WASHINGTON (AP) -- A government advisory panel Tuesday recommended approval of the drug Actemra, promoted as a new type of treatment for rheumatoid arthritis, a painful and disabling swelling of the joints generally kept in check with medication.

The Hoffmann-La Roche, Inc. drug is already being used in Japan, and the Food and Drug Administration must now decide whether to give its approval for patients in the United States. Actemra's effectiveness was not in dispute, but some of its side effects raised questions. Nonetheless, the vote was 10-1 in favor of approval, and the agency generally follows the recommendations of its advisors.

While the most common form of arthritis comes from wear and tear on the joints as people age, rheumatoid arthritis is an immune system disorder in which the body turns on itself, attacking the joints. Known as "RA," it affects about 2.5 million Americans and usually strikes in early adulthood or middle age. Women are much more likely to suffer from the condition, which can lead to disability and an early death if untreated.

Actemra works by blocking the effect of a certain protein associated with inflammation. In clinical trials, patients with moderate to severe disease given Actemra showed an easing of symptoms and improvement on lab test results. One trial also showed that Actemra worked in some patients who had not seen improvement with a different type of treatment. In another trial, the drug was shown to help prevent damage to the joints.

But since Actemra acts to suppress the immune system, it can also have serious side effects. These can include severe infections, liver abnormalities and damage to digestive organs.

"It's always good to have new options for treating patients, but with a new drug, you don't know what the side-effect profile is," said Dr. Patience White, chief public health officer at the Arthritis Foundation. "In RA, you have a nearly 100 percent chance of being totally disabled and dying early, and you have a small chance of the side effects we're talking about." The group does not generally take a position on whether a medication should be approved.

The protein that Actemra acts on is known as IL-6 and serves as a chemical messenger between cells. Over-production of IL-6 has been linked to inflammation. Actemra, the only drug to act on this particular protein, blocks the interaction between IL-6 and cells. Actemra is not a chemical, but a type of biologic drug. It is an antibody genetically engineered in the lab.

New biologics are often among the more expensive medications on the market. Other biologic drugs for RA, including Enbrel, Humira and Remicade, act on a different protein related to inflammation. Patients would receive Actemra by intraveneous infusion every four weeks in their doctor's office.

Copyright 2008 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.