[A Survey of the Adverse Effects and Influence of Concomitant Drugs for Methotrexate Intrathecal Administration].

 In general, the intraventricular administration of cytotoxic antitumor drugs provides a high drug concentration in the cerebrospinal fluid with a reduced risk of systemic adverse reactions. Methotrexate (MTX) high-dose therapy requires close monitoring when performed in combination with trimethoprim-sulfamethoxazole (ST) therapy and proton pump inhibitor (PPI) and nonsteroidal anti-inflammatory drug administration for excretion delay and toxicity enhancement. While the frequency of systemic side effects is thought to be low with intrathecal administration, such effects do rarely but occasionally occur. We must consider drug interactions with combination therapy as a potential factor inducing such effects. We examined the patients who received MTX intrathecal administration at Fukuoka University Hospital from January 2013 to December 2014 with respect to the onset of side effects and combination therapy. MTX intrathecal administration was performed a total of 79 times in 27 patients. In five of these 27 patients, MTX intrathecal administration was performed twice a week, and hematotoxicity and non-hematotoxicity developed in two patients in whom ST was also administered. On the other hand, even if ST and/or PPI was administered, no side effects were observed in the patients administered levofolinate.