Effect of Concomitant Pain Medications on Response to Pregabalin in Patients with Postherpetic Neuralgia or Spinal Cord Injury-Related Neuropathic Pain.

BACKGROUND Patients with neuropathic pain (NeP) often receive combination therapy with multiple agents in the hopes of improving both pain and any comorbidities that may be present. While pregabalin is often recommended as a first-line treatment of NeP, few studies have examined the effects of concomitant medications on the efficacy of pregabalin. OBJECTIVE To examine the effects of concomitant medications on the efficacy and safety of pregabalin for the treatment of NeP. STUDY DESIGN Data were derived from 7 randomized placebo-controlled trials of pregabalin (150, 300, 600, and flexible 150 - 600 mg/d) for the treatment of postherpetic neuralgia (PHN) and 2 randomized placebo-controlled trials for the treatment of NeP due to spinal cord injury (SCI-NeP). On each day, patients rated the severity of their pain and pain-related sleep interference (PRSI) over the previous 24 hours on a scale from 0 to 10, with higher scores indicating greater severity. Patients were also continually monitored for the occurrence of adverse events. SETTING A pooled retrospective analyses of data from randomized clinical trials. METHODS Changes from baseline in mean weekly pain and PRSI scores were compared between patients who received concomitant NeP medications and patients who did not receive concomitant NeP medications. Results of these comparisons are presented separately for the PHN (through 4, 8, and 12 weeks) and SCI-NeP (through 12 weeks) cohorts. Common adverse events are also presented for each treatment group. RESULTS Pregabalin significantly improved both pain and PRSI scores relative to placebo at most dose levels and time points examined. Notably, little difference was observed in the extent of therapeutic response to pregabalin between patients who received concomitant NeP medications and patients who did not receive concomitant NeP medications. Additionally, the profile of treatment-emergent adverse events appeared to be largely unaffected by the use of concomitant NeP medications in the pooled patient population. LIMITATIONS Our analysis is limited in that the original trials of pregabalin were not powered to examine the effects of concomitant NeP medications. CONCLUSIONS The data presented here demonstrate that therapeutic response to pregabalin and the occurrence of adverse events in patients with NeP are generally unaffected by the concurrent use of other NeP medications.Trial Registration numbers: NCT00159666; NCT00301223; NCT00407745Key words: Pregabalin, neuropathic pain, pain-related sleep interference, concomitant medications, postherpetic neuralgia, spinal cord injury, efficacy, safety.