By Judith Moser, MD
BARCELONA, Spain -- September 1, 2008 -- According to a study presented here at the 21st European College of Neuropsychopharmacology Congress (ECNP), the antidepressant duloxetine reduces chronic pain effectively in depressive patients.
Principal investigator Juan Castaņo, MD, Primary Psychiatric Unit, IAPS, Hospital del Mar, Barcelona, Spain, and colleagues performed the study to evaluate the efficacy of duloxetine in treating painful physical symptoms that occur along with depression.
Several antidepressants reduce pain via a wide variety of actions on the neuroregulatory mechanisms associated with pain perception and transmission.
Serotonin and norepinephrine play a key modulating role in pain mechanisms in the central nervous system. Drugs like duloxetine, which inhibit the reuptake of these 2 neurotransmitters, are thought to reduce the nociceptive afferent transmission in the ascending spinal pathways.
The efficacy of duloxetine in a population of 40 patients meeting the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) criteria for major depression was prospectively tested. The patients suffered from chronic pain, with the most frequently reported locations being the back followed by the neck and limbs.
The patients received duloxetine 60 to 120 mg QD. "We started with 60 mg and increased the dosage in some patients according to their response," explained Dr. Castaņo in a poster presentation on September 1.
Efficacy measures included assessments with the 17-item Hamilton Rating Scale for Depression, the McGill Pain Questionnaire, and the visual analogue scale.
As Dr. Castaņo emphasised, concomitant diseases that underlie primary pain such as arthritis, fibromyalgia, and migraine headache were exclusion criteria.
The total response concerning depression, including remissions, was 67.5% with a duloxetine dosage of 60 mg QD. With duloxetine 120 mg QD, the estimated probability of remission was 65%.
In terms of pain, the total response was 57%, including patients in remission. At the higher dosage of duloxetine 120 mg QD, the probability of response was estimated at 20% and remission rates were 45%.
Improvements in pain severity occurred independently of changes in depressive symptom severity. There were no significant differences in terms of pain response between patients with severe and mild depression.
The investigators found a mild to moderate concordance between the pain and depression efficacy of duloxetine (Kappa coefficient 0.35; P = .002).
These results support the efficacy of duloxetine in the treatment of both pain and depression. "However, they only approached significance," Dr. Castaņo added. "Further studies will be required to understand the treatment of major depression in patients with coexisting pain symptoms to a greater extent. The depressive response alone does not explain the pain response."
The study did not receive industry funding.
[Presentation title: Efficacy of Duloxetine in Painful Symptoms With Major Depressive Disorder. P2a011]
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