Inhibitory effect of ezetimibe can be prevented by an administration interval of 4 h between alpha-tocopherol and ezetimibe

Tocopherol is used not only as an ethical drug but also as a supplement. In 2008, it was reported that alpha-tocopherol is partly transported via an intestinal cholesterol transporter, Niemann-Pick C1-Like 1 (NPC1L1). Ezetimibe, a selective inhibitor of NPC1L1, is administered for a long time to inhibit cholesterol absorption and there is a possibility that the absorption of alpha-tocopherol is also inhibited by ezetimibe. This study investigated the influence of ezetimibe on the absorption of alpha-tocopherol with single administration and long-term administration. An approach to avoid its undesirable consequence was also examined. alpha-Tocopherol (10 mg/kg) and ezetimibe (0.1 mg/kg) were administered to rats, and the plasma concentration profiles of alpha-tocopherol and tissue concentrations were investigated. The plasma concentration of alpha-tocopherol was decreased by the combination use of ezetimibe in the case of concurrent single administration. On the other hand, inhibition of the absorption of alpha-tocopherol was prevented by an administration interval of 4 h. In a group of rats administered for 2 months with a 4 h interval, not only the plasma concentration but also the liver concentration was increased compared with those in a group with concurrent combination intake of alpha-tocopherol and ezetimibe. The absorption of alpha-tocopherol was inhibited by ezetimibe. The inhibitory effect of ezetimibe can be prevented by an administration interval of 4 h, although ezetimibe is a medicine of enterohepatic circulation. Attention should be paid to the use of ezetimibe and components of NPC1L1 substrates such as alpha-tocopherol. Copyright (C) 2016 John Wiley & Sons, Ltd

Transport via Niemann-Pick C1 Like 1 contributes to the intestinal absorption of ubiquinone

Ubiquinone, which is a component in the electron-transport systems of mitochondria, is essential for various activities related to energy metabolism, but the detailed absorption mechanism of ubiquinone is not clear. On the other hand, Niemann-Pick C1 Like 1 (NPC1L1) is involved in the intestinal absorption of fat-soluble components such as cholesterol. In this study, we investigated whether the intestinal absorption of ubiquinone was transported by NPC1L1 as is cholesterol. In this study, coenzyme q10 (CoQ10) and coenzyme q9 (CoQ9) were used as models of ubiquinone. The transport activity of ubiquinone was increased significantly in NPC1L1-overexpressed Madin-Darby canine kidney (MDCK) cells compared with that in pMAM2-BSD vector-transfected MDCK cells and the uptake of ubiquinone was decreased in the presence of ezetimibe, an inhibitor of NPC1L1. These results indicate that NPC1L1 mediates the transport of ubiquinone. Furthermore, to clarify the effect of NPC1L1 on the intestinal absorption of CoQ10, emulsified CoQ10 was orally administered to Wistar rats, and the plasma concentration was measured. The plasma concentration of CoQ10 was significantly decreased by coadministration of ezetimibe and CoQ10 compared to that with administration of only CoQ10. This result indicates that the intestinal absorption of CoQ10 is mediated by NPC1L1. (C) 2020 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved

Usefulness of the Albumin-Bilirubin Score in Determining the Initial Dose of Voriconazole for Patients with Liver Cirrhosis

The Child-Pugh score is widely used to assess liver function and estimate drug clearance in patients with liver cirrhosis. Recently, the albumin-bilirubin (ALBI) score, which objectively assesses liver function based only on albumin and total bilirubin levels, was developed as a new method. The purpose of this study was to analyze the relationship between the liver function assessment method and the plasma concentration of voriconazole (VRCZ), an antifungal drug for patients with liver cirrhosis. This single-center retrospective study enrolled 159 patients who received VRCZ between 2012 and 2020. In patients administered VRCZ orally, the median concentration to dose (C : D) ratio increased with the progression of Child-Pugh and ALBI grades. Positive correlations between the ALBI score and VRCZ C : D ratio were observed in patients with cirrhosis (r = 0.52 (95% confidence interval, 0.069-0.79); p < 0.05). In addition, a highly negative correlation was observed between the ALBI score and VRCZ daily maintenance dose (r=-0.79 (95% confidence interval, -0.92 to -0.50); p < 0.0001). In contrast, for patients administered VRCZ intravenously, no increase in C : D ratio was observed for both Child-Pugh and ALBI scores compared to the non-liver cirrhosis group. This may be because the injection is often used in severely ill patients, and factors other than impaired liver function may affect the plasma concentrations of VRCZ. In conclusion, the ALBI score was shown to be useful in predicting VRCZ clearance as well as the Child-Pugh score, and the initial dose of VRCZ might be determined according to the ALBI score

Enhancement of lymphatic transport of lutein by oral administration of a solid dispersion and a self-microemulsifying drug delivery system.

