Investigation on Synthesis, Characterization, and In Vitro Release of Captopril-Intercalated Layered

• 作 者: Hui Zhang Kang Zou Shaohuan Guo Xue Duan
• 机 构: Ministry of Education Key Laboratory of Science and Technology of Controllable Chemical Reactions, B
• 出 处: 2005 WHTS3rd Annual Congress of International Drug Discovery
• 发表日期: 2005年12期

　　Captopril (here abbreviated as Cpl), 1-[(2S)-3-mercaptp-2-methyl-1-oxypropyl]-L-proline (CgH15NO3S), an angiotensin converting enzyme inhibitor, has been successfully intercalated into magnesium aluminum layered double hydroxides (denoted as Cpl-LDHs) by coprecipitation assembly technique.The X-ray diffraction spectra indicate that the reflections of Cpl-LDHs are sharp and symmetric, demonstrating the well-defined and single phase structure of LDHs-like compounds.The basal spacing d003 value was greatly expanded from 0.88 nm for NO3-containing LDHs to 1.42 nm for Cpl-LDHs,indicating the successful intercalation of Cpl between the host LDHs layers.The FT-IR spectrum of Cpl-LDHs shows that two bands at 1577 and 1402 cm-1 due to the antisymmetric and symmetric stretching mode of-CO2-, respectively,shift to lower wavenumbers, compared with free CO2-in Cpl (1748 and 1473 cm-1).It is suggested that the interlayer Cpl involves hydrogen bonding between-CO2-and hydroxyl group of LDHs layers [1].Based on ICP elemental analysis, the percentage of Cpl in LDHs is ca.31%.The in vitro release evaluation displays that the release rate and release percentages decrease obviously with increasing buffer pH.At pH 1.25, the release rate is very fast with ca.100% in 10 min.At pH 4.6, the release of Cpl is also fast during the first 1 min (65%), thereafter, a slower release is observed (95% after 55 min).At pH 7.4, 95% of Cpl released is not reached until to 100 min release time.The XRD, FT-IR, and ICP analyses for residues recovered from release media suggest that the release process may undergo gradual transition from dissolution mechanism to ion exchange one due to the increase in pH values of release media.