Temporal analysis of pain responders and common adverse events: when do these first appear following treatment with pregabalin

BACKGROUND: Pregabalin is an α(2)δ ligand indicated in the USA for treatment of a number of chronic pain conditions, including diabetic peripheral neuropathy, postherpetic neuralgia, pain associated with spinal cord injury, and fibromyalgia. A greater understanding of when patients first respond to treatment with pregabalin and when adverse events emerge, or worsen, could aid design of new proof-of-concept studies and help guide treatment of patients. METHODS: This was an analysis of five randomized, placebo-controlled, double-blind trials (between 8 and 16 weeks in duration) of flexible-dose pregabalin (150–600 mg/day). Individual patient data were pooled into three groups by disease condition: diabetic peripheral neuropathy or postherpetic neuralgia (n=514), spinal cord injury (n=356), and fibromyalgia (n=498). Responders were classified as having a ≥30% and/or ≥50% reduction in mean pain score from baseline; once a patient responded, they were not scored subsequently (and were excluded from the responder analysis). The emergence of adverse events at each week was also recorded. RESULTS: The majority of the 30% and 50% responders emerged within the first 3–4 weeks with pregabalin, but were more uniformly distributed across the 6 weeks of the analysis with placebo. The majority of common adverse events also emerged within the first 3–4 weeks of pregabalin treatment. CONCLUSION: These data suggest that the majority of pain responders and common adverse events emerge within 3–4 weeks of treatment with pregabalin. These data could advise new proof-of-concept studies and guide clinical management.