Nerve pain is caused by a condition called neuropathy. Neuropathy is a general term that means nerve damage. Types of neuropathy include motor neuropathy, which causes damage to the nerves that control muscles, and sensory ataxia, which causes incoordination because of damage to nerves related to balance. A common neuropathy involves paresthesia, in which a person experiences pain, numbness, tingling or burning sensations due to damaged nerves. Medications for nerve pain fall into three categories: treatments for the underlying condition causing the nerve damage; medications to help relieve the painful, uncomfortable sensations; and medications to treat depression, which may develop in people with long-standing nerve pain.
Gabapentin
Gabapentin is a medication that is used to treat seizures in epilepsy. It is also, however, used for treatment of nerve pain. It has a similar structure to the brain chemical gamma-aminobutyric acid (GABA). Despite the many things known about this medication, its mechanism of providing pain relief remains unknown. A study published in the journal Clinical Therapeutics by University of Wisconsin-Madison researchers, hypothesizes that perhaps the drug somehow influences calcium channels and reduces the sensation of pain. The most common side effects of gabapentin are dizziness and tiredness; other, more rare side effects include nausea and vomiting. Serious side effects are extremely rare and include seizures and a life-threatening drug reaction called Stevens-Johnson syndrome.
Amitriptyline
Amitriptyline is an antidepressant that falls into a class called the tricyclic antidepressants. They are called this because their molecule structure contains three rings of atoms. Amitriptyline and other tricyclics work by increasing the concentration of certain neurotransmitters, serotonin and possibly norepinephrine; however, it is not clear exactly how this reduces the pain of neuropathy.
According to the online medication database Micromedex, side effects include sedation, anxiety, and possible suicidal thoughts; weakness, tremor or blurry vision may occur. Other side effects may include rapid heart rate or decreased blood pressure, hives, rash, increased sensitivity to sun exposure, constipation, heartburn and discoloration of urine.
Duloxetine
Duloxetine is also an antidepressant; it falls into a class called serotonin-noradrenaline reuptake inhibitors. As with the other medicines used for neuropathy, it is not clear exactly why the drug works to reduce the pain of neuropathy. What is known is that duloxetine increases the concentration of the neurotransimitters serotonin and noradrenaline; however, it is not clear why this causes a decrease in pain sensation. Side effects include sleepiness/sedation, dizziness and sometimes insomnia. Other common reactions include nausea and vomiting, constipation and heartburn. Sexual side effects such as decreased sex drive and erectile dysfunction may occur as well, but these are less commonly seen.
Oxycodone
Oxycodone is an opioid analgesic; that is, it is a medication used for pain relief that is derived from opium. It works by binding to pain receptors all over the body and thus decreasing the sensation of pain. A significant concern in using oxycodone and other opiates is the potential for dependence and addiction to the medication. If patients are properly monitored by their physicians, however, this may be a good choice if other medications do not relieve the neuropathy symptoms. Oxycodone commonly causes sleepiness, dizziness and itchiness, especially in patients who have never been on this type of medication. Nausea, vomiting and constipation may also occur with this medication. Less frequently, patients may experience, headaches, insomnia or euphoric feelings.
Capsaicin
Capsaicin is a medication that is applied directly to the skin either in the form of a lotion or a cream. A capsaicin patch is also available. It works by causing an increase in the release of substance P, which is one of the primary molecules involved in transmitting the sensation of pain from the nerves to the brain. With repeated application of the cream, the amount of substance P decreases and is unable to re-accumulate in the nerve, so the nerve can't send a pain signal to the brain. Care must be taken when the cream/lotion is applied--in fact, it is recommended that gloves be worn when applying the medicine and that hands are washed with soap and water after application. This is done so that the cream does accidentally get put in the eye or other sensitive areas. Side effects of the medication include temporary burning sensation in the area of application, itching, stinging sensation and cough.
References
- "Harrison's Principles of Internal Medicine"; Anthony S. Fauci et. al.; 2008
- Micromedex: Amitriptyline
- "Current Medical Diagnosis and Treatment"; Stephen J. McPhee and Maxine Papadakis; 2010
- "Clinical Therapeutics": Gabapentin Dosing for Neuropathic Pain: Evidence from Randomized, Placebo-Controlled Clinical Trials; M. Backonja and R.L. Glanzman; January 2003
