Objective. To determine the efficacy of minocycline in the treatment of rheumatoid arthritis (RA).

Methods. Minocycline (maximal oral daily dose 200 mg) or placebo was administered in a 26-week, randomized, double-blind study to 80 patients with active RA, who were treated or had previously been treated with at least one disease-modifying antirheumatic drug.

Results. There were 15 premature discontinuations: 6 (5 taking minocycline) because of adverse effects, 8 (all taking placebo) because of lack of efficacy, and 1 (taking placebo) because of intercurrent illness. There was a statistically significant improvement in the minocycline group over the placebo group. There was a pronounced improvement in laboratory parameters of disease activity; however, improvement in clinical parameters was less impressive. The observed adverse effects attributable to minocycline were mainly gastrointestinal symptoms and dizziness.

Conclusion. The results of the present study suggest that minocycline is beneficial and relatively safe in RA patients.