Background/Aim: High-dose methotrexate is a therapy for acute leukemia, malignant lymphoma, and osteosarcoma. Glycyrrhizin has been used to treat hepatic dysfunction caused by high-dose methotrexate. However, few studies have investigated the interaction between glycyrrhizin and high-dose methotrexate. Materials and Methods: Male Wistar rats were treated with high-dose methotrexate (500 or 1,000 mg/kg) alone, or with co-administration of 100 mg/kg glycyrrhizin. Plasma concentrations of methotrexate, alanine aminotransferase, aspartate aminotransferase, and total bilirubin were measured. Results: At both methotrexate doses, the blood concentration of methotrexate was significantly increased and total clearance was significantly reduced using co-administration of glycyrrhizin compared with methotrexate alone, which led to increased levels of hepatic enzymes. These results suggest that glycyrrhizin significantly increases the plasma level and delays the clearance of methotrexate, resulting in hepatic toxicity.
Conclusion: The concomitant use of methotrexate and glycyrrhizin should be considered with caution.Methotrexate is an antifolate drug that inhibits DNA synthesis and repair, and cellular replication (1, 2). High-dose methotrexate, defined as 500 mg/m 2 or higher administered intravenously, is used for a variety of cancer types, such as acute lymphoblastic leukemia, lymphoma, and osteosarcoma (3). However, high-dose methotrexate can cause a variety of toxic side-effects, including kidney injury, myelosuppression, mucositis, neurotoxicity and hepatotoxicity, which cause significant morbidity and delay treatment, leading to inferior anticancer outcomes (4). To prevent and mitigate toxicities, the serum concentrations of methotrexate and creatinine, and urine output are monitored, and supportive care is given, including intravenous hydration, urinary alkalinization, and rescue with leucovorin administration (5, 6). Recently, therapeutic drug monitoring has been implemented to reduce the side-effects of high-dose methotrexate by screening and managing its pharmacokinetics.Hepatic toxicity has a high incidence during high-dose methotrexate treatment, causing elevation in the levels of hepatic transaminases such as serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) (7-9). To treat hepatic toxicity, an increased dose of leucovorin, along with glycyrrhizin, is often administered. Glycyrrhizin has antiinflammatory and anti-allergy effects (10) and is widely used in the treatment of liver diseases to improve liver function, as well as in the treatment of other conditions, such as pruritus and urticaria (11,12).However, few studies have investigated the interaction between glycyrrhizin and methotrexate. It is important to elucidate drug interactions that may influence the efficacy and safety of high-dose methotrexate therapy. In particular, we considered the need for a basic study to reflect the clinical use of high-dose methotrexate therapy. Therefore, we evaluated the pharmacokinetic interactions ...