Clinical

Methotrexate and isoniazid safe in rheumatoid arthritis patients with TB

Last Updated: 2008-04-16 17:14:27 -0400 (Reuters Health)

By David Douglas

NEW YORK (Reuters Health) - In patients on methotrexate for rheumatoid arthritis (RA), concomitant treatment with isoniazid for latent or active TB appears to be well tolerated, researchers report in the April issue of the Annals of the Rheumatic Diseases.

This is of particular importance, senior investigator Dr. Pamela B. Rosenthal told Reuters Health, in light of the possible reactivation of TB with tumor necrosis factor blockers. "The potentially devastating consequences of an active TB infection are of heightened concern to physicians, who prescribe anti-tumor necrosis factor medications, and patients alike."

Dr. Rosenthal of New York University School of Medicine, New York and colleagues point out that both methotrexate and isoniazid are potentially hepatotoxic and data on combined treatment are lacking.

The researchers sought to examine the safety of isoniazid therapy in RA patients on methotrexate, before initiation of the tumor necrosis factor antagonist therapy.

The team retrospectively studied data on 44 patients who were concomitantly treated with methotrexate for RA and isoniazid for active or latent TB. All had normal liver function test results at baseline.

Transient increases in liver function tests were seen in 11% of the patients, but these did not go beyond twice the upper limit of normal values and all resolved spontaneously.

Among the patients who went on to treatment with etanercept or adalimumab, no reactivation of TB was observed.

The researchers conclude that the additive risk of hepatotoxicity with isoniazid added to methotrexate is low, but nonetheless, they stress that "it is prudent to follow liver function tests closely" in patients taking this combination.

Ann Rheum Dis 2008;67:462-465.