Paricalcitol, a synthetic vitamin D analog: a candidate for combination therapy with biological agents in rheumatoid arthritis.

Biologic agents, especially TNFα inhibitors, appear to be very effective in treatment of rheumatoid arthritis (RA). Although the use of biologic agents has greatly improved the therapeutic efficacy in management of RA, biologic therapies for RA treatment have several limitations. These agents fail to achieve complete remission in substantial portion of RA patients. Also certain adverse events have been observed, including serious bacterial infections and reactivation of latent tuberculosis. Previous reports demonstrated that TNFα inhibitors are more efficacious in combination with other drugs such as methotrexate. In this report, we suggest that paricalcitol, a synthetic vitamin D analog is another candidate molecule for combination therapy with TNFα inhibitors in RA.