Venlafaxine as an analgesic in the treatment of chronic pain in patients with depression – scientific evidence and clinical cases

Depression is sometimes referred to as the state of “mental pain” as its symptoms generate a state of generalised suffering. Mental distress is very often accompanied by physical pain. The prevalence of somatic symptoms in the population of patients with depression varies significantly depending on the study population and ranges from 30 to 95%. The incidence and severity of pain are correlated with the aging process and they tend to increase with age. The most common pain symptoms in depression include headache, back and lower back pain, pain of joints and limbs, migraine headaches and abdominal pain. The pain may sometimes mask depression by coming to the fore in the clinical picture and making it difficult to establish an accurate diagnosis. The fact that antidepressants are effective in chronic pain syndromes, while not all antidepressants show the same analgesic efficacy, is the direct evidence for the common pathogenetic mechanisms of chronic pain and depression. Tricyclic antidepressants were the first antidepressants to be used in the treatment of pain symptoms in various disease states. Numerous studies have confirmed the analgesic efficacy of serotonin and noradrenaline reuptake inhibitors, which are characterised by a much better tolerance and a more favourable safety profile compared to tricyclic antidepressants; however, their analgesic effect is clearly marked only at doses that, in addition to the effect on serotonergic transmission, also affect the noradrenergic transmission. The article summarises the scientific evidence for the purposefulness of the use of venlafaxine in the treatment of chronic pain, in particular pain syndromes associated with depression, and presents two clinical cases with a commentary.