Ketamine Infusions Effective in Reducing Fibromyalgia Pain
/By Pat Anson
Ketamine infusions provided “substantial and sustained” relief for women suffering from severe symptoms of fibromyalgia, according to a small new study. But the results were uneven, with some patients reporting over 50% pain relief, while others had minimal or no benefit despite multiple treatments.
Fibromyalgia is a poorly understood disorder characterized by widespread body pain, fatigue, headaches, brain fog and insomnia. About 3% of the world’s population has fibromyalgia, most of them women.
For the study, researchers at the Carolinas Pain Institute enrolled 92 women suffering from chronic fibromyalgia, ranging from 24 to 78 years of age. Their median pain score at the start of the study was 8 on the zero to ten pain scale. About a third of them were on opioid pain medication.
Ketamine is an anesthetic drug that is only FDA-approved for depression and anesthesia, but is increasingly used off-label for chronic pain conditions such as Complex Regional Pain Syndrome.
Participants received 1.5 mg/kg per hour of ketamine during 3-hour infusion sessions, which were repeated as needed every 3 to 10 months. Some patients needed only one infusion, while others needed as many as 32 infusions.
The study findings, reported recently in the Journal of Pain Research, show the median pain score for the women fell from 8 to 5 after three months. About a third reported more than 50% pain relief – improvements that were sustained for 24 months.
“Although the duration of pain relief varied between patients, it was generally consistent for each individual patient and averaged approximately 6 months, which was considered highly satisfactory by most patients undergoing repeated infusions,” wrote lead author Leonardo Kapural, MD, an anesthesiologist at the Carolinas Pain Institute in North Carolina.
“Clinically meaningful improvement, defined as at least a two-point reduction on the pain scale, was achieved in 75% of patients through 24 months, suggesting that the majority of patients with severe fibromyalgia benefited from this therapy.”
But 19 patients – about 20% of the participants – reported minimal or no benefit from treatment. Nineteen patients also experienced side effects, such as nausea, vomiting, hallucinations, confusion, and nightmares.
It is common for patients to experience dissociation and “out of body” sensations during ketamine infusions. They appear to be awake, but are often unable to respond or react to sensory input.
Researchers say there were numerous changes in medication for the 92 participants during treatment. The number of patients taking opioids fell from 33 to 27. Others continued taking antidepressants, muscle relaxants, and anti-inflammatory medications. Because of that, it is difficult to say if ketamine is best used alone or as an adjunct therapy used in combination with medication.
Despite those limitations, researchers say their findings of substantial pain relief from chronic fibromyalgia justifies a larger clinical trial with ketamine infusions. Previous small studies of ketamine as a treatment for fibromyalgia also suggest that infusions could be beneficial.
Until recently, there were only three FDA-approved drugs for fibromyalgia: duloxetine (Cymbalta), pregabalin (Lyrica), and milnacipran (Savella). Many patients consider the drugs ineffective or have too many side effects.
Last year, the FDA approved Tonmya, a fourth drug for the treatment of fibromyalgia in adults. Tonmya is a new formulation of a muscle relaxer (Flexeril), which was originally developed as an antidepressant.
