Rifampin is known to influence the pharmacokinetics of tofacitinib owing to drug interactions. The aim of this study was to determine the efficacy of tofacitinib on co-administration with rifampin in rheumatoid arthritis (RA) patients.

Biologic-naïve RA patients treated with tofacitinib were selected, and electronic medical reports were reviewed retrospectively. All patients underwent screening for latent tuberculosis infection (LTBI) before starting tofacitinib, and patients with positive results were treated to prevent progression to active tuberculosis. To evaluate the efficacy of tofacitinib with or without rifampin, the discontinuation rates of tofacitinib were examined during the first 6 months. Kaplan–Meier analysis was used to construct cumulative discontinuation curves, and comparisons were performed using the log-rank test.

Among 81 patients who starting tofacitinib, 21 were LTBI-positive and 18 were administered rifampin concomitantly with tofacitinib. Additionally, 14 of the 81 patients (17.3%) discontinued tofacitinib during the follow-up, and 7 patients discontinued tofacitinib because of uncontrolled RA activity. The discontinuation rates of tofacitinib within the first 6 months were significantly higher in patients treated with rifampin for LTBI than in those not treated with rifampin (lack of efficacy: 24.7% vs. 5.1%, P<0.01; all causes: 38.9% vs. 11.2%, P<0.01).

Discontinuation rates were higher in RA patients who started tofacitinib during chemoprophylaxis involving rifampin than in those who did not receive rifampin. Physicians should be aware that the efficacy of tofacitinib could be decreased by chemoprophylactic regimens for tuberculosis.