This randomized, double-blind, placebo-controlled study was undertaken to evaluate the efficacy and tolerability of
lamotrigine added to
gabapentin, a
tricyclic antidepressant, or a
nonopioid analgesic in patients whose
neuropathic pain was inadequately controlled with these medications. Patients with
neuropathic pain from diabetic
peripheral neuropathy,
postherpetic neuralgia, traumatic/surgical nerve injury, incomplete
spinal cord injury,
trigeminal neuralgia,
multiple sclerosis, or HIV-associated
peripheral neuropathy, who had a mean weekly
pain score > or =4 on an 11-point numerical rating scale, were randomized to receive a flexible dose of
lamotrigine 200, 300, or 400mg daily (n=111) or placebo (n=109) for up to 14 weeks (including eight weeks of dose escalation) in addition to their prestudy regimen of
gabapentin, a
tricyclic antidepressant, or a
nonopioid analgesic. No statistically significant difference in the mean change in
pain-intensity score from baseline to Week 14 (primary endpoint) was detected between
lamotrigine and placebo (P=0.67). Differences between
lamotrigine and placebo were not statistically significant for secondary efficacy assessments, including mean changes from baseline in the Short-Form McGill
Pain Questionnaire, the
Neuropathic Pain Scale, rescue medication use, and the percentages of patients rated as much improved or very much improved at the end of treatment on the Clinician Global Impression of Change scale and the Patient Global Impression of Change scale.
Lamotrigine was generally well tolerated.
Lamotrigine (up to 400 mg/day) added to
gabapentin, a
tricyclic antidepressant, or a
nonopioid analgesic did not demonstrate efficacy as an adjunctive treatment of
neuropathic pain but was generally safe and well tolerated.