Prophylactic trimethoprim-sulfamethoxazole is safe in adult patients with primary central nervous system lymphoma receiving high-dose methotrexate.

This retrospective study investigated the potential drug-drug interactions between trimethoprim-sulfamethoxazole (TMP-SMZ) and high-dose methotrexate (HD-MTX) in adult patients with primary central nervous system lymphoma (PCNSL). A total of 143 Chinese adult patients with PCNSL who received 498 cycles of MTX were included. Differences in the pharmacokinetics of MTX, including C, clearance (CL) and AUC with and without co-administration of TMP-SMZ were assessed. The incidence of MTX-related acute kidney injury (AKI), hepatotoxicity, myelosuppression, and delayed MTX elimination at 48 and 72 h were also compared. Patients were divided into two cohorts for analysis: 146 cycles with TMP-SMZ exposure and 352 cycles without TMP-SMZ exposure. Patients who received TMP-SMZ concurrently with HD-MTX exhibited a 1.13-fold increase in C, a 1.12-fold increase in AUC and a reduction in CL by 0.87-fold for MTX. There was no significant difference in the incidence of MTX-related AKI, hepatotoxicity, myelosuppression, or delayed MTX elimination between the two cohorts. Prophylactic TMP-SMZ might lead to increased MTX exposure but has no impact on the incidence of myelosuppression, AKI, and hepatotoxicity. These results suggested that prophylactic TMP-SMZ is safe for adult patients with PCNSL receiving HD-MTX.