Controlled drug release by the use of porous calcium silicate

• Published in: Drug Delivery System Vol. 10; no. 3; pp. 159 - 166
• Main Authors: Murakami, Teruo, Yata, Noboru
• Format: Journal Article
• Language: Japanese
• Published: THE JAPAN SOCIETY OF DRUG DELIVERY SYSTEM 10.05.1995
• Subjects: Fiorite® RE; implant use; oral use; porous calcium silicate; sustained release
• ISSN: 0913-5006; 1881-2732
• DOI: 10.2745/dds.10.159

Oral and implant preparations for controlled release of drugs were developed by the use of porous calcium silicate (Florite® RE(FLR), Eizai co.) as a drug carrier. Usefulness of the preparations was evaluated in in vitro and in vivo release studies, In oral preparation, sulfamethizole(SMZ) was used as a model compound. SMZ was incorporated into pores of FLR by grinding SMZ acetone solution with FLR. For controlling the release of SMZ, the pores were sealed off by adding different amounts of tristearin (TS) to SMZ-incorporating FLR. SMZ preparations sealed with TS administered orally at a dose of 20mg SMZ/kg in rabbits showed a remarkable sustained release of SMZ over 30 hrs, compared to SMZ powder(MRT : 10.5 vs 4.6hr). In implant preparations, FITC-dextrans with different molecular weights and human epidermal growth factor (hEGF) were used as model macromolecular compounds. The release of these compounds was controlled by sealing the pores with a mixture of TS and polyethylene glycol 6000 (PEG) at different weight ratios, where PEG was used as a water channel forming agent. Subcutaneously implanted FITC-dextran preparations at a dose of 10 μmol/kg showed a sustained release in rats over more than 1 month, although a small amount of burst release was observed in the early phase. A sustained and constant release in vivo was also observed in hEGF prepartion. Above results indicate that the release of relatively hydrophobic compounds, which can penetrate the intestinal mucosal membranes after oral administration, can be relatively easily controlled by changing the amount of TS for sealling of FLR pores, and the release of hydrophilic compounds for implant use can be controlled by mixing a water channel forming agent with TS after incorporating the drug into FLR pores.