Amitriptyline is a tricyclic antidepressant drug which was originally developed to relieve symptoms of depression. It is known as an adjuvant medication, that is, its medicinal properties have been found useful in treating neuropathic pain even though its formulation was developed to treat depression.
Antidepressants have two roles in managing chronic pain. The main role is to provide pain relief when conventional analgesics such as NSAIDS, paracetamol through to morphine haven't been effective or when these analgesics have been found to have intolerable side effects. The failure of conventional analgesics for neuropathic, for example, spinal cord injury (pain in a numb area) may justify a trial of amitriptyline which has shown to be effective for both burning and shooting pain.
A secondary role of antidepressants in treating chronic pain is their use in combination with conventional analgesics. This can be effective in people with chronic pain eg cancer, who have pain at multiple pain sites or have a combination of both nociceptive and neuropathic pain. Improving sleep is also highly important.
The process by which this drug works is by increasing the levels of particular chemicals in the brain, which overall affects the central nervous system (CNS). In clinical trials Amitriptyline has been tested on neuropathic pain including: postherpetic neuralgia, diabetic neuropathy, irritable bowel syndrome, temperomandibular joint disorder, facial pain and fibromyalgia. It has been found to benefit pain, sleep, and fatigue levels.
Amitriptyline is prescribed in much lower doses for pain than would be needed to treat depression. The speed of effect is also much faster, approximately one week, than occurs in treating mood for depression.
The most common side effects include drowsiness and dry mouth, which occur in one third of cases. These adverse effects are very similar as when the drugs are used to treat depression. Amitriptyline is generally prescribed at night and if the person is still drowsy in the morning they should try taking the medicine earlier in the evening. There are fewer incidences of side effects for newer antidepressants (selective serotonin reuptake inhibitors) than with the older tricyclic drugs which may make them worth trying for those patients who cannot take tricyclics because of adverse effects.
It is important that when taking this form of medication, that you do not miss your recommended doses and that you follow the recommended amount as informed by your doctor. It is also strongly recommended not to increase or lower the dose of the recommended amount if you have not spoken to your treating doctor about this change or to just stop taking this medication completely, as this may result in increased side effects.