Taking an experimental drug called tanezumab along with a common pain medicine can help osteoarthritis symptoms, a study suggests. However, the chance of side effects from this combined treatment seems to outweigh the benefits.
Osteoarthritis is the most common condition affecting the joints. Many people get osteoarthritis in their knees or hips, which makes them stiff and painful. Some people end up having surgery to replace the affected joint, but many people take medicines to help with their symptoms. Non-steroidal anti-inflammatory drugs (NSAIDs), such as diclofenac or naproxen, are a common choice.
NSAIDs can work well to ease the pain of osteoarthritis and reduce swelling in the joint. But sometimes they don’t help enough.
WHAT DID THE RESEARCHERS HOPE TO FIND?
In the new study, researchers wanted to find out whether adding an experimental pain medicine called tanezumab to an NSAID – diclofenac – might help. Tanezumab is given as an injection, while diclofenac is a tablet.
WHO WAS STUDIED?
The study included 604 people with osteoarthritis in their knee or hip who still had moderate to severe pain while taking diclofenac.
HOW WAS THE STUDY CONDUCTED?
The study participants were randomly chosen to have tanezumab injections or dummy (placebo) injections every eight weeks. Everyone in the study continued to take diclofenac. After 16 weeks, the researchers looked at the people’s scores on standard questionnaires measuring their pain, what they could do physically, and how much their osteoarthritis affected them overall. They compared these scores with those from the start of the study, to see whether people taking tanezumab plus diclofenac improved more than those taking diclofenac alone.
They also looked at what side effects people got. The researchers were particularly interested in whether people taking tanezumab plus diclofenac were more likely to get serious joint problems since earlier reports had linked tanezumab to a condition called osteonecrosis, which can cause severe joint damage requiring the
joint to be replaced.
WHAT DOES THE NEW STUDY SAY?
People taking tanezumab plus diclofenac had greater improvements on all the questionnaires, compared with people taking only diclofenac. However, those taking tanezumab plus diclofenac were more likely to report possible side effects, such as back pain, swelling in their legs, and odd sensations, such as tingling. They were
also more likely to stop their treatment because of side effects.
Overall, the chance of serious problems was similar for people taking tanezumab plus diclofenac and those taking diclofenac alone. However, six people taking both medicines were reported to have osteonecrosis, compared with no people taking only diclofenac. A follow-up review wasn’t able to confirm that the people actually
had this condition. However, one person was found to have osteoarthritis that was worsening quickly. An earlier study looking at the use of tanezumab with other NSAIDs had also reported this problem. Overall, the researchers concluded that the possible harms of taking tanezumab plus diclofenac outweighed the benefits.
HOW RELIABLE ARE THE FINDINGS?
This was a randomised controlled trial, which is the best type of study for finding out the effects of a treatment. Its results should be fairly reliable.
WHAT DOES THIS MEAN FOR ME?
If you have osteoarthritis in your knee or hip, you might have heard of tanezumab as a promising new treatment for osteoarthritis pain. Researchers are still exploring whether tanezumab is helpful for osteoarthritis when used on its own. But the findings from this study and others suggest that this treatment should not be used along with diclofenac and other NSAIDs.However, there are several other treatments you can try to improve your symptoms, including other medicines, pain-relieving creams, braces, and joint injections. Physiotherapy and especially regular exercise also can help, and surgery may be an option. Your doctor can help you decide what might be best for you.
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Date summary prepared: September 2014
Summary based on research article published on: 12 July 2013
Balanescu, A R et al. Efficacy and safety of tanezumab added on to diclofenac sustained release in patients with knee or hip osteoarthritis: a double-blind, placebo-controlled, parallel-group, multicentre phase III randomised clinical trial. Ann Rheum Dis 2014;73:1665-1672 doi:10.1136/annrheumdis-2012-203164
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