title: Effect of geometrical structure on drug release rate of a three-dimensionally perforated porous apatite/collagen composite cement.
abstract: To improve the biocompatibility, inter-connective pore structure, and drug delivery ability of self-setting apatite/collagen composite cement (ACC), a three-dimensionally perforated porous apatite/collagen composite cement (TPPACC) containing 3% indomethacin (IMC) was obtained in an arranged multi-cross with 20, 40, and 60 stainless steel needlelike male dies, and stored and hardened at 37 degrees C and 100% relative humidity for 24 h. The mean radius of micro-pores of the TPPACC was evaluated to be 0.125 microm by mercury porosimetry. X-ray powder diffraction and FT-IR spectroscopy suggested that TPPACC consisted of carbonated apatite and had a structure similar to that of natural rat bone. The IMC release rates from a TPPACC block containing the drug were measured in simulated body fluid. The rate of release increased with the number of macro-pores that from planar surface matrix systems followed the Higuchi equation. The relationship between the Higuchi constant and surface area of TPPACC showed a straight line with K = 0.2123 and R(2) = 0.9892. These results indicated that the rate of drug release from TPPACC could be controlled by the number of macro-pores for bone cells.
authors.affiliation: Research Institute of Pharmaceutical Sciences, Faculty of Pharmacy, Musashino University, Shinmachi 1-1-20, Nishi-Tokyo 202-8585, Japan. motsuka@musashino-u.ac.jp
authors.forename: Makoto
authors.initials: M
authors.lastname: Otsuka
authors.forename: Hidenori
authors.initials: H
authors.lastname: Nakagawa
authors.forename: Atsuo
authors.initials: A
authors.lastname: Ito
authors.forename: William I
authors.initials: WI
authors.lastname: Higuchi
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics; D001672:Biocompatible Materials / Q000737:chemistry*; D001843:Bone Cements / Q000737:chemistry*; D055598:Chemical Phenomena; D003094:Collagen / Q000737:chemistry*; D016503:Drug Delivery Systems; D006882:Hydroxyapatites / Q000737:chemistry*; D008422:Materials Testing; D016062:Porosity; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D001672:Biocompatible Materials; D001843:Bone Cements; D006882:Hydroxyapatites; D003094:Collagen