The preliminary results of a new study have found that Botox, better known for getting rid of wrinkles, significantly reduced severe pain from osteoarthritis of the knee and also improved the knee's function.
Botox is a purified form of botulinum toxin type A and is used to treat wrinkles and creases on the face.
Botox is also approved to treat other conditions including excessive sweating, eye disorders, and certain neurological conditions and is currently being studied for the treatment of headaches, ringing in the ears, overactive bladder, and diabetic nerve pain.
According to Dr. Maren Mahowald, a rheumatologist at Minneapolis VA Medical Center, although the study is not yet complete, or the results reviewed, they are excited by what they have already seen.
Dr. Mahowald presented her data at the American College of Rheumatology meeting and says the trial grew out of clinical observations in conditions such as painful spasticity, in which investigators noticed that pain often lessened before a decline in muscle contractions.
Dr. Mahowald says this suggested an independent analgesic effect of botulinum toxin, so she and her colleagues conducted an open-label study, in which they found 10 of 15 patients had an improvement in pain by up to 50% or more.
The current study has enrolled 37 patients who are not candidates for joint replacement, and the team are evaluating their response at one, three, and six months to injections of either 100 units of botulinum toxin plus lidocaine or saline plus lidocaine.
Mahowald says all patients have now been evaluated at the one-month mark, and the researchers saw no effect among the 17 patients with moderate only pain.
After one month, people with severe pain showed a 28% decrease in pain and a 25% improvement in function.
By contrast, people with severe knee pain who received a placebo did not show a significant decrease in pain.
Dr. Mahowald says there were no significant adverse events, and the most common, muscle weakness, did not occur.
Experts say the preliminary results are provocative and the possibility of something non-toxic to use for such painful conditions would be fantastic.
But they caution that the study is incomplete as yet and doctors will need to look closely at variations in response among patients that might be masked by averages reported in a clinical trial.
Some people with knee osteoarthritis are too young for the surgery while others are too old and the nonsteroidal anti-inflammatory drugs, which are commonly taken to relieve the pain of knee osteoarthritis, are not without risks, such as gastrointestinal problems and increased risk of heart attack or stroke.
There are also risks from long-term use of opioid pain killers, including risk of addiction.