Gabapentin and Fibromyalgia

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Gabapentin and fibromyalgia have become more frequently linked in recent years. Gabapentin (generic name for the drugs Neurontin and Horizant) is a medication commonly prescribed for individuals with epilepsy and other seizure disorders, as well as for the nerve pain associated with diabetes, herpes, and shingles (a version of the “chicken pox”). In addition, Gabapentin has been tested as a drug treatment for individuals who suffer from Fibromyalgia, and for those with restless leg syndrome. Despite its widespread use, it is important to note that Gabapentin can only treat the symptoms associated with these conditions, including Fibromyalgia; it is not a cure. Successful management of the symptoms of Fibromyalgia generally involves multiple types of treatment which may include prescription medications such as Gabapentin but will likely also include exercise, focused therapies, pain management strategies and dietary changes or supplements.

Gabapentin is taken either as a tablet, capsule, extended release capsule, or liquid. Each specific brand of Gabapentin is prescribed differently. The extended release brand – Horizant – should be taken at 5pm in the evening, with food. Neurontin can be taken at any time of the day, with or without food. The normal adult dose of Gabapentin is 300 mg by mouth on the first day, 300 mg by mouth twice a day on the second day, and 300 mg by mouth three times a day on the third day. From day four on, doses typically range from 900 to 1,800 mg by mouth and are divided by three so that the medication is taken three times per day. Gabapentin should always be taken on a regular schedule in three doses, eight hours apart. Some studies have investigated the use of as much of 2,400 per day in patients and have found the drug to be generally well-tolerated (see below).

Potential Risks and Side Effects

 As with any medications, there are risks involved with taking Gabapentin. For some individuals, it may cause anxiety, depression, agitation, hostility, restlessness, mental or physical hyperactivity, and suicidal thoughts. It is important to communicate with your doctor if you have increasing thoughts of suicide as your treatment progresses or whenever your dose is changed.

 The use of certain medications while taking Gabapentin can alter its effectiveness. Using antacids within two hours of taking Gabapentin may make it more difficult for your body to absorb the medication. Other drugs that will affect the functioning of Gabapentin in the body include hydrocodone (Vicodin), morphine, and naproxen (Aleve, Naprosyn).

 Allergic reactions are also possible; signs and symptoms of an allergic reaction to Gabapentin include hives, fever, swollen glands, sores around the eyes or mouth, difficult breathing, and swelling of the face, lips, and tongue. Additional possible side effects include tingling, numbness, pain, muscle weakness, jaundice (yellowing of the skin), difficulty urinating, dark urine, confusion, cough, fever, rapid eye movements, blurred vision, and impaired thinking.

 People with kidney, liver, or heart disease, and those with restless leg syndrome who sleep during the day (or work the night shift) should consult their doctor to see if it is safe to take Gabapentin.

Research

 One study published in 2007 by Arnold et al. looked at the safety and effectiveness of Gabapentin to treat pain in patients with Fibromyalgia. The researchers randomly assigned 150 patients to receive either treatment with Gabapentin or treatment with a placebo (sugar pill or “fake” pill). Seventy-five patients were in each group. The dosing was done in increasing intervals of 300 mg over a six week period, up to a maximum dose of 2,400mg if the patient could tolerate it. If the patient could not tolerate the 2,400 mg dose, the dose was lowered to a minimum daily dose of 1,200 mg per day. To measure the effectiveness of Gabapentin on the symptoms of Fibromyalgia, patients were required to complete a series of questionnaires to measure their pain severity and various components of health status that are commonly affected by Fibromyalgia.

At the end of the study, those patients who received Gabapentin had significantly greater reductions in their level of pain than those who received placebos. Fifty-one percent of patients in the Gabapentin group had improved pain severity compared with only 31% of patients in the placebo group. They also showed greater improvements in health status (including improvements in sleep quality) over those patients who received the placebo. Nearly 70% of patients treated with Gabapentin indicated that their overall health status related to Fibromyalgia had improved at the end of the 12-week period, versus only 35% in the placebo group.

This study also sought to evaluate the safety of Gabapentin when used as a treatment for Fibromyalgia pain. Of the 150 patients, 19 withdrew over the course of the study due to side effects from the Gabapentin. Twelve were from the Gabapentin group and seven were from the placebo group. The most common side effects for those taking Gabapentin included dizziness, sedation/sleepiness, lightheadedness, and weight gain.

Although the overall findings of decreased pain and improved health status are promising, there are a few important things to consider regarding this study. First, the authors only treated patients with Gabapentin for a twelve week period, therefore their findings may not be reflective of the outcomes for patients who are treated with Gabapentin for longer periods of time. In addition, the study groups contained relatively low numbers of subjects, so future studies in larger groups of patients are needed. Finally, since each patient’s dose of Gabapentin varied depending on how well they tolerated the medication, the researchers were unable to determine the most effective dose needed to effectively treat the pain associated with Fibromyalgia. Therefore, although these findings show that Gabapentin is generally safe and effective as a treatment for Fibromyalgia when taken for up to twelve weeks, additional studies are needed.

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References

1.        Arnold LM, Goldenberg DL, Stanford SB, Lalonde JK, Sandhu HS, Keck PE Jr, Welge JA, Bishop F, Stanford KE, Hess EV, Hudson JI. Gabapentin in the treatment of Fibromyalgia. Arthritis & Rheumatism. 2007;56(4):1336-1334.

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