Application of a Microreactor to Pharmaceutical Manufacturing: Preparation of Amorphous Curcumin Nanoparticles and Controlling the Crystallinity of Curcumin Nanoparticles by Ultrasonic Treatment.

Amorphous nanoparticles of curcumin (ANC) with primary particle sizes of 50 to 100 nm were prepared using a forced thin film reactor (FTFR). An ethanolic solution of curcumin and polyvinylpyrrolidone was mixed with purified water in an FTFR to precipitate the curcumin nanoparticles. In order to obtain amorphous particles, the solvent used and the operation conditions of FTFR such as the rotation speed of the disk and the flow rate of solutions were adjusted. According to powder X-ray diffraction (XRD) analysis and Fourier transform infrared spectroscopy (FT-IR), amorphous curcumin nanoparticles were obtained. To control the crystallinity, ultrasonic treatment was carried out on ANC suspended in water or hexane to which a polymer or a surfactant was added to prevent the growth of the particles. Transmission electron microscopy, XRD, and FT-IR analyses indicated that the treatment enabled the transformation of ANC to crystalline form 1 (a fundamental curcumin structure) and then to crystalline form 2 or crystalline form 3 without any change in the size of the primary particles. These findings suggest the possibility of preparing solid particles with a desired particle size and crystallinity.

The disposition and intestinal absorption of zinc in rats.

The variety of physiologic and biologic functions of zinc is expected to enable the development of zinc-related medicines. In this study, the distribution of endogenous zinc, the disposition after intravenous injection, and the intestinal absorption of zinc were investigated in vivo using rats from the viewpoints of pharmaceutical science and pharmacokinetics. High levels of endogenous zinc were observed in bone, testis, and liver. RT-PCR analysis on the mRNA of metallothionein in tissues clarified that it is significantly correlated with the distribution of zinc, suggesting that zinc is accumulated in tissues as a complex with MT. Following intravenous injection, uptake of zinc was high in liver, spleen, pancreas, kidney, and intestine. Fractional absorptions of zinc after oral administration to fasted rats were greater than those to fed rats, suggesting that some factors in diet inhibit the absorption of zinc. In fasted rats, fractional absorption was slightly decreased in high-dose group, suggesting the involvement of carrier-mediated transport. Study utilizing an in situ closed-loop method also indicated saturable intestinal absorption of zinc. These findings will further the research and development of zinc-related medicines by providing basic and important information on zinc.