LONDON — A new type of anti-inflammatory painkiller is showing promise in experiments on people with arthritis in their knees.
Research presented at a conference in Stockholm this week indicated the drug works just as well for arthritis as traditional nonsteroidal anti-inflammatory drugs such as aspirin and ibuprofen, but is gentler on the stomach.
Experts say the medication, licofelone, could offer an alternative to newer arthritis drugs, such as Vioxx and Celebrex, which have recently come under suspicion of increasing certain people's heart risks.
Licofelone, being developed by German pharmaceutical manufacturer Merckle, works in a slightly different way from other anti-inflammatory painkillers, and some scientists suspect it might have benefits beyond pain relief.
"It's extremely encouraging and it will provide another option for treatment for arthritis patients, which we desperately need," said Dr. Jean-Pierre Pelletier, head of the osteoarthritis research unit at the University of Montreal's Central Hospital, who was not connected with the research.
Conventional nonsteroidal anti-inflammatories work by shutting off production of prostaglandins, inflammation-causing substances. They do this by blocking the action of the enzyme cox, which produces prostaglandins.
In the late 1980s, scientists discovered there were two varieties of the cox enzyme. They found that while cox-2 causes pain and inflammation as part of the body's repair process, cox-1 protects the lining of the stomach.
That explained why the painkillers caused stomach upsets. The discovery led to drugs designed to relieve pain but spare the stomach.
That type of pill, including Vioxx and Celebrex, blocks only cox-2 rather than both cox enzymes, and is known as a cox-2 inhibitor.
However, recent studies have suggested that some cox-2 blockers might increase the risk of blood clots.
Scientists speculate it may be because the two cox enzymes are out of balance. As well as protecting the stomach lining, cox-1 plays a role in blood clotting.
The new drug, licofelone, blocks both cox-1 and cox-2, like the older painkillers, but also interferes with the action of another enzyme involved in pain and inflammation, called 5-lox.
The study, presented at the European Congress of Rheumatology in Stockholm, found that licofelone worked as well as the older drugs, was gentle on the stomach and showed no trace of side effects that could cause heart problems.
It involved 710 people with arthritic knees, followed for a year.
One-third received a low dose of the new drug, one-third a high dose and the others got naproxen, a conventional nonsteroidal anti-inflammatory.
The study's lead investigator, Dr. Jean-Yves Reginster of the University of Liege, said the new drug was as effective as the old one. In each of the three arms of the study, two-thirds of the patients had significant improvements in pain and inflammation.
Those on the new drug were 80 percent less likely than the others to get a stomach ulcer.
Reginster said the study did not directly address heart safety, but that swelling in the feet and ankles, and elevated blood pressure — both side effects suggested in studies of cox-2 blockers — did not affect patients taking the new drug.
Pelletier said he doesn't expect to see any heart problems with the new drug because its cox-enzyme-blocking action is balanced.
The fact that the new drug also blocks the enzyme 5-lox may give it extra appeal, Pelletier added.
There is preliminary evidence that 5-lox may play a role in deterioration of the joints, and licofelone is being investigated as a possible disease-slowing drug, he said.
On the Net: European Congress of Rheumatology, www.eular.org/eular2002/index.cfm