May 30 (UPI) -- Ketamine nasal spray may be effective in treating chronic migraines, according to a new study.
Publishing in the open access journal Regional Anesthesia & Pain Medicine, researchers wrote that several clinical trials had shown the spray to be effective, but cautioned against overuse. They also said it wasn't clear if ketamine could be used to treat chronic migraines.
"This retrospective study suggests that [intranasal ketamine] may offer a pain-relieving effect with limited side effects for [refractory chronic migraine] in the outpatient setting," the study concluded.
The researchers worked in the Department of Neurology at Thomas Jefferson University in Philadelphia; Ohio Health; and Rush University in Chicago.
One of the key authors was Dr. Michael Marmura, an associate professor in the Department of Neurology at Thomas Jefferson and director of outpatient operations at the Jefferson Headache Center, as well as co-chief of the Division of Headache.
The researchers cautioned that the study involved primarily young White women and that most of the participants used the spray alongside other medications, which made it difficult to address the benefits of the spray itself.
The primary goal was to try to find out if ketamine could be used for chronic migraine that is resistant to treatment.
The researchers retrospectively reviewed the outcomes and experiences of people given nasal ketamine spray for chronic refractory migraine -- a persistent headache or one that fails to respond to treatments -- between January and February 2020 at the Jefferson Headache Center.
During the two months, 242 people were prescribed a nasal ketamine spray, and 169 of whom agreed to be interviewed. Eighty percent were women with an average age of 44.
More than 67% reported daily headaches and almost 85% had tried more than three kinds of preventive drugs. They currently used roughly two of these.
The most common reasons for wanting to use nasal ketamine spray included "partial responses to reliever painkillers (100, or 59%) and preventive drugs (52, or 31%), previous benefit from intravenous ketamine (38, or 22.5%), and the failure of intravenous lidocaine (22,or 13%)," the study said.
Forty one (25%) and 46 (28%) patients were offered nasal ketamine spray before and after intravenous ketamine infusion, respectively. Almost half never received intravenous ketamine.
Overall, the patients said they used the nasal spray six times over an average of 10 days a month. Nearly half (49%) said the spray was "very effective," while 39.5% found it "somewhat effective." More than one-third (35.5%) said their quality of life was "much better."
Compared with other reliever drugs, 73, or 43%, thought the nasal spray was "much better" and 50, or 29.5%, felt it was "somewhat better."
"Almost three quarters said they used fewer pain reliever meds when using nasal ketamine spray. At the time of the interview, almost two-thirds (65%) were still using the spray," the authors wrote.
Nearly 75 percent of participants reported at least one side effect, with fatigue and double or blurred vision the most common.
"Dependency is a potential drawback," the researchers said, "highlighting that their study showed 23 people used the spray daily and 37 used it more than 15 days a month," according to a news release.
"Clinicians should only consider the use of a potentially addictive medication such as ketamine for significantly disabled patients with migraine," the study said.
A recent study on ketamine also suggested that it may be an alternative to shock treatment for people with treatment-resistant major depression.