Hirotaka Honda

Preparation of monolayer particle coated powder by the dry impact blending process utilizing mechanochemical treatment

Abstract Spherical silica particles 0.3, 0.6 and 0.9 μm in diameter, and spherical polyethylene particles 5.2 and 11.9 μm in diameter were used as coating and core materials respectively. Scanning electron microscopy revealed that the silica particles were fixed on the surface of the polyethylene particles, and a monolayer particle coated powder was formed by a dry impact blending preparation method when the ratios of the coating and core particle sizes were 0.3/11.9, 0.6/11.9, 0.9/11.9 and 0.3/5.2. In the dry impact blending of a binary powder mixture which contains two different sizes, it was shown that the ratio of the core and coating particle sizes, the particle sizes themselves and the action of impulsive forces during the operation were important factors in the effective preparation of the monolayer particle coated powder. The binding energies were calculated on the assumption that the Coulomb and London—van der Waals interactions were the basis of adhesion for these monolayer particle coated polyethylene powders. Consequently, it was found that the Coulomb interaction between particles with different electric charges was not always advantageous for the formation of the monolayer particle coated powder.

Preparation of Drug-Diluent Hybrid Powders by Dry Processing

New hybrid powders have been produced by the dry processing of six drugs (oxyphenbutazone, prednisolone, theophylline, indomethacin, phenacetin and aspirin), with potato starch used as a core material, by means of an electric mortar and a powder suface reforming system designed to produce hybrid powders. The hybrid powders obtained immediately after production differed in their structure from interactive mixtures. With the hybrid powders the drug was spread on the surface of the core particle by friction and collision that occurred in the dry process, but with interactive mixtures the drug simply adhered as intact particles to the surface of diluent particles. Scanning electron microscopy and powder X‐ray diffractometry indicated that the mechanochemical phenomenon was essential for the production of the hybrid powders. With time, a shape change in the adhering drug was observed as a relaxation process took place, with recrystallization resulting from the release of accumulated energy. The change with time might depend upon the method of producing powders and the physical properties of the drug used, e.g. the smooth layer of indomethacin produced by the powder surface reforming system reverted to fine particles tightly adhering to the starch surface, though no change was observed with prednisolone.

Drug dissolution from indomethacin-starch hybrid powders prepared by the dry impact blending method

Abstract— Indomethacin was hybridized with potato starch using a dry impact blending method. Resultant hybrid powders were investigated by scanning electron microscopy and X‐ray powder diffraction. Amorphous indomethacin spread over the starch surface in a layer immediately after being hybridized, and then gradually reverted to fine crystalline particles adhering firmly to the starch surface. Indomethacin dissolution from the hybrid powder was compared with those from physical mixtures and granules taken from a commercially available capsule. Indomethacin dissolution from powder and capsule dosage forms, even in an acidic medium, was drastically accelerated by the hybridization.

Application of non-porous silica ultramicrospheres to high-performance liquid chromatographic column packings

Abstract Silica-composite particles were made from silica ultramicrospheres and polyethylene microspheres by a dry impact blending method for application as high-performance liquid chromatographic column packings. A column packed with silica-composite particles has a double packing structure, which consists of the spatial configuration of silica-composite particles in the column and a dense arrangement of silica on the polyethylene microsphere surfaces. This structure enables silica ultramicrospheres to be utilized as the stationary phase while simultaneously maintaining the flow of the mobile phase. Proteins with MW from 6500 to 669 000 were separated satisfactorily on a column packed withn-octadecyldimethylchlorosilane-coated silica-composite particles.

Utilization of the dry impact blending method to prepare irregularly shaped particles for high-performance liquid chromatographic column packings

Abstract The use of the dry impact blending method to prepare various materials for HPLC column packings that might otherwise be unsuitable is proposed. Crystalline hydroxyapatite (HA) was adopted as a model of a useful but fragile, irregularly shaped material and was embedded on the surface of polyethylene beads by impact blending. The resulting HA composites were evaluated for the crystallinity of the HA, the ability to adsorb and desorb proteins and performance as an HPLC column packing for proteins. Non-specific irreversible adsorption of proteins was observed. This adsorption could be saturated, however, and subsequently the HA composites performed satisfactorily in the HPLC of proteins.

Double-layered composite particles as a complex stationary phase for high-performance liquid chromatography

A composite particle with a double-coating layer consisting of silica (0.3 μm), titania (0.017 μm) and polyethylene beads (13.1 μm) was prepared by a dry impact blending method. The composite particle was employed as a complex stationary phase for high-performance liquid chromatography. Forming the surface double layer caused a change in the surface acidity of the oxides; as a result, the complex stationary phase enhanced the chromatographic retention behavior depending on the ionic interaction. Therefore, the complex stationary phase demonstrates the properties of a novel stationary phase rather than those of a mixture of two stationary phases. By using the multiple retention mechanisms, the separation of some basic drugs and the simultaneous analysis of acids and bases were performed.

Properties of cattle bone powder-coated composite particles as high-performance and open column liquid chromatographic column packings

Cattle bone powder (CBP) from natural resources was employed as a protein adsorbent instead of chemically synthesized hydroxyapatite (HA). Though a small amount of impurities was detected, CBP possessed a crystallinity similar to HA. Using CBP/40PE prepared from CBP and polyethylene beads (40 microns) by dry impact blending as an HPLC column packing, considerable correlation was observed between the elution concentrations of proteins and their pI. Such behavior was caused by the relatively large adsorption capacity for basic proteins. CBP/40PE could completely separate gamma-globulin from BSA also as an open column chromatographic support, under relatively low concentration.