Study design:Two randomized, double-blind, placebo-controlled trials.Objective:To evaluate the efficacy and safety of fampridine sustained-release tablets (fampridine-SR) 25 mg twice daily for moderate-to-severe spasticity in patients with chronic spinal cord injury (SCI).Setting:United States and Canada.Methods:Patients with incomplete chronic SCI were randomized to twice daily fampridine-SR 25 mg or placebo, with a 2-week single-blind placebo run-in, a 2-week titration, 12 weeks of stable dosing, 2 weeks of downward titration and 2 weeks of untreated follow-up. Co-primary end points were the change from baseline, averaged over the double-blind treatment period, for Ashworth score (bilateral knee flexors and extensors) and a 7-point Subject Global Impression of treatment (SGI; 1, terrible; 7, delighted). Secondary end points were: Penn Spasm Frequency Scale; the motor/sensory score from the International Standards for Neurological Classification of SCI; Clinician's Global Impression of Change of neurological status; and the International Index of Erectile Function (men) or the Female Sexual Function Index (women).Results:The populations were 212 and 203 patients in the two studies, respectively. Changes from baseline in Ashworth score were -0.15 (placebo) and -0.19 (fampridine-SR) in the first study, and -0.16 (placebo) and -0.28 (fampridine-SR) in the second study. The between-treatment difference was not significant for either the Ashworth score or the SGI and, with few exceptions, neither were the secondary end points. Fampridine-SR was generally well tolerated; treatment-emergent adverse events (TEAEs) and serious TEAEs were reported with similar frequency between treatments.Conclusion:Fampridine-SR was well tolerated. No significant differences were observed between treatment groups for the primary end points of Ashworth score and SGI. © 2014 International Spinal Cord Society All rights reserved.