Studies On The Intercalation Of A Chiral Pharmaceutical Agent L-dopa Into Mg/Al Layered Double Hydroxide And Its Properties As A "Molecular Container"

鈽匒 well-crystallized product, magnesium-aluminum layered double hydroxide (Mg/Al-LDH) with intercalated chiral pharmaceutical agent L-dopa (L-dopa LDH) has been obtained, and the supramolecular structure as well as its properties including thermal and optical stability of the intercalated L-dopa have been investigated. Therefore, this work demonstrates the novel approach improving thermal and optical stabilities of a chiral pharmaceutical with LDH as a "molecular container".鈽匧-dopa has been successfully intercalated into the host, Mg/Al-LDH, via twice successive ion-exchange processes from the nitrate form of hydrotalcite under nitrogen atmosphere and avoiding sunlight. The dependence of the intercalation process of L-dopa on preparation conditions such as pH value, ratio of guest and precursor, reaction time and route were investigated. The structure and composition of the intercalated material have been studied by XRD, UV-vis, FTIR, ¹³ C MNR, ICP, elemental analysis and thermogravimetric analysis, and a schematic model of the intercalated structure has been proposed. 鈽匜urthermore, the properties of this hybrid material as a "molecular container" for storing, transporting and releasing L-dopa have been investigated in detail, including its thermal and optical stability by means of TG/DTA, TG-MS, ¹³ C NMR and automatic polarimeter. It has been found that the thermolysis of L-dopa LDH was quite different from that of the pristine L-dopa, and the decrease of the specific optical rotation of the former on exposure to sunlight, UV light, or heat treatment due to partial racemization was far less than that of the latter, indicating that the thermal and optical stability of L-dopa were enhanced significantly after intercalation into sheets of LDHs. In addition, the in vitro drug release of this intercalation composite was measured by a dissolution test in a simulated intestinal fluid containing phosphates (buffer at pH 7．6 and 6．4 respectively). The results show that these drug-inorganic hybrid materials can be used as an effective drug delivery system.