title: Safety profile of dalfampridine extended release in multiple sclerosis: 5-year postmarketing experience in the United States.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Acorda Therapeutics, Inc., Ardsley, NY, USA.
authors.forename: Michele
authors.initials: M
authors.lastname: Jara
authors.affiliation: Acorda Therapeutics, Inc., Ardsley, NY, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Aquilina
authors.affiliation: Acorda Therapeutics, Inc., Ardsley, NY, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Aupperle
authors.affiliation: Acorda Therapeutics, Inc., Ardsley, NY, USA.
authors.forename: Adrian L
authors.initials: AL
authors.lastname: Rabinowicz
keywords: adverse events; dalfampridine; fampridine; multiple sclerosis; postmarketing safety