by Maija Haavisto
Jazz Pharmaceuticals is seeking FDA approval for Xyrem (sodium oxybate) for fibromyalgia. It is a sleep aid and muscle relaxant, which increases growth hormone secretion.
Fibromyalgia is strongly associated with poor sleep. Some doctors even believe it is the cause of fibromyalgia pain, as sleep deprivation is associated with increased secretion of inflammatory cytokines like IL-6, which can cause pain and other symptoms. IL-6 in particular is associated with hyperalgesia, or increased sensitivity to pain.
Whether or not fibromyalgia is essentially a sleep disorder, impaired sleep can certainly worsen pain, fatigue and other symptoms like depression. Jazz Pharmaceuticals has applied for FDA approval for a drug called Xyrem (JZP-6) in fibromyalgia. It is a novel kind of sleep aid with some interesting properties.
What Is Xyrem?
Sodium oxybate is the sodium salt of gammahydroxybutyric acid or GHB, a substance naturally present in the body. It works through GHB receptors and possibly GABAB receptors (many sleep aids like benzodiazepines bind to GABAA receptors). It has been used in medicine for decades, but recreational use and other abuse has slowed its development.
Xyrem is currently indicated in the treatment of narcolepsy. It is also used off-label as a sleep aid and has helped people who have been refractory to all other treatments. It is known to have muscle relaxant and antidepressant properties.
Xyrem has been shown to increase secretion of growth hormone, which may explain why it is so effective in fibromyalgia. Many studies have shown that growth hormone secretion is low in fibromyalgia and that growth hormone supplementation can reduce symptoms. Growth hormone therapy, while safe and effective, is extremely expensive and has to be given by injection.
Several studies have been done of Xyrem in fibromyalgia, showing that not only it improves sleep, but also pain and fatigue levels. It is also being studied in chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME), which is similarly associated with a growth hormone deficiency.
Currently Xyrem is only available through a special program in the United States and is a Schedule III drug, but the company behind it, Jazz Pharmaceuticals, has applied for extending its indication to fibromyalgia. The FDA will have to make a decision by the end of 2010. In some countries Xyrem is available without any restrictions, but tends to be extremely expensive.
Xyrem Side Effects and Drug Interactions
Unlike e.g. benzodiazepines, sodium oxybate does not cause dependency or tolerance when used according to the instructions. It also does not usually produce morning grogginess or other after effects. It can cause nausea, confusion, headache, tremor and dizziness, but is usually well-tolerated.
Sodium oxybate can dangerously potentiate the effects of other sedative drugs, herbs and alcohol. Other than that it has no known drug interactions. It could thus be combined with other fibromyalgia treatments, such as Savella, Lyrica, Cymbalta or low dose naltrexone.
Alternatives to Xyrem
Those who cannot get sodium oxybate may have a similar alternative in baclofen (Lioresal). It is classified as a muscle relaxant, but also works well to improve sleep. Baclofen appears to have somewhat similar mode of action to sodium oxybate and has also been shown to increase growth hormone secretion.
Baclofen has never been studied in fibromyalgia, but many doctors prescribe it for this use. It has also been used in the treatment of e.g. neurological symptoms, acid reflux (GERD), trigeminal neuralgia, tinnitus, hyperacusis and nystagmus. It may also improve tolerance to heat and cold.
Haavisto Maija. Reviving the Broken Marionette: Treatments for CFS/ME and Fibromyalgia. 2008.
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