Search

The monolithic type (Mo type) of tablet, where the drug is uniformly dispersed in a tablet, causes drug release in gastric juice with an initial burst. In order to suppress this drug release, we prepared a sandwiched type tablet (Sw type) where the drug layer is put between the layers of a mixed powder of sodium alginate (Al) and methyl glycol chitosan (MG). We then studied the release action based on the difference in tablet structure using theophylline (TH) as the model drug. The amount of TH released from the tablet was measured by absorptiometry (271 nm) upon transferring the tablet from artificial gastric juice (pH 1.2) to artificial intestinal juice (pH 6.8) after a given time. When the tablet was transferred from artificial gastric juice to artificial intestinal juice, the ‘squeezing effect’, in which the release rate rapidly increases, was observed. The release rate increased 1.9 times in the Mo type and 11 times in the Sw type. As a result, the drug release rate in gastric juice could be effectively restrained down to approximately 10% by using the Sw type tablet structure. [ABSTRACT FROM AUTHOR]

The compatibility of artificial materials with living system, such as antithrombogenicity and antiimmunogenicity, has been an important issue in the field of the biomaterials researches at the early periods of the biomaterials research. After that, the bioabsorbable materials have been subsequently incorporated as biomaterials. As a result, biomaterial researchers started participating in the field of drug delivery system (DDS), and combining biomaterials and cells not only led to bioartificial organs, but also tissue engineering. The bioabsorbable biomaterials function as scaffolds for the cells and play an important role in the field of regenerative medicine researches. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 930-932, 2019., (© 2019 Wiley Periodicals, Inc.)

This review reflects back over almost 40 years of the author's basic research conducted at Graduate School of Pharmaceutical Sciences, Osaka University, Japan. After performing postdoctoral research in USA, the author became a research associate at Prof. Yoshiharu Miura's lab and started research on Biochemical Engineering in 1984. At that time, the main research purpose was to solve global environmental issues for maintaining human health. The author's achievements included novel useful material production system under inorganic conditions and genetically engineered whole-cell bacterial sensors detecting arsenite by naked eye without a detecting device. Another theme in the lab was to construct bioartificial liver support system. Various scaffolds for hepatocytes were newly prepared for constructing the compact reactor. Besides the bioreactor study, the author conducted cell transplantation research for the treatment of chronic liver diseases. It was shown that mesenchymal stem cells derived from third molars (wisdom teeth) could differentiate into hepatocytes and exhibit therapeutic effects in liver-damaged animals. After 2006, the lab started research on drug delivery systems, including noninvasive delivery of drugs such as peptides and nucleic acids by regulating epithelial tight junctions. Many substances enabling drug delivery through "paracellular" route were newly prepared. The author started basic research on Biochemical Engineering in the 1970s. Although these studies eventually shifted into the pharmaceutical field, the underlying concept was based on "engineering" throughout a 40-year research period. The author cordially thanks all colleagues for supporting engineering research in our lab.

Neutron capture therapy (NCT) is a promising non-invasive cancer therapy approach and some recent NCT research has focused on using compounds containing gadolinium as an alternative to currently used boron-10 considering several advantages that gadolinium offers compared to those of boron. In this study, we evaluated gadolinium-entrapped liposome compound as neutron capture therapy agent by in vivo experiment on colon-26 tumor-bearing mice. Gadolinium compound were injected intravenously via tail vein and allowed to accumulate into tumor site. Tumor samples were taken for quantitative analysis by ICP-MS at 2, 12, and 24 h after gadolinium compound injection. Highest gadolinium concentration was observed at about 2 h after gadolinium compound injection with an average of 40.3 μg/g of wet tumor tissue. We performed neutron irradiation at JRR-4 reactor facility of Japan Atomic Energy Research Institute in Tokaimura with average neutron fluence of 2×10¹² n/cm². The experimental results showed that the tumor growth suppression of gadolinium-injected irradiated group was revealed until about four times higher compared to the control group, and no significant weight loss were observed after treatment suggesting low systemic toxicity of this compound. The gadolinium-entrapped liposome will become one of the candidates for Gd delivery system on NCT., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)