Optimal Administration of Glycyrrhizin Avoids Pharmacokinetic Interactions With High-dose Methotrexate and Exerts a Hepatoprotective Effect.

BACKGROUND/AIM: Glycyrrhizin (GZ) is widely used to treat high-dose methotrexate (MTX)-induced liver dysfunction. However, in a previous in vivo study, we showed that simultaneous administration of both drugs increased the plasma concentration of MTX and exacerbated hepatic injuries. In this study, we investigated the optimal dosing interval in rats to avoid the interaction between high-dose MTX and GZ and to demonstrate the inherent hepatoprotective effect of GZ. MATERIALS AND METHODS: Male Wistar rats were treated with high-dose MTX (2,000 mg/kg) alone, with concomitant administration of 100 mg/kg GZ or GZ administered 3, 6, and 24 h before MTX administration. Plasma concentrations of MTX, alanine aminotransferase, aspartate aminotransferase, and total bilirubin were measured. RESULTS: The plasma concentration and half-life of methotrexate were significantly increased after concomitant administration of GZ, or when GZ was administered 3 h before MTX administration, compared with MTX alone, increasing hepatic enzyme levels. However, when GZ was administered 6 and 24 h before MTX administration, the levels were not significantly different from those of MTX alone and showed a tendency to decrease MTX-induced liver injury. These results suggest that the pharmacokinetic interaction between GZ and MTX could be avoided and the hepatoprotective effect of GZ could be achieved by an optimal dosing regimen, using the half-life of GZ as an indicator. CONCLUSION: When using high-dose MTX in combination with GZ, the administration intervals should be considered to avoid unwanted interactions and to achieve the GZ hepatoprotective effect.

Paliperidone-Induced Acute Hyperglycemia Is Caused by Adrenaline Secretion via the Activation of Hypothalamic AMP-Activated Protein Kinase.

Although paliperidone-related hyperglycemia has been extensively examined, the underlying mechanisms have not yet been elucidated. We investigated the effects of a single intravenous injection of paliperidone (0.2, 0.4, or 0.6 mg/kg) on serum concentrations of glucose and other endogenous metabolites in rats. We also examined the effects of a single intravenous injection of paliperidone (0.4 mg/kg) on AMP-activated protein kinase (AMPK) activity in the hypothalamus and liver. To clarify the relationship between AMPK activity and adrenaline secretion, the effects of berberine, which inhibits hypothalamic AMPK, on paliperidone-induced hyperglycemia were assessed. Significant increases were observed in serum glucose, adrenaline, and insulin concentrations following intravenous injections of paliperidone at doses of 0.4 and 0.6 mg/kg. A propranolol pretreatment attenuated paliperidone-induced increases in serum concentrations of glucose, but not adrenaline. Significant increases were also noted in phosphorylated AMPK concentrations in the hypothalamus following the administration of paliperidone at a dose of 0.4 mg/kg. A berberine pretreatment attenuated paliperidone-induced increases in blood concentrations of glucose, adrenaline, and insulin and phosphorylated AMPK concentrations in the hypothalamus. Collectively, the present results demonstrated that an acute treatment with paliperidone induced hyperglycemia, which was associated with the effects of hypothalamic AMPK activation on the secretion of adrenaline.

Risk Factors for Hepatic Toxicity of High-dose Methotrexate in Patients With Osteosarcoma.

BACKGROUND/AIM: High-dose methotrexate (HD-MTX) is widely used to treat osteosarcoma. However, some patients develop hepatic toxicity, leading to dose modification and delays in the scheduled chemotherapy. The present study aimed to identify the risk factors of hepatotoxicity in patients with osteosarcoma. PATIENTS AND METHODS: We conducted a retrospective study of patients with osteosarcoma treated with HD-MTX between January 2014 and June 2020 at the National Cancer Center Hospital, Japan. The risk factors for MTX-induced hepatotoxicity (≥grade 3) were identified using multivariate logistic regression analysis. RESULTS: The final analysis included 88 courses of 36 patients. Hepatotoxicity occurred in 51 (58.0%) of the 88 courses. Female sex, MTX dose (>10.2 g/m2), and serum calcium concentration (>9.3 mg/dl) were identified as risk factors for HD-MTX-induced hepatotoxicity. CONCLUSION: Identifying the risk factors of HD-MTX-induced hepatotoxicity may contribute to improvements in the safety and management of HD-MTX therapy.

Concomitant Use of High-dose Methotrexate and Glycyrrhizin Affects Pharmacokinetics of Methotrexate, Resulting in Hepatic Toxicity.

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.

Tolerogenic properties of CD206+ macrophages appeared in the sublingual mucosa after repeated antigen-painting.

The sublingual mucosa (SLM) in the oral cavity is utilized as the site for sublingual immunotherapy to induce tolerance against allergens. We previously reported that CD206+ round-type macrophage-like cells were induced in the SLM after repeated antigen (e.g. cedar pollen or fluorescein isothiocyanate (FITC))-painting. In this study, we examined the phenotypic and functional properties of CD206+ cells induced by repeated FITC-painting on the SLM. CD206+ cells after the repeated FITC-painting possessed a macrophage-like CD11b+Ly6C+ F4/80+CD64+ phenotype and expressed TIM-4, which was expressed in tolerogenic tissue-resident macrophages, at a high level. SLM CD206+ cells preferentially expressed molecules related to endocytosis and homeostatic processes, including the novel B7 family of immune checkpoint molecules, as assessed by microarray analyses. SLM CD206+ cells showed preferential expression of M2-related genes such as Fizz1, Aldh1a1 and Aldh1a2 but not Ym-1 and Arginase-1. A CD206+ cell-rich status inhibited OVA-specific CD4+ T-cell responses but reciprocally enhanced the proportion of both IL-10+CD4+ cells and Foxp3+ regulatory T-cells in regional lymph nodes. Co-culture of CD206+ cells with dendritic cells (DCs) showed that IL-12 production was suppressed in DCs concurrent with the decline of the MHC class IIhiCD86+ population, which was restored by neutralization of IL-10. These results demonstrate SLM CD206+ cells show the feature of tolerogenic macrophages and down-regulate the antigen-presenting cell function of mature DCs resulting in the inhibition of CD4+ T-cell responses.

Inhibitory effects of fruit juices on cytochrome P450 2C9 activity in vitro.

There is limited information on the effect of fruits on human cytochrome P450 (CYP) 2C9 activity. The objective of this study was to determine the effect of fruit juice on CYP2C9-mediated drug metabolism. Nine citrus fruits and eight tropical fruits were chosen. We investigated effects of the fruits on diclofenac 4'-hydroxylation and tolbutamide hydroxylation by human liver microsomes. Among the fruits, pineapple juice showed potent inhibition of CYP2C9 activity. The addition of 25 microl (5.0% v/v) of pineapple juice resulted in almost complete inhibition. Next we examined the inhibitory effect of bromelain, a cysteine protease in pineapple. Bromelain also strongly inhibited CYP2C9 activity. In addition, E-64, a cysteine protease inhibitor, almost entirely blocked inhibition by pineapple juice and bromelain. Thus we found that pineapple juice was a potent inhibitor of CYP2C9, and that the inhibitory effect might be due to the bromelain contained in pineapple.