Pharmacology and clinical efficacy of dalfampridine for treating multiple sclerosis

Altered Expression of Ion Channels in White Matter Lesions of Progressive Multiple Sclerosis: What Do We Know About Their Function?

Despite significant advances in our understanding of the pathophysiology of multiple sclerosis (MS), knowledge about contribution of individual ion channels to axonal impairment and remyelination failure in progressive MS remains incomplete. Ion channel families play a fundamental role in maintaining white matter (WM) integrity and in regulating WM activities in axons, interstitial neurons, glia, and vascular cells. Recently, transcriptomic studies have considerably increased insight into the gene expression changes that occur in diverse WM lesions and the gene expression fingerprint of specific WM cells associated with secondary progressive MS. Here, we review the ion channel genes encoding K⁺, Ca²⁺, Na⁺, and Cl^- channels; ryanodine receptors; TRP channels; and others that are significantly and uniquely dysregulated in active, chronic active, inactive, remyelinating WM lesions, and normal-appearing WM of secondary progressive MS brain, based on recently published bulk and single-nuclei RNA-sequencing datasets. We discuss the current state of knowledge about the corresponding ion channels and their implication in the MS brain or in experimental models of MS. This comprehensive review suggests that the intense upregulation of voltage-gated Na⁺ channel genes in WM lesions with ongoing tissue damage may reflect the imbalance of Na⁺ homeostasis that is observed in progressive MS brain, while the upregulation of a large number of voltage-gated K⁺ channel genes may be linked to a protective response to limit neuronal excitability. In addition, the altered chloride homeostasis, revealed by the significant downregulation of voltage-gated Cl^- channels in MS lesions, may contribute to an altered inhibitory neurotransmission and increased excitability.

HPLC method development for fampridine using Analytical Quality by Design approach

Offering a systematic and multivariate analysis of the analytical procedure, development and validation of HPLC methods using Quality by Design approach are in the limelight of current research trends. A new, experimental design-aided HPLC method for fampridine was developed and preliminarily validated according to current in-force international guidelines for linearity, accuracy, robustness and precision. The method offers a high throughput sample analysis, with an elution time of 2.9 minutes, and signal detection without excipient interference performed at 262 nm. The method proved to be linear between 1-15 µg mL-1 (R2= 0.9996). The mean recovery was found to be 98.7 ± 1.9 % in the tested range of 2.5-7.5 µg mL-1. Low RSD values (< 1 %) were obtained for both model, intra- and inter-day precision. The limit of detection and limit of quantification were 0.24 and 0.78 µg mL-1, resp. The method proved to be applicable for active substance assay in a pharmaceutical dosage form.

Study on Dalfampridine in the treatment of Multiple Sclerosis Mobility Disability: A meta-analysis

Objective

Systematic Review was used to evaluate the efficacy and safety of Dalfampridine (DAP) in the treatment of Mobility Disability (MS) in patients with Multiple Sclerosis.

Methods

Clinical randomized controlled studies about DAP and placebo in the treatment of Mobility Disability in patients with Multiple Sclerosis until March 2019 were explored by searching Embase, PubMed, Cochrane, Web of Knowledge, and ClinicalTrials.gov. Literature screening, data extraction, quality assessment, and statistical analysis were performed by using Stata 14.0.

Results

10 papers were included in the meta-analysis, and the number of patients was 2100. In conclusion, the application of DAP in clinical can significantly improve the Mobility Disability of patients [OR = 2.73, 95%CI (1.66, 4.50), P<0.001, I² = 74.1%] and boost the mobility speed of patients in Timing 24 Minute Walk Test (T24FW) [SMD = 3,08, 95%CI(1,58, 4.58), P<0.001, I² = 98.7%]. There are no significant differences of the incidence of adverse events [RR = 1.06, 95%CI (0.99, 1.14), P = 0.928, I² = 0.0%] and urinary tract infection [RR = 1.21, 95%CI(0.91, 1.60), P = 0.145, I² = 37.2%] between the DAP test group (Doses≤10 mg) and the placebo control group, and the incidence of adverse events [RR = 1.14, 95%CI(1.02, 1.28), P = 0.793, I² = 0.0%] and urinary tract infection[RR = 3.05, 95%CI(1.04, 8.99), P = 0.680, I² = 0.0%] for the DAP test group (Doses>10 mg) is a litter higher than the placebo control group.

