Objectives: This open-label follow-on trial aimed to investigate long-term safety and efficacy of lacosamide in patients with painful diabetic neuropathy.
Methods: After 1-week baseline period, lacosamide 100mg/day was started. Each week, based on pain and safety assessments, doses were escalated by 100mg/day to an optimal level, up to a maximum of 400mg/day. Patients then entered the 20-week maintenance period (dose adjusted as needed). Thereafter, patients could opt to continue lacosamide up to about 2.5 years (extension period).
Results: Of the 69 enrolled patients, 47 (68%) completed the 20-week maintenance period and elected to continue into the extension period; 37/69 (54%) patients were in the extension period for more than one year and 34/69 (49%) continued until study termination. The modal lacosamide dose in most patients (54%) was 400mg/day. Headache, upper respiratory tract infection, arthralgia, sinusitis, nasopharyngitis, and back pain were the most frequently reported adverse events (10% of patients). Significant reductions from baseline in Likert pain scores began during dose titration and were sustained throughout the study. Significant improvements were also seen in Neuropathic Pain Scale, Quality of Life scores, and Patient's Global Impression of Change assessment. Of 34 patients at study termination, 32 (90%) elected to continue with lacosamide treatment in another long-term open-label trial (NCT00235443).
Conclusion: The long-term safety profile and sustained efficacy of lacosamide observed in this trial support its continued development for treatment of painful diabetic neuropathy.