Effect of carbamazepine on pain scores of unipolar depressed patients with chronic pain: a trial of off-on-off-on design

Abstract

Objective: The purpose of this study was to evaluate the effect of carbamazepine on chronic pain in patients with major depression.

Design: Off-on-off-on carbamazepine treatment design.

Setting: Department of Anesthesiology, Hirosaki University Hospital, Japan.

Patients: Fifteen patients with a diagnosis of major depression and chronic pain.

Intervention: Depressed patients maintained on antidepressants that had failed to help depression or pain were initially placed on 450 mg carbamazepine at 150 mg three times per day. Carbamazepine was then increased until the patients experienced satisfactory relief of pain. This dose was then maintained for 3 weeks. Afterward, the medication was stopped, and a lactose placebo was administered orally three times per day for 3 weeks. Thereafter, carbamazepine was given for 3 additional weeks at the dose that previously produced satisfactory pain relief.

Outcome measure: Pain scores were assessed four times during the course of the study: before and after the first and the second treatments with carbamazepine, using a visual analog scale in which 0 represents no pain and 10 unbearable pain. The Hamilton Depression scale was used to judge improvement in the symptoms of depression.

Results: Carbamazepine produced a statistically significant reduction in the pain scores, from 8.2 +/- 2.3 to 4.0 +/- 1.1 after the first treatment. The pain score significantly increased to 8.0 +/- 1.0 after stopping carbamazepine, but it decreased significantly to 4.1 +/- 1.8 after the second treatment. The Hamilton scores significantly decreased from 27.4 +/- 7.2 to 20.2 +/- 6.1 after the carbamazepine treatment.

Conclusions: These results may indicate that carbamazepine has both an antidepressive and an analgesic action in depressed patients. Thus, carbamazepine may offer an acceptable therapeutic option in depressed patients with chronic pain that is unresponsive to antidepressants. Alternatively, these results may indicate that carbamazepine appears to help depression in this group of pain patients because of its analgesic effect (i.e., helps depression as a result of helping pain or vice versa).