Medications For Treatment Of Neuropathic Pain (Nerve Pain)
What is Nerve Pain?
Neuropathic pain or nerve pain is defined as pain initiated or caused by a primary lesion or dysfunction in the nervous system. Typically, lesions are seen in the pathways of the peripheral and central nervous system. The primary functions of nerves in the nervous system are to instruct muscles to move and to detect physical sensations like pain, temperature, and touch. When the nerves are damaged or diseased, it results in muscle weakness, and/or sensory disturbances. The nerves of the hands, arms, legs, and feet are affected the most, resulting in nerve pain in these areas.
Nerve Pain Medications
1. Tricyclic antidepressants (desipramine, nortriptyline)
Tricyclic antidepressant (TCA) medications work by inhibiting the reuptake of norepinephrine and serotonin. They are first line treatments for nerve pain. There are secondary TCAs and tertiary TCAs. Tertiary TCAs (amitriptyline, and imipramine) were first developed and approved before secondary TCAs. The secondary TCAs desipramine and nortriptyline are preferred for treating nerve pain.
Efficacy of tricyclic antidepressant
There are a large number of placebo-controlled randomized trials (RCTs) that show that TCA’s are effective for treating neuropathic pain. It takes 6 to 8 weeks to the see the full effects of tricyclic antidepressants. One in every 2-3 patients with peripheral neuropathic pain will respond to a tricyclic antidepressant. TCAs are inexpensive and they are commonly used for treating nerve pain, but their use is associated with many side effects.
Common Side Effects of Tricyclic antidepressants
Serious Side Effects of Tricyclic antidepressants
Side effects can be reduced if lower dosages are administered initially at bedtime and the dose should be slowly increased to a higher dose if needed. Secondary TCA’s (nortriptyline and desipramine) have less severe side effects when compared to tertiary TCA’s (amitriptyline and imipramine).
2. Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs) (duloxetine, venlafaxine)
Serotonin and norepinephrine reuptake inhibitors (SNRIs) are recommended as first line therapy for treating neuropathic pain. Duloxetine (Cymbalta) is FDA approved for nerve pain. Venlafaxine (Effexor) is used off-label for treating nerve pain.
Efficacy of Serotonin and Norepinephrine Reuptake Inhibitors for Nerve Pain
SSNRIs will relieve nerve pain in one of every 4-5 patients. They are preferred over TCA’s due to their more favorable side effect profile. In clinical studies, duloxetine has shown consistent efficacy in neuropathic pain. Venlafaxine has shown efficacy in nerve pain as well. Typically, 4 to 6 weeks of treatment is required to adequately judge the response to treatment.
Side Effects of Serotonin and Norepinephrine Reuptake Inhibitors
The most common adverse effect of duloxetine is nausea. Nausea seems to be less if dosing starts at 30 mg once daily for 1 week, then increased to 60 mg once daily. Venlafaxine causes a withdrawal syndrome so it should be tapered when treatment is discontinued.
Common Side Effects of SNRIs
Serious Side Effects of SNRIs