Dalfampridine: A Medication to Improve Walking in Patients with Multiple Sclerosis

Post-marketing safety surveillance of dalfampridine for multiple sclerosis using FDA adverse event reporting system

Objective: To investigate and analyze the post-marketing adverse event (AE) data of multiple sclerosis (MS) therapeutic drug dalfampridine using the US Food and Drug Administration Adverse Event Reporting System (FAERS) for its clinical safety application. Methods: Use OpenVigil2.1 platform to obtain AE data of dalfampridine from FAERS from February 2010 to September 2022. Match "adverse drug reaction" with preferred term (PT) and system organ class (SOC) according to the Medical Dictionary for Regulatory Activities (MedDRA), then merge the same PT and delete non-AE PT. Positive signals were identified by the reporting odds ratio (ROR), proportional reporting ratio (PRR), and Bayesian confidence propagation neural network (BCPNN) methods. When AE signals met the criteria of those three methods, they were identified as positive signals. Results: A total of 44,092 dalfampridine-related AE reports were obtained, and 335 AE signals were identified, including 11,889 AE reports. AEs were more common in females and in the 45-65 age group, which is consistent with the epidemiological characteristics of MS. The 335 AE signals involved 21 SOCs, including investigations, infections and infestations, eye disorders, etc. Among the top 20 PTs in signal strength, 10 were associated with abnormal lymphocyte percentage and count, and 5 were associated with abnormal urine tests, some of which were not described in the instruction, such as spinal cord injury cauda equina, haemoglobin urine present, urinary sediment abnormal and so on. The most frequently reported AE signals were urinary tract infection, dizziness, condition aggravated. In addition, 23 AE signals with death outcomes were identified, with an incidence of less than 0.1%. Conclusion: Data mining of FAERS was conducted to analyze the AEs of dalfampridine, and new AE signals were found. This study provides a reference for the safe use of dalfampridine in the treatment of MS.

Dalfampridine in the treatment of multiple sclerosis: a meta-analysis of randomised controlled trials

Background

Multiple sclerosis (MS) is a chronic illness involving the central nervous system (CNS) that is characterised by inflammation, demyelination, and degenerative changes. Dalfampridine is one of the available treatments for MS symptoms and comorbidities. This meta-analysis aimed to assess the safety and benefits of dalfampridine versus placebo in MS by summarising data deriving from previously published clinical randomised controlled studies (RCTs).

Results

A total of 9 RCTs were included in this meta-analysis, involving 1691 participants. There were significant differences between dalfampridine and placebo in terms of decreased 12-item Multiple Sclerosis Walking Scale score (weighted mean difference [WMD] =  − 3.68, 95% confidence interval [CI] [− 5.55, − 1.80], p = 0.0001), improved response to the timed 25-foot walk test (relative risk [RR] = 2.57, 95% CI [1.04, 6.33], p = 0.04), increased 6-min walk test (WMD = 18.40, 95% CI [1.30, 35.51], p = 0.03), increased 9-Hole Peg Test score (WMD = 1.33, 95% CI [0.60, 2.05], p = 0.0004), and increased Symbol Digit Modalities Test score (WMD = 4.47, 95% CI [3.91, 5.02], p < 0.00001). Significant differences in the incidence of side effects were also observed (RR = 1.12, 95% CI [1.04, 1.21], p = 0.002).

Conclusion

Dalfampridine exerts positive effects on walking ability, finger dexterity, and cognitive function. Treatment should be administered under the guidance of a physician or pharmacist given the higher incidence of adverse events.

Cortical Excitability Measures May Predict Clinical Response to Fampridine in Patients with Multiple Sclerosis and Gait Impairment

Background: Most multiple sclerosis (MS) patients will develop walking limitations during the disease. Sustained-release oral fampridine is the only approved drug that will improve gait in a subset of MS patients. Objectives: (1) Evaluate fampridine cortical excitability effect in MS patients with gait disability. (2) Investigate whether cortical excitability changes can predict the therapeutic response to fampridine. Method: This prospective observational study enrolled 20 adult patients with MS and gait impairment planned to receive fampridine 10 mg twice daily for two consecutive weeks. Exclusion criteria included: Recent relapse (<3 months), modification of disease modifying drugs (<6 months), or Expanded Disability Status Scale (EDSS) score >7. Neurological examination, timed 25-foot walk test (T25wt), EDSS, and cortical excitability studies were performed upon inclusion and 14 days after initiation of fampridine. Results: After treatment, the mean improvement of T25wt (ΔT25wt) was 4.9 s. Significant enhancement of intra-cortical facilitation was observed (139% versus 241%, p = 0.01) following treatment. A positive correlation was found between baseline resting motor threshold (rMT) and both EDSS (r = 0.57; p < 0.01) and ΔT25wt (r = 0.57, p = 0.01). rMT above 52% of the maximal stimulator output was found to be a good predictor of a favorable response to fampridine (accuracy: 75%). Discussion: Fampridine was found to have a significant modulatory effect on the cerebral cortex, demonstrated by an increase in excitatory intracortical processes as unveiled by paired-pulse transcranial magnetic stimulation. rMT could be useful in selecting patients likely to experience a favorable response to fampridine.

