Rheumatoid arthritis (RA) is the most common inflammatory form of arthritis. It is a systemic autoimmune driven process that affects more than 2 million Americans.
While disease-modifying anti-rheumatic drugs (DMARDS) were our stalwarts through the 1980's and early 1990's, biologic drugs, specifically TNF inhibitors, have changed our whole way of looking at the treatment of rheumatoid arthritis.
Using these drugs in combination with DMARDS, it has been possible to induce remission in many patients with RA.
TNF inhibitors block the effects of tumor necrosis factor (TNF), a protein messenger that drives the autoimmune process that causes the destructive potential of RA.
There are five TNF inhibitors that have been approved by the FDA. The first is Enbrel. This is a fusion protein with a receptor that binds to circulating TNF in the blood. By acting like a sponge it reduces the signs and symptoms of RA. It is generally best when used in combination with methotrexate. The drug is given by subcutaneous injection weekly.
Humira is a totally human monoclonal antibody directed against TNF. It also appears to be more effective when used in combination with methotrexate. It is administered by subcutaneous injection every two weeks.
Remicade is a chimeric antibody, meaning it's part human and part mouse. It's directed against TNF and also works best when given along with methotrexate. It is the only TNF inhibitor which is administered by intravenous infusion. Remicade can be given as often as every four to eight weeks.
Cimzia is a PEGylated TNF inhibitor. The pegylation keeps the drug around longer in the synovial tissue (joint lining). It's also given by subcutaneous injection once every two weeks.
Simponi is a human monoclonal antibody directed against TNF. It is given as a subcutaneous injection once a month.
Generally if a patient hasn't responded within twelve weeks, they are probably not going to respond. Also, some people respond initially but then begin to lose their response.
Patients who don't respond to one TNF inhibitor can be tried on another since some people respond to one and not the other.
There are many potential side effects that must be considered in patients treated with TNF inhibitors.
These include increased susceptibility to various infections, neurologic disorders, possible increased susceptibility to certain malignancies such as lymphoma, and many others. A much more in-depth discussion of potential risk factors is available on each manufacturer's website. Close observation and monitoring of patients taking these potent medicines is mandatory.