PHN Treatment: Antidepressants

To treat neuralgia, specifically trigeminal and postherpetic neuralgia, physicians typically begin by prescribing antidepressants, anti-convulsants, or anti-spasticity drugs. Normally, antidepressants function by regulating levels of serotonin, dopamine, and norepinephrine in the brain to increase the sensitivity of nerve cells to glutamate, which is a non-essential amino acid linked to anxiety and depression, as well as the way one's body interprets pain; however, these medications are usually prescribed in smaller doses for neuralgia patients. Specifically, tricyclic antidepressants (which also affect nervous sodium channels) are usually prescribed to patients suffering from postherpetic neuralgia (PHN), rather than trigeminal or glossopharyngeal neuralgia.

These antidepressants should ease nerve pain within a few days, although they can also take up to several weeks to begin working fully, and are less effective in patients with burning pain or pain triggered by external stimuli. They are more effective when started within the first year after symptoms occur. Patients usually become dissatisfied with medication therapy, because it only moderates the pain and nerve pain can re-emerge unless dosage is increased over time (this is actually a phenomenon that has developed among patients suffering depression; no scientific correlation to neuralgia patients has been established). Side effects for tricyclic antidepressants include: dry mouth, constipation, bladder problems (especially in men with enlarged prostrate conditions), impaired sexual function, dizziness, drowsiness, blurred vision, increased heart rate, and weight gain. Unfortunately, side effects are more severe in the elderly- who are more at risk for neuralgia.

Nortriptyline (Pamelor, Aventyl), amitriptyline (Elavil, Endep), and desipramine (Norpramin) are standard drugs, but desipramine and nortriptyline have fewer side effects than amitriptyline and are preferred for older patients. In a study published in 2005 by the UCSF Pain Clinical Research Center, Michael Rowbotham treated postherpetic neuralgia patients with desipramine, amitriptyline, and fluoxetine. He concluded that: "Desipramine produced the greatest reduction in pain intensity (47%), followed by amitriptyline (38%) and fluoxetine" (Journal of Pain, Vol. 6, Issue 11). Additionally, he found that fluoxetine exhibited the most severe side effects: "The fluoxetine group had the highest noncompletion rate, with 1 subject hospitalized for hyponatremia. Although the magnitude of pain reduction and the category pain relief rating was not significantly different among the 3 drugs, the tricyclics desipramine and amitriptyline were well tolerated and provided clinically meaningful pain relief in 53% to 80% of subjects."


Antidepressants for neuralgia include:

- Amitriptyline: Elavil, Amitril, Emitrip, Endep, Etrafon, Levate, Limbitrol, Novotriptyn, Triavil. This is the most commonly used antidepressant for neuralgia treatment, and in most cases it does NOT demonstrate a loss of affectivity over time.

- Protriptyline: Vivactil

- Nortriptyline: Aventyl, Pamelor

- Desipramine: Norpramin

- Duloxetine: Cymbalta

- Fluoxetine: Prozac (US), Seronil, Fontex (Europe). The use of fluoxetine to treat neuralgia is more experimental, and often used only as an alternative to oter antidepressants, due to its higher cost.