Study: Immunosuppressive Drug Helps With Rheumatoid Arthritis

Tacrolimus, an immunosuppressive drug primarily used to prevent organ rejection in transplant patients, appears to be effective in the treatment of rheumatoid arthritis in patients who are resistant to or cannot tolerate methotrexate, according to U.S. researchers.

Methotrexate works by altering the body's use of folic acid, which is needed for cell growth. Scientists believe that this interference with folic acid is an important reason for methotrexate's benefit in rheumatoid arthritis but the drug is not effective in all patients.

Researchers developed a study to determine the effectiveness, safety and optimal dose of tracrolimus in patients with rheumatoid arthritis.

The phase II, randomized, double-blind study was set in 12 community sites and 9 university-based sites. A total of 268 patients with rheumatoid arthritis who were resistant to or intolerant of methotrexate were randomized to receive treatment after discontinuing methotrexate.

A total of 141 patients completed the study. Participants were allowed to take nonsteroidal antiflammatory drugs and low doses of prednisone during the study. All of the patients were given 1, 3 or 5 mg of tacrolimus or a placebo once daily for 24 weeks. The results of the study were based on a 20 percent improvement and the status of tender and swollen joints at the end of treatment.

A 20 percent improvement was found in 15.5 percent of the patients receiving a placebo, 29 percent of those given 1 mg of tacrolimus, 34.4 percent of those given 3 mg of tacrolimus, and 50 percent of those given 5 mg of tacrolimus.

The tender joint count improved statistically significantly in all patients taking tacrolimus. The swollen joint count, physical function, and patient-assessed pain improved statistically significantly in the 3 mg and 5 mg groups.

Dropout rates were high (59 percent) and were more common for ineffectiveness in the group taking a placebo and toxicity in the tacrolimus groups. Discontinuation for creatinine elevation occurred in the 3 mg and 5 mg tacrolimus groups.

Researchers concluded that tacrolimus was effective in treating patients with rheumatoid arthritis who were resistant to methotrexate or could not tolerate the drug. The optimal dosage of tacrolimus appears to be more than 1 mg but less than 3 mg.

Other sources: Arthritis and Rheumatism