Dalfampridine extended release tablets: 1 year of postmarketing safety experience in the US

Efficacy and safety of fampridine for walking disability in multiple sclerosis

Fampridine is the only drug approved for the treatment of walking impairment in multiple sclerosis. Around a third of the patients on treatment obtained an improvement in walking speed during the development phase. The effects are clinically significant, appear soon after the start of the treatment and are long-lasting, but disappear soon after the drug is withdrawn. In the real-world setting, the number of patients with a significant response to the treatment seems to be higher (around 70%). The tolerance is good, with mild to moderate, and transient adverse events. The most commonly reported are insomnia, headache, fatigue, back pain, dizziness, nausea and balance disorders. The main contraindications are a history of seizures, renal impairment and concomitant treatment with OCT2 inhibitors.

The potassium channel blocker, dalfampridine diminishes ouabain-induced arrhythmia in isolated rat atria

The aim of the present experiment was to investigate the possible antiarrhythmic effects of dalfampridine in ouabain-induced arrhythmia in rats. Twenty-four male rats including the control and dalfampridine-incubated (100 µM to 10 mM) ouabain-stimulated (40 µM) groups were used. After induction of anesthesia, the atria were isolated and the time of onset of arrhythmia and asystole were recorded. The contractile force of atria was also measured. Dalfampridine at concentration of 1 mM significantly postponed the onset of arrhythmia and asystole compared to control group (p ≤ .05). Ouabain significantly increased the atrial beating rate in control group (p ≤ .05), while pretreatment of isolated atria with dalfampridine reversed this effect. Incubation of isolated atria with ouabain did not alter the contractile force in both control- and dalfampridine-treated groups (p > .05). It is concluded that dalfampridine might possess antiarrhythmic properties in reducing the atrial arrhythmias.

Monitoring long-term efficacy of fampridine in gait-impaired patients with multiple sclerosis

Objective:

To expand upon the limited knowledge of the long-term effects of prolonged-release (PR) fampridine in patients with multiple sclerosis (PwMS) regarding safety, walking improvements, and changes in drug responsiveness.

Methods:

Fifty-three PwMS who completed the FAMPKIN core study were included in this extension trial. Drug efficacy was assessed in an open-label and randomized double-blind, placebo-controlled study design with regular baseline assessments over a period of 2 years using the Timed 25-Foot Walk (T25FW), 6-Minute Walk Test (6MWT), and 12-item MS Walking Scale (MSWS-12) as outcome measures.

Results:

The data showed good tolerability and persisting efficacy of PR fampridine during long-term treatment in PwMS. Significant improvements in walking speed, endurance, and self-perceived ambulatory function were observed during open-label (T25FW: +11.5%; 6MWT: 10.7%; MSWS-12: 6.1 points) and double-blind controlled treatment with PR fampridine (T25FW: +13.1%; 6MWT: 11.9%; MSWS-12: 7.4 points). Several patients showed changes in drug responsiveness over time, resulting in an increased proportion of patients exceeding 10% or 20% improvements in walking measures after long-term treatment.

Conclusions:

Efficacy and tolerability data confirmed PR fampridine as a valuable long-term treatment for improving ambulatory function in gait-impaired PwMS. Similar results in open-label and double-blind phases reveal that the walking tests used are objective and reliable. The considerable proportion of patients in whom responsiveness to PR fampridine changed over time emphasizes the importance of regular reassessment of drug efficacy in clinical practice to optimize treatment. Such reassessments seem to be particularly important in patients with poor initial drug responses, as this group demonstrated enhanced responsiveness after long-term treatment.

Clinicaltrials.gov identifier:

NCT01576354.

Classification of evidence:

This study provides Class II evidence that PR fampridine significantly improved gait compared to placebo in a 2-week study in PwMS who had been using PR fampridine for 2 years.

