Gabapentin and venlafaxine for the treatment of painful diabetic neuropathy.
OBJECTIVE
To evaluate the safety and efficacy of gabapentin and venlafaxine in the treatment of painful diabetic neuropathy in patients whose pain did not improve with gabapentin monotherapy.


METHODS
(1) A randomized, double-blind, placebo-controlled, 8-week clinical trial comparing gabapentin versus placebo to define a patient population whose pain did not improve with monotherapy; (2) a second 8-week trial comparing gabapentin plus venlafaxine with gabapentin plus placebo; (3) a third uncontrolled 8-week trial of patients who did not improve on gabapentin monotherapy and then received venlafaxine in addition to gabapentin.


RESULTS
(1) Gabapentin-treated patients showed statistically significant improvement in pain reduction as well as improvement in quality of life and mood disturbance when compared with placebo-treated patients; (2) patients who received gabapentin plus venlafaxine showed significant improvement in pain reduction, mood disturbance, and quality of life when compared with patients treated with gabapentin plus placebo; (3) patients who received gabapentin plus venlafaxine showed significant improvement in pain reduction, mood disturbance, and quality of life.


CONCLUSIONS
(1) Gabapentin is efficacious in the treatment of painful diabetic neuropathy; (2) and (3) in patients who do not respond to gabapentin monotherapy, the addition of venlafaxine is also efficacious.
Simpson
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From the Michigan Institute for Neurological Disorders, Farmington Hills, Michigan.