Layered double hydroxides (LDHs) have been used commercially as antacids, to stabilize drugs, to allow the controlled release of incorporated drugs, and to act as drug carriers to reduce drug accumulation within the body. Several types of LDH were investigated: nitrate type (LDH-NO 3 ); chloride type (LDH-Cl); and carbonate type (LDH-CO 3 ). Each type was added to an aqueous or methanol (MeOH) solution containing a drug (pravastatin or nateglinide). With pravastatin sodium, the interlayer distance expanded after reaction with LDH-NO 3 and LDH-Cl in aqueous solution. In contrast, the interlayer distance of LDH-CO 3 increased in methanol with nateglinide. Each drug was intercalated into the interlayer space of LDH by ion exchange. The hygroscopicity of the drug substances, complexes, and physical mixtures were determined at 70% relative humidity. Increases in weight (%) of the complexes were less than those of the physical mixtures, which demonstrates that hygroscopicity was reduced upon complexation with LDH due to the layer of LDH over the drugs.Key words layered double hydroxide; hygroscopicity; drug Layered double hydroxides (LDHs) have been used as matrices for drug delivery systems and as coating materials to protect compounds against external influences such as light and humidity.1-3) For example, complexation with LDH improved the thermostability of 5-fluorouracil.4) Additionally, LDH complexed with methotrexate, an anticancer drug, provided a lower IC 50 value compared to methotrexate alone because the LDH nanoparticles were internalized in cells via endocytosis, enhancing cellular uptake efficiency.5) Thus, LDHs have high biological affinity and low cytotoxicity. Hydrotalcite, which is used as an antacid, is a type of LDH with anionic-exchange properties. 6) LDH substances are composed of a positively charged brucite-like octahedral layer and an interlayer anion. 7,8) The brucite-like layer consists of octahedrons with 2 or 3 positively charged metal ions. Therefore, LDHs with different characteristics (e.g., varying charge density, interlayer anions, and particle size) can be synthesized at low cost. Compared to montmorillonite and smectite, the layer charge density of LDH is large, and the interaction between the LDH layer and the interlayer anion is strong. The interlayer distance (d) is the thickness of one layer plus the distance of the interlayer space. An increase in d indicates that the interlayer anions can be exchanged with other anions (i.e., intercalation). Three intercalation methods are effective for LDHs: ion exchange, reconstruction, and coprecipitation. 9) All of these methods usually involve reaction in aqueous solution where the ease of intercalation is influenced by the interlayer anion, in the order of I ) in the interlayer region. However, the carbonate ion is the most stable in the interlayer space due to its high affinity for the layer.10) Therefore, decarbonation of LDH-CO 3 has been considered difficult, and LDH-CO 3 has been transformed to calcined-LDH by heating in an oven at ...

Background Hereditary breast and ovarian cancer (HBOC) syndrome is a susceptibility syndrome for cancers, such as breast and ovarian cancer, and BRCA1/2 are its causative genes. Annual breast-enhanced magnetic resonance imaging (MRI) is recommended for BRCA1/2 mutation carriers aged over 25 years as a secondary prevention of breast cancer. However, breast MRI surveillance is rarely performed in Japan, and only four cases of breast cancer diagnosis triggered by MRI surveillance have been reported. Case presentation At our hospital, MRI triggered the diagnosis of breast cancer in four cancer-free BRCA1/2 mutation carriers. In one of our four cases, although MRI showed only a 3-mm focus, we could diagnose breast cancer by shortening the surveillance interval considering the patient’s high-risk for developing breast cancer. Conclusions Image-guided biopsy, including MRI-guided biopsy, depending on the size of the lesion, and shorter surveillance intervals are useful when there are potentially malignant findings on breast MRI surveillance for cancer-free patients with HBOC.

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