A guide to treating gait impairment with prolonged-release fampridine (Fampyra®) in patients with multiple sclerosis

INTRODUCTION

Gait impairment, a frequent sign in multiple sclerosis (MS), places a major burden on patients since it results in progressive loss of personal and social autonomy, along with work productivity. This guide aims to provide recommendations on how to evaluate gait impairment and use prolonged-release fampridine (PR-fampridine) as treatment for MS patients with gait impairment in Spain.

DEVELOPMENT

PR-fampridine dosed at 10mg every 12hours is currently the only drug approved to treat gait impairment in adults with MS. Additionally, PR-fampridine has been shown in clinical practice to significantly improve quality of life (QoL) in patients who respond to treatment. Treatment response can be assessed with the Timed 25-Foot Walk (T25FW) or the 12-item MS Walking Scale (MSWS-12); tests should be completed before and after starting treatment. The minimum time recommended for evaluating treatment response is 2 weeks after treatment onset. Patients are considered responders and permitted to continue the treatment when they demonstrate a decrease in their T25FW time or an increase in MSWS-12 scores. A re-evaluation is recommended at least every 6 months. The SF-36 (Short Form-36) and the MSIS-29 (MS Impact Scale-29) tests are recommended for clinicians interested in performing a detailed QoL assessment. This drug is generally well-tolerated and has a good safety profile. It should be taken on an empty stomach and renal function must be monitored regularly.

CONCLUSIONS

These recommendations will help ensure safer and more efficient prescription practices and easier management of PR-fampridine as treatment for gait impairment in Spanish adults with MS.

Safety profile of dalfampridine extended release in multiple sclerosis: 5-year postmarketing experience in the United States

BACKGROUND

Dalfampridine extended release tablets (dalfampridine-ER; prolonged-, modified, or sustained-release fampridine outside the US), 10 mg twice daily, was approved by the US Food and Drug Administration (FDA) in January 2010 to improve walking in people with multiple sclerosis, as determined by an increase in walking speed.

OBJECTIVE

To provide a descriptive analysis of reported adverse events (AEs) for commercially available dalfampridine-ER from March 2010 through March 31, 2015.

METHODS

Five-year postmarketing data for dalfampridine-ER were available from the exposure of approximately 107,000 patients in the US (103,700 patient-years). Commonly reported AEs (≥2% of all reported AEs) and serious AEs were determined. The incidence of reported seizures was determined and the events were further investigated.

RESULTS

Among the 107,000 patients exposed to dalfampridine-ER (70% female; mean age 52.1), the most common AEs were dizziness (3.7%), insomnia (3.2%), balance disorder (3%), fall (2.4%), headache (2.4%), nausea (2.1%), and urinary tract infection (2%). Other common AEs were drug ineffectiveness (5.8%), gait disturbance (4.6%), and inappropriate dosing (3.1%). Serious AEs included rare anaphylactic reactions (five cases) and drug hypersensitivity reactions (eight cases). A total of 657 seizure cases were reported (6.3/1,000 patient-years); of these, 324 were medically confirmed (3.1/1,000 patient-years). Incidence of reported seizures was stable over time. Duration of treatment prior to a seizure ranged from a single dose to >4 years; 12% of the seizures occurred within a week of starting treatment.

CONCLUSION

The 5-year US postmarketing safety data of dalfampridine-ER is consistent with the safety profile observed in clinical trials. Incidence of reported seizures remained stable over time. Since commercial availability in March 2010, a warning regarding the risk of anaphylaxis and severe allergic reactions was added to the US prescribing information.

Evaluation of Dalfampridine Extended Release 5 and 10 mg in Multiple Sclerosis: A Randomized Controlled Trial

BACKGROUND

Dalfampridine extended-release (ER) tablets, 10 mg twice daily, have been shown to improve walking in people with multiple sclerosis. We evaluated the safety and efficacy of dalfampridine-ER 5 mg compared with 10 mg.