Feasibility of Restoring Walking in Multiple Sclerosis with Multichannel Implanted Electrical Stimulation

A patient with multiple sclerosis-related gait dysfunction was followed over the course of his disease. Despite aggressive treatment, he developed significant weakness in ankle dorsiflexors and hip and knee flexors and was no longer capable of consistently taking a step on his own. With electrical stimulation of hip and knee flexors and ankle dorsiflexors using implanted electrodes, he was able to consistently walk short distances as far as 30 m, thus significantly improving his Expanded Disability Status Scale score. This case study supports further exploration into the potential benefits of an implanted pulse generator to ameliorate gait dysfunction and improve quality of life for people with multiple sclerosis.

Multiple sclerosis and the blood-central nervous system barrier

The central nervous system (CNS) is isolated from the blood system by a physical barrier that contains efflux transporters and catabolic enzymes. This blood-CNS barrier (BCNSB) plays a pivotal role in the pathophysiology of multiple sclerosis (MS). It binds and anchors activated leukocytes to permit their movement across the BCNSB and into the CNS. Once there, these immune cells target particular self-epitopes and initiate a cascade of neuroinflammation, which leads to the breakdown of the BCNSB and the formation of perivascular plaques, one of the hallmarks of MS. Immunomodulatory drugs for MS are either biologics or small molecules, with only the latter having the capacity to cross the BCNSB and thus have a propensity to cause CNS side effects. However, BCNSB penetration is a desirable feature of MS drugs that have molecular targets within the CNS. These are nabiximols and dalfampridine, which target cannabinoid receptors and potassium channels, respectively. Vascular cell adhesion molecule-1, present on endothelial cells of the BCNSB, also serves as a drug discovery target since it interacts with α4-β1-integrin on leucocytes. The MS drug natalizumab, a humanized monoclonal antibody against α4-β1-integrin, blocks this interaction and thus reduces the movement of immune cells into the CNS. This paper further elaborates on the role of the BCNSB in the pathophysiology and pharmacotherapy of MS.

Clinical overview of dalfampridine: an agent with a novel mechanism of action to help with gait disturbances

BACKGROUND

Medication used to treat multiple sclerosis (MS) can be categorized as disease-modifying therapies, symptomatic therapies, or treatment of acute exacerbations. Dalfampridine is the first symptomatic therapy approved by the Food and Drug Administration to improve walking in patients with MS.

OBJECTIVE

This article reviews the pharmacology, pharmacodynamic properties, and pharmacokinetic properties of dalfampridine, as well as its clinical efficacy, safety profile, pharmacoeconomic considerations, and place in therapy.

METHODS

Three PubMed searches were conducted for original articles published in English between 1966 and August 2012 with human study participants. Articles concerning the pharmacology, pharmacokinetic properties, pharmacodynamic properties, efficacy, and safety profile of dalfampridine were evaluated.

RESULTS

Dalfampridine theoretically works to improve conduction and enhance walking by inhibiting potassium channels in the axonal membrane and by prolonging action potentials in demyelinated neurons. The efficacy of dalfampridine has been reported in 2 Phase III clinical trials in patients with MS. When comparing dalfampridine 10 mg twice daily with placebo, these studies found a statistically significant improvement in walking (42.9% vs 9.3% and 35% vs 8%; P < 0.001). However, clinical trials and postmarketing surveillance have shown an increased risk of seizures with dalfampridine use that appears to be dose related [corrected].

CONCLUSIONS

Dalfampridine has a unique mechanism of action, leading to its approval as the first symptomatic therapy for MS to improve walking speed. The increased risk of seizures can be a safety concern and will require health care providers to be diligent in monitoring patients and to ensure adequate patient education [corrected]. The addition of dalfampridine as symptomatic therapy for MS may lead to additional novel products in the future.