Federal regulators recently approved Pfizer’s new Xeljanz treatment for rheumatoid arthritis. Xeljanz was approved for patients with moderate to severe rheumatoid arthritis who did not benefit from the oral treatment methotrexate. Xeljanz can be used with methotrexate and certain other treatments. Industry analysts have predicted the new drug, also known as tofacitinib, could grow to sales of $3 billion annually. Xeljanz is taken in 5-milligram pills twice daily.  About 1.3 million people in the United States suffer from rheumatoid arthritis, which can cause problems in wound healing.