METHODS

Patients were randomized to double-blind treatment with twice-daily dalfampridine-ER tablets, 5 mg (n = 144) or 10 mg (n = 143), or placebo (n = 143) for 4 weeks. Primary efficacy endpoint was change from baseline walking speed by the Timed 25-Foot Walk 3 to 4 hours after the last dose. At 40% of sites, 2-week change from baseline walking distance was measured by the 6-Minute Walk test.

RESULTS

At 4 weeks, walking speed changes from baseline were 0.363, 0.423, and 0.478 ft/s (placebo, dalfampridine-ER 5 mg, and dalfampridine-ER 10 mg, respectively [P = NS]). Post hoc analysis of average changes between pretreatment and on-treatment showed that relative to placebo, only dalfampridine-ER 10 mg demonstrated a significant increase in walking speed (mean ± SE): 0.443 ± 0.042 ft/s versus 0.303 ± 0.038 ft/s (P = .014). Improvement in 6-Minute Walk distance was significantly greater with dalfampridine-ER 10 mg (128.6 ft, P = .014) but not with 5 mg (76.8 ft, P = .308) relative to placebo (41.7 ft). Adverse events were consistent with previous studies. No seizures were reported.

CONCLUSIONS

Dalfampridine-ER 5 and 10 mg twice daily did not demonstrate efficacy on the planned endpoint. Post hoc analyses demonstrated significant increases in walking speed relative to placebo with dalfampridine-ER 10 mg. No new safety signals were observed.

Prolonged-release fampridine and walking and balance in MS: randomised controlled MOBILE trial

Background:

Mobility impairment is a common disability in MS and negatively impacts patients’ lives.

Objective:

Evaluate the effect of prolonged-release (PR) fampridine (extended-release dalfampridine in the United States) on self-assessed walking disability, dynamic/static balance and safety in patients with MS.

Methods:

MOBILE was a randomised, double-blind, exploratory, placebo-controlled trial. Patients with progressive/relapsing-remitting MS and Expanded Disability Status Scale score of 4.0–7.0 were treated with PR-fampridine or placebo twice daily for 24 weeks. Efficacy endpoints included change from baseline in the 12-item MS Walking Scale (MSWS-12), Timed Up and Go (TUG) test and Berg Balance Scale (BBS).

Results:

132 patients were randomised at 24 sites in six countries. PR-fampridine therapy resulted in greater median improvements from baseline in MSWS-12 score, TUG speed and BBS total score versus placebo over 24 weeks. A higher proportion of patients receiving PR-fampridine versus placebo experienced significant improvements at MSWS-12 improvement thresholds ⩾7 (p = 0.0275), ⩾8 (p = 0.0153) and ⩾9 points (p = 0.0088) and TUG speed thresholds ⩾10% (p = 0.0021) and ⩾15% (p = 0.0262). PR-fampridine was well tolerated.

Conclusions:

PR-fampridine therapy resulted in early and sustained improvements in broad measures of walking and balance over six months.

Development of dalfampridine, a novel pharmacologic approach for treating walking impairment in multiple sclerosis

Walking impairment is a clinical hallmark of multiple sclerosis (MS). Dalfampridine-ER, an extended-release formulation of dalfampridine (also known by its chemical name, 4-aminopyridine, and its international nonproprietary name, fampridine), was developed to maintain drug plasma levels within a narrow therapeutic window, and assessed for its ability to improve walking in MS. The putative mechanism of action of dalfampridine-ER is restoration of axonal conduction via blockade of the potassium channels that become exposed during axonal demyelination. Two pivotal phase III clinical trials demonstrated that dalfampridine-ER 10-mg tablets administered twice daily improved walking speed and patient-reported perceptions of walking in some patients. Dalfampridine-ER was generally well tolerated, and, at the approved dose, risk of seizure was neither elevated relative to placebo nor higher than the rate in the MS population. Dalfampridine-ER (AMPYRA®) was approved in the United States for the treatment of walking in patients with MS as demonstrated by an increase in walking speed. The use of the dalfampridine-ER is contraindicated in patients with a history of seizure. It is the first pharmacologic therapy for this indication and has been incorporated into clinical management of MS.