title: Molecular complex consisting of two typical external medicines: intermolecular interaction between indomethacin and lidocaine.
abstract: The molecular complex formed between indomethacin (IDM) and lidocaine (LDC), which are typical external medicines, was studied. A thermal analysis, microscopic study and phase solubility technique suggested intermolecular interaction between IDM and LDC. The phase solubility profiles with IDM and LDC were classified as A(L)-type, indicating the formation of a 1 : 1 stoichiometric molecular complex. The apparent stability constant (K(S)), calculated from the slope and the intercept, was 4478.9 M(-1). A molecular ion peak was detected at 592.2 (m/z) from fast-atom bombardment-MS measurements, which was in accordance with the sum of the molecular weight for IDM (M(W): 357.81) and LDC (M(W): 234.38). The changes of IR spectra in the C=O stretching region showed that each intact hydrogen bond network was collapsed in the IDM-LDC system and strong interaction between IDM and LDC formed after their kneading. From the (1)H-NMR analyses, it was estimated that the dominant interactive site was the IDM carboxylic acid group which associated with the LDC diethyl amino group non-covalently.
authors.affiliation: Department of Pharmacy, Nihon University, Itabashi Hospital, 30-1 Ohyaguchi, Tokyo 173-8610, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Umeda
authors.forename: Toshiro
authors.initials: T
authors.lastname: Fukami
authors.forename: Takayuki
authors.initials: T
authors.lastname: Furuishi
authors.forename: Toyofumi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Mizue
authors.initials: M
authors.lastname: Makimura
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tomono
mesh_terms: D000779:Anesthetics, Local / Q000737:chemistry*; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D007213:Indomethacin / Q000737:chemistry*; D008012:Lidocaine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008859:Microscopy, Polarization; D008958:Models, Molecular; D012995:Solubility; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013055:Spectrophotometry, Infrared; D017550:Spectroscopy, Fourier Transform Infrared; D013818:Thermogravimetry
chemical_list: D000779:Anesthetics, Local; D000894:Anti-Inflammatory Agents, Non-Steroidal; D008012:Lidocaine; D007213:Indomethacin