Conclusion

DAP can effectively improve Mobility Disability in patients with Multiple Sclerosis, which is safe and reliable in specific DAP usage doses.

Evaluating dalfampridine for the treatment of relapsing-remitting multiple sclerosis: does it add to the treatment armamentarium?

Introduction: Multiple sclerosis (MS) is a demyelinating disease, causing axonal damage and disability. Dalfampridine (DAL) is an extended-release formulation of 4-aminopyridine (4AP) and broad-spectrum voltage-dependent potassium channel blocker that is reported to improve motor, visual and cognitive functions. Furthermore, it is presently the only approved drug for walking impairment in MS. Areas covered: Herein, the authors evaluate DAL as a relapsing-remitting MS treatment, reporting and commenting on all aspects of the drug including its chemistry, safety, pharmacokinetics, and cost-effectiveness. A bibliographic search was performed on PubMed using the terms 'dalfampridine OR fampridine OR 4-aminopyridine'. Expert opinion: Evidence from post-marketing studies suggests that DAL, consistent with the effects of 4AP, may not only improve walking speed, but also arm function, fatigue, mood and cognition through restored nerve conduction in central nervous system demyelinated areas. Long-term safety data confirm that the approved dose of 10 mg twice daily is generally well tolerated. However, despite the reported efficacy, the extent of the benefits is limited in real life activities, although significant improvements have been demonstrated in the clinical setting. Patients often complain of side effects (such as cramps and painful paraesthesia) or lack of efficacy. Also, its considerably higher pricing in comparison to 4AP represents an important limitation.

Effects of 4-aminopyridine on attention and executive functions of patients with multiple sclerosis: Randomized, double-blind, placebo-controlled clinical trial. Preliminary report

BACKGROUND

A high percentage of patients with multiple sclerosis present cognitive alterations. Because 4-aminopyridine improves nerve conduction and efficient synaptic connection could improve cognitive dysfunction.

OBJECTIVE

To evaluate the efficacy on cognitive performance and safety of 4-aminopyridine administered to patients with relapsing-remitting multiple sclerosis.

METHODS

A randomized, double-blind, placebo controlled clinical trial was conducted in patients with relapsing-remitting multiple sclerosis diagnosis according to the McDonald criteria. At the beginning and at the end of the treatment different tests were used to assess cognitive performance. Subsequently, patients were randomized 1:1 to receive treatment or placebo. A bootstrap-t test was proposed to test the effectiveness of cognitive performance, considering a p-value < 0.05 as statistically significant.

RESULTS

Twenty-four patients were recruited of which 21 completed the trial, 11 with 4-aminopyridine and 10 with placebo treatment. No significant differences between groups in the initial assessments were observed. In terms of efficacy, the experimental group achieved significantly higher scores in attention span, verbal fluency, planning and graphics and constructive motion.

CONCLUSIONS

4-aminopyridine proved to be an effective treatment on cognitive aspects in patients with relapsing-remitting multiple sclerosis. Drug doses were shown to be safe with mild to moderate adverse events (ClinicalTrials.gov number, NCT02280096).

Pharmacogenetics of Potassium Channel Blockers

The QT interval on surface electrocardiograms provides a model of a multicomponent integrated readout of many biological systems, including ion channels, modulatory subunits, signaling systems that modulate their activity, and mechanisms that regulate the expression of their responsible genes. The problem of drug exposure causing exaggerated QT interval prolongation and torsades de pointes highlights the multicomponent nature of cardiac repolarization and the way in which simple perturbations can yield exaggerated responses. Future directions will involve cellular approaches coupled to evolving technologies that can interrogate multicellular systems and provide a sophisticated view of mechanisms in this previously idiosyncratic drug reaction.