Reactive metabolite of trovafloxacin activates inflammasomes: Implications for trovafloxacin-induced liver injury.

Trovafloxacin is a quinolone antibiotic drug with broad-spectrum activity, which was withdrawn from a global market relatively soon after approval because of serious liver injury. The characteristics of trovafloxacin-induced liver injury are consistent with an idiosyncratic reaction; however, the details of the mechanism have not been elucidated. We examined whether trovafloxacin induces the release of damage-associated molecular patterns (DAMPs) that activate inflammasomes. We also tested ciprofloxacin, levofloxacin, gatifloxacin, and grepafloxacin for their ability to activate inflammasomes. Drug bioactivation was performed with human hepatocarcinoma functional liver cell-4 (FLC-4) cells, and THP-1 cells (human monocyte cell line) were used for the detection of inflammasome activation. The supernatant from the incubation of trovafloxacin with FLC-4 cells for 7 days increased caspase-1 activity and production of IL-1ß by THP-1 cells. In the supernatant of FLC-4 cells that had been incubated with trovafloxacin, heat shock protein (HSP) 40 was significantly increased. Addition of a cytochrome P450 inhibitor to the FLC-4 cells prevented the release of HSP40 from the FLC-4 cells and inflammasome activation in THP-1 cells by the FLC-4 supernatant. These results suggest that reactive metabolites of trovafloxacin can cause the release of DAMPs from hepatocytes that can activate inflammasomes. Inflammasome activation may be an important step in the activation of the immune system by trovafloxacin, which, in some patients, can cause immune-related liver injury.

Study on enteral nutrient components causing decreased gastric phenytoin absorption.

BACKGROUND: Previously, we revealed that coadministration of particular enteral nutrients (ENs) decreases plasma concentrations and gastric absorption of phenytoin (PHT), an antiepileptic drug, in rats; however, the mechanism has not been clarified. METHODS: We measured the permeability rate of PHT using a Caco-2 cell monolayer as a human intestinal absorption model with casein, soy protein, simulated gastrointestinal digested casein protein (G-casein or P-casein) or simulated gastrointestinal digested soy protein (G-soy or P-soy), dextrin, sucrose, degraded guar gum, indigestible dextrin, calcium, and magnesium, which are abundant in the ENs, and measured the solution's properties. RESULTS: We demonstrated that casein (40 mg/ml), G-soy or P-soy (10 mg/ml), and dextrin (100 mg/ml) significantly decreased the permeability rate of PHT compared with the control. By contrast, G-casein or P-casein significantly increased the permeability rate of PHT. We also found that the PHT binding rate to casein 40 mg/ml was 90%. Furthermore, casein 40 mg/ml and dextrin 100 mg/ml have high viscosity. Moreover, G-casein and P-casein significantly decreased the transepithelial electrical resistance of Caco-2 cell monolayers compared with casein and the control. CONCLUSION: Casein, digested soy protein, and dextrin decreased the gastric absorption of PHT. However, digested casein decreased PHT absorption by reducing the strength of tight junctions. The composition of ENs may affect the absorption of PHT differently, and these findings would aid in the selection of ENs for orally administered PHT.

Liquid Enteral Nutrients Alter the Pharmacokinetics of Orally Administered Carbamazepine in Rats.

The interaction between enteral nutrients (ENs) and drugs co-administered through a nasogastric (NG) tube reportedly affects the absorption and resultant plasma concentrations of the respective drugs. However, the gastrointestinal absorption of carbamazepine (CBZ), an antiepileptic drug, co-administered with liquid ENs through an NG tube has not been clarified. In this study, we measured the recovery rate (%) of CBZ (Tegretol® powder) passed through an NG tube when co-administered with distilled water or ENs (F2α®, Racol® NF, Ensure Liquid®, and Renalen® LP) of different compositions, frequently used in Japan. We also measured the plasma CBZ level in 26 rats after oral co-administration of CBZ with liquid ENs. The CBZ recovery rate was close to 100% in rats of all EN groups after passage through the NG tube. Furthermore, CBZ area under the plasma concentration-time curve from time zero to 9 h (AUC0→9h) of the Ensure liquid® group decreased compared with that of control group (P < 0.05) and Renalen® LP group (P < 0.01). However, the AUC0→9h of CBZ remained unchanged when co-administered with Ensure liquid® 2 h after initial CBZ administration. In conclusion, the co-administration of CBZ with Ensure Liquid® caused a reduction in the absorption of CBZ from the gastrointestinal tract, without adsorption on the NG tube. The administration of Ensure Liquid® 2 h after CBZ is a way to prevent a decrease in plasma CBZ concentration. Our findings suggest that carefully monitoring the plasma levels of CBZ is necessary in co-administation with Ensure liquid® to prevent the unintended effects of the interaction between CBZ and liquid EN.

Is cyclosporine A transport inhibited by pravastatin via multidrug resistant protein 2?

BACKGROUND AND PURPOSE: Cyclosporine A (CyA) is an immunosuppressant drug used to treat various autoimmune diseases and transplantations. It has been reported that, in humans, CyA is metabolized by cytochrome P450 (CYP) 3A or excreted by P-glycoprotein/multidrug resistant protein (MRP) 2. Pravastatin, a statin, is used to treat hyperlipidemia and has also been reported to be excreted primarily by MRP2. We observed an increased blood CyA level in a patient following pravastatin administration, suggesting the possibility that CyA interacted with the pravastatin via MRP2. The aim of the study reported here was to investigate the effects of pravastation on CyA transport via MRP2 using a human colon adenocarcinoma (Caco-2) monolayer model system. METHODS: Calcein, a substrate of MRP families, was first added to the tissue culture medium of the Caco-2 cells, and CyA (5, 50 microM) and pravastatin (0.1, 1.0 mM) were then added to the apical and basolateral sides. After a 30-min incubation, calcein was effluxed from the Caco-2 cells and the level in the culture medium was assayed. CyA was then added to the tissue culture medium of the Caco-2 cells, and pravastatin (0.1, 0.5, 1.0 mM) was added to the apical and basolateral sides. After a 30-min incubation, CyA was effluxed from the Caco-2 cells, and the level in the culture medium was assayed. RESULTS: The calcein efflux to the apical side was decreased significantly by the addition of pravastatin (1.0 mM) and CyA (5, 50 microM), respectively. The CyA efflux to the apical side was decreased significantly by the addition of pravastatin (1.0 mM). CONCLUSIONS: Based on these results, we suggest that CyA transport may be competitively inhibited by pravastatin via MRP2.