosis related spasticity

BACKGROUND

Spasticity is a common problematic symptom in Multiple Sclerosis with over one third of patients failing first line therapies. Intrathecal baclofen is a safe and efficacious option for treatment resistant spasticity. Anecdotally patients report improved concentration/cognitive performance when switching to intrathecal baclofen (ITB) from systemic medications.

AIM

To explore whether subjects who proceed with ITB pump implantation for spasticity management and reduce oral anti-spasticity agents will have improved cognitive function.

METHODS

Subjects were admitted for trial of ITB via lumbar puncture and subsequent pump implantation. Spasticity and cognitive measures before ITB trial and 3 months post implant were recorded. Paired t-test or Wilcoxon Signed Ranks test was used for within subject change and effect sizes (Cohen's d_z) were calculated. Subgroup analysis of those on ≥2, or ≤ 1 spasticity medications at baseline was performed.

RESULTS

27 subjects with MS completed per protocol. Mean age 46 years [26 - 56], disease duration 15 years [6 - 26], RRMS = 3, SPMS = 17 and PPMS=7. The majority were on multiple spasticity medications. Spasticity scores significantly improved post pump implant. Mean ITB dose at 3 months was 143 mcg / day and 19 discontinued all other treatments for spasticity. There was no deterioration on any cognitive or mood measure. An improvement of moderate effect size was found in Backwards Digit Span (d=0.41, p=0.059) and HADS - anxiety (d=0.37, p=0.097). Fatigue Severity Scale score decreased substantially (d=0.81, p=0.005). Small improvements in Symbol Digit Modalities Test score (d=0.24) and Sustained Attention to Response Task response time (d=0.23) were non-significant. Performance on other measures did not change. Effect sizes were larger in subgroup on ≥2 oral spasticity medications at baseline, compared to the group on ≤1 medication (SDMT, d=0.42 vs d=0.07; Backwards digit span 0.45 vs 0.28; HADS-anxiety 0.39 vs 0.32; HADS-depression d=0.32 vs 0.05 and FSS, d= 1.14 vs 0.42).

CONCLUSIONS

In a pilot study exploring the impact of ITB on cognition, spasticity scores improved universally and beneficial effects on some measures of fatigue, anxiety, auditory attention and verbal working memory were found. Improvement of speed of processing in those withdrawing higher doses of oral medication was also demonstrated suggesting that switching to ITB has added cognitive and psychological benefits for people with MS.