Doxepin's effects on chronic pain and depression: a controlled study.

Sixty patients with chronic pain of the low back or cervical spine concomitant with clinical depression were studied in a 6-week, randomized, double-blind comparison of doxepin and placebo. Significant improvements in the doxepin-treated group compared to placebo or to baseline values were seen on Hamilton depression scores, Global Assessment Scale scores, pain severity, percent of time pain felt, and effect of pain on activity, sleep, and muscle tension. Some improvements were observed after 1 week of treatment; the most improvement occurred at 6 weeks, when the mean doxepin dosage was approximately 200 mg/day and plasma doxepin and nordoxepin averaged 80 ng/ml. No significant harmful effects were observed. Neither plasma beta-endorphin nor enkephalin-like activity demonstrated significant differences from baseline. These data indicate that doxepin is a valuable treatment for patients with chronic pain and depression.