Clinical Drug Experience Knowledgebase

Pain is an unpleasant sensory and emotional experience. Chronic pain, including chronic low back pain, represents a major public health problem. Risk factors of chronicity of low back pain include high levels of psychological distress prior to or during the episode, premorbid association with work status or employment dissatisfaction, unemployment, poor self-rated health and low levels of physical activity. Other psychosocial features are poor social and educational status, previous sexual or physical abuse. Furthermore, mechanical strain on the spine from heavy lifting, repetitive lifting, twisting and vibration, including driving increase the risk. Static work postures, prolonged standing or walking, road traffic accidents and falls are also significantly related.While there is little evidence for a specific personality profile, stress, distress, anxiety, mood disorders and depression were consistently related to neck and back pain.

CLBP is associated with significant disability, functional impairment, high rates of psychiatric symptoms including anxiety and depression, and loss of other physical roles. These may produce social and functional problems, which include reduced earning capacity, unemployment and family disharmony. Chronic pain is also associated with loss of self confidence and self-esteem, leading to social withdrawal and social isolation. Men with CLBP have significantly higher lifetime rates of major depression, alcohol use disorder and major anxiety disorder. After age of pain onset, CLBP subjects had over 9 times the risk of developing major depression.

Depression is believed to be mediated by 5-HT and norepinephrine through the raphe nucleus and locus coeruleus projections to the cerebral cortex and forebrain limbic systems, whereas pain is believed to be mediated in part through descending 5-HT and norepinephrine pain pathways that provide inhibitory input to the dorsal horn neurons in the spinal cord. Global deficiences in 5-HT or norepinephrine neurotransmission would be predicted to affect both mood and pain thresholds, possibly accounting for the hgh comorbidity of painful symptoms in patients with depression.Accordingly, enhancement of both neurotransmitter or 5-HT alone would be expected both to improve symptoms of depression and to normalize pain thresholds.

In antidepressant treatment of CLBP, only 2 studies were published using SSRIs. One reported significantly higher pain intensity reduction in maprotilin group compared to paroxetine and placebo. The other showed no effect of paroxetine on depression or pain. Patients on SSRI, however, reduced the amount of analgesic medication.