Treatment of depression and anxiety for back pain

According to primary medical care requests, up to 80% of patients suffering from depression present complaints of an exclusively somatic nature, such as headaches, abdominal pain, muscle pain in the back, joints, and neck. The question arises as to why the painful somatic manifestations that are so common in depression are not sufficiently reflected in the diagnostic guidelines for this disease, although in many cases they may be the only signs of depressive disorder?

One possible reason for this is that such complaints are usually attributed to a somatic disease, especially in therapeutic practice. In cases where complaints are limited to increased fatigue, loss of strength, and painful somatic manifestations, and there are no clear affective and vegetative symptoms, many doctors are inclined to an often exhausting search for somatic pathology. In turn, the suspicion of a depressive or anxiety disorder in a patient usually arises when his complaints are predominantly psychological or emotional in nature. Another common mistake is that the goal of therapy for patients suffering from depression is simple improvement of the condition, rather than achieving remission. Currently, the recommended standard of care for patients with depression is the complete elimination of all symptoms: not only emotional, vegetative, but also painful somatic manifestations of this disease.

Read also: 8 Things You Need to Know About Antidepressants

Antidepressants are the fastest growing group of psychotropic drugs. It is enough to cite some figures. Thus, over the last 15 years, 11 innovative antidepressants have been registered, including venlafaxine and duloxetine in the last two years.

Currently, at least 10 different classes of antidepressants have been identified, based on the monoamine theory. They are grouped according to their chemical structure - tricyclic antidepressants (amitriptyline, melipramine, clomipramine, etc.), specific or selective mechanism of action - MAO inhibitors (MAOI - phenelzine), reversible MAO type A inhibitors (moclobemide, pirlindole), selective serotonin reuptake inhibitors (fluvoxamine, fluoxetine, paroxetine, sertraline, citalopram, escitalopram), selective norepinephrine reuptake inhibitors (reboxetine), selective serotonin reuptake stimulants (tianeptine), norepinephrine and serotonin reuptake inhibitors (venlafaxine, duloxetine), norepinephrine and dopamine reuptake inhibitors (bupropion), noradrenergic and specific serotonergic (mirtazapine) and serotonin antagonists and reuptake inhibitors (nefazodone).

Numerous studies have shown that dual-action antidepressants (selective serotonin and norepinephrine reuptake inhibitors) used to treat depression may also be effective in treating chronic pain; dual-action drugs such as tricyclic antidepressants (amitriptyline, clomipramine) and venlafaxine, or combinations of antidepressants with serotonergic and noradrenergic effects, have demonstrated greater treatment efficacy than antidepressants that act primarily on one neurotransmitter system.

Dual action (serotonergic and noradrenergic) also results in a more pronounced effect in the treatment of chronic pain. Both serotonin and noradrenaline participate in pain control via the descending pain pathways (DPP). This explains the advantage of dual-action antidepressants for the treatment of chronic pain. The exact mechanism by which antidepressants produce an analgesic effect remains unknown. However, dual-action antidepressants have a longer-lasting analgesic effect than antidepressants that act on only one of the monoaminergic systems.

Tricyclic antidepressants (amitriptyline) and serotonin and norepinephrine reuptake inhibitors (venlafaxine, duloxetine) have shown the greatest effectiveness in treating patients with chronic pain, and their analgesic effect is believed to be not directly related to their antidepressant properties.

Amitriptyline is the most preferred drug for treating pain syndromes. However, it has a significant number of contraindications. The main mechanism of action of tricyclic antidepressants is to block the reuptake of norepinephrine and serotonin, which increases their amount in the synaptic cleft and enhances the effect on postsynaptic receptors. In addition, amitriptyline is able to block sodium channels of peripheral nerve fibers and neuronal membranes, which allows suppressing ectopic generation of impulses and reducing neuronal excitability. The side effects of tricyclic antidepressants are due to the blockade of beta-adrenergic, antihistamine (HI) and acetylcholine receptors, which significantly limits their use, especially in elderly patients.

They also have undesirable interactions with opioid analgesics, MAO inhibitors, anticoagulants, antiarrhythmics, etc.). Amitriptyline has been shown to be highly effective in acute and chronic neuropathic pain syndromes, as well as chronic back pain, fibromyalgia. The effective dose of the drug for the treatment of pain syndrome may be lower than the dose used to treat depression.

Venlafaxine has recently been widely used to treat pain syndromes, both associated with depression and without it. Venlafaxine in low doses inhibits the reuptake of serotonin, and in higher doses - norepinephrine. The main analgesic mechanism of venlafaxine is due to its interaction with alpha2- and beta2-adrenergic receptors. modulating the activity of the antinociceptive system (raphe nuclei, periaqueductal gray matter, blue spot). To date, convincing data have been accumulated on the high clinical efficacy of venlafaxine in the treatment of various pain syndromes. Clinical studies indicate that the use of venlafaxine is a good treatment method for patients with chronic pain syndromes in the context of major depressive or generalized anxiety disorder. This is important because more than 40% of patients with major depressive disorder have at least one pain symptom (headache, back pain, joint pain, pain in the extremities, or gastrointestinal pain). The use of venlafaxine can reduce both the level of depression and the severity of pain. Venlafaxine-XR is prescribed for major depressive disorder, generalized anxiety disorder, and social anxiety disorder in doses of 75 to 225 mg/day. For some patients, low doses of venlafaxine may be effective. Treatment can be started with 37.5 mg/day, with a gradual increase in the dose over 4-7 days to 75 mg/day.

The studies conducted have shown that the analgesic effect of venlafaxine is due to mechanisms unrelated to depression. In this regard, venlafaxine has also proven effective in pain syndromes unrelated to depression and anxiety. Although indications for the use of venlafaxine in chronic pain have not yet been included in the instructions for its use, the available data indicate that a dose of 75-225 mg/day is effective in most pain syndromes. Data from randomized, controlled studies have shown that pain relief occurs 1-2 weeks after the start of treatment. Some patients require a 6-week course of treatment to achieve a good analgesic effect of venlafaxine.