Lutein is located in the macula lutea in the human eye. Since humans cannot synthesize lutein de novo, it must be digested as food. Some studies including our previous study showed very low absorption of lutein after oral administration. These studies also suggested that the absorption route of lutein from the small intestine involves not only the blood but also the lymph. The aim of this study was to clarify the transfer of lutein into lymph and the tissue distribution after oral administration of a solid dispersion (SD) and a self-microemulsifying drug delivery system (SMEDDS) for improvement of the absorption. We used thoracic lymph-cannulated rats. It was shown that the plasma concentrations of lutein in the SD and SMEDDS groups were increased compared with that in the powder group. The absorption of lutein after oral administration of each formulation was clearly evaluated by its cumulative amount in lymph. Our data clearly showed that lutein is transferred into the lymph stream from the small intestine

A new system to evaluate characteristics of Niemann-Pick C1 Like 1-mediated cholesterol transport using Xenopus laevis oocytes

Niemann-Pick C1 Like 1 (NPC1L1) is known to be involved in the intestinal absorption of cholesterol. For evaluating the function of NPC1L1, cell lines such as Caco-2, Madin-Darby canine kidney (MDCK) II, and McA-RH7777 have been used in previous studies, but the detailed molecular mechanism of transport has not been elucidated. In this study, the characteristics of cholesterol transport via NPC1L1 were investigated using a Xenopus laevis oocyte expression system in addition to a conventional cell line with stable expression. The transport activity of cholesterol uptake was increased in NPC1L1-overexpressed MDCK cells compared with that in mock cells, but MDCK cells expressed endogenous NPC1L1 and had high cholesterol transport activity. On the other hand, cRNA-injected oocytes expressed NPC1L1 after culturing for 5-6 days. The transport activity of cholesterol uptake was increased in NPC1L1 cRNA-injected oocytes compared with that in water-injected oocytes. In addition, the uptake of cholesterol was decreased in the presence of ezetimibe, an NPC1L1 inhibitor, in cRNA-injected oocytes but not in control oocytes, indicating that endogenous NPC1L1 is not expressed in oocytes. Furthermore, cholesterol uptake was substantially decreased in NPC1L1 L216A cRNA-injected oocytes compared with that in NPC1L1 cRNA-injected oo-cytes, indicating that leucine at position 216 of NPC1L1 is important for cholesterol transport and that an oocyte expression system is useful for mutant analysis. These results indicate that the oocyte expression system is useful for evaluating the characteristics of NPC1L1-mediated cholesterol transport and may contribute to the elucidation of the detailed molecular mechanism of cholesterol transport via NPC1L1

Monitoring Salivary Concentrations of Tedizolid and Linezolid Using Rats

Background and ObjectiveTherapeutic drug monitoring (TDM) is an effective tool for the management of patients who are administered linezolid. The use of saliva for TDM has potential advantages over the use of plasma; however, only a few reports have compared drug concentrations in the saliva and plasma. Moreover, there are no reports on the salivary concentration of tedizolid, an oxazolidinone antibiotic similar to linezolid. In the present study, the concentrations of tedizolid and linezolid in rat submandibular saliva were compared with those measured in the plasma.MethodsTedizolid (10 mg/kg, n = 6) and linezolid (12 mg/kg, n = 5) were administered via the rat tail vein. Submandibular saliva and plasma samples were collected for up to 8 h after the initiation of drug administration, and assayed for the concentrations of tedizolid and linezolid.ResultsA strong correlation was found between the saliva and plasma concentrations of tedizolid (r = 0.964, p < 0.001) and linezolid (r = 0.936, p < 0.001). The value of tedizolid maximum concentration of drug (C-max) was 0.99 & PLUSMN; 0.08 & mu;g/mL in the saliva and 14.46 & PLUSMN; 1.71 & mu;g/mL in the plasma. Meanwhile, the C-max of linezolid was 8.01 & PLUSMN; 1.42 & mu;g/mL in the saliva and 13.00 & PLUSMN; 1.90 & mu;g/mL in the plasma. According to these results, the saliva/plasma concentration ratios of tedizolid and linezolid in rats were 0.0513 & PLUSMN; 0.0080 and 0.6341 & PLUSMN; 0.0339, respectively.ConclusionsConsidering the correlation between saliva and plasma concentrations of tedizolid and linezolid, as well as the characteristics of saliva, the results of this study suggest that saliva is a useful matrix for TDM