Efficacy and Safety of Antidepressants as Analgesics in Chronic Pain: A Review

Introduction Due to the aging population worldwide, chronic pain is becoming an important public health concern. Chronic pain is bidirectional associated with psychiatric disorders including depression and anxiety. Antidepressants are widely used as adjuvant therapy for the treatment of chronic pain for many disorders. Objectives and aims To review available literature on the efficacy and safety of antidepressants for the treatment of chronic pain, including neuropathic pain, fibromyalgia, low back pain, and chronic headache or migraine. Methods We performed a detailed literature review through PubMed, EMBASE and Cochrane's Library to assess the efficacy and safety of antidepressants in chronic pain conditions. Results In neuropathic pain, fibromyalgia, low back pain, and chronic headaches/migraine, tricyclic antidepressants (TCAs) showed a significant analgesic effect. Selective serotonin reuptake inhibitors (SSRIs) are not effective for the treatment of low back pain and headaches or migraine. Venlafaxine, a serotonin norepinephrine reuptake inhibitor (SNRI) showed significant improvement of fibromyalgia and neuropathic pain. Duloxetine (SNRI) also reduced the pain in fibromyalgia. Conclusion TCAs are the ‘gold standard’ antidepressant analgesics. However, an electrocardiogram and postural blood pressure should be implemented prior to TCA treatment and TCAs should be initiated at low dosages and subsequently increased to the maximum tolerated dose. One should pay attention to their cardiotoxic potential, especially in the older population. For the treatment of neuropathic pain, SNRIs are second-line agents. Although better tolerated, in most types of chronic pain conditions, the effectiveness of SSRIs is limited. To conclude: start low, go slow, and prescribe with caution. Disclosure of interest The authors have not supplied their declaration of competing interest.