title: Complexation of oxethazaine with 2-hydroxypropyl-β-cyclodextrin: increased drug solubility, decreased cytotoxicity and analgesia at inflamed tissues.
abstract: OBJECTIVE
  Oxethazaine (OXZ) is one of the few local anaesthetics that provides analgesia at low pH, but presents poor solubility, cytotoxicity and no parenteral formulations. To address these issues, we aimed to prepare OXZ host-guest inclusion complex with hydroxypropyl-beta-cyclodextrin (HP-β-CD).
  
  
  METHODS
  The inclusion complex was formed by co-solubilization, followed by a job plot analysis to determine stoichiometry of complexation and dialysis equilibrium analysis (based on UV/VIS absorption and fluorescence profiles of OXZ). Complex formation was confirmed by phase-solubility data, X-ray, Scanning Electron Microscopy and DOSY-1H-NMR experiments. In vitro cytotoxicity was analysed by MTT test in 3T3 fibroblasts. In vivo analgesia was tested by Von Frey test (inflammatory wounds - rats).
  
  
  RESULTS
  Oxethazaine complexed (1 : 1 molar ratio) with HP-β-CD, as indicated by loss of OZX crystalline structure (X-ray) and strong host: guest interaction (NMR, K = 198/M), besides increased solubility. In vitro cell survival improved with the complex (IC50OXZ = 28.9 μm, OXZ : HP-β-CD = 57.8 μm). In addition, the complex (0.1% OXZ) promoted in vivo analgesia for the same time that 2% lidocaine/epinephrine did.
  
  
  CONCLUSIONS
  Our results show that complexation improved physicochemical and biological properties of OXZ, allowing its application to inflamed tissues by parenteral routes.
authors.affiliation: Biochemistry and Tissue Biology Department, Biology Institute, University of Campinas (Unicamp), Campinas, SP, Brazil.
authors.forename: Andressa R
authors.initials: AR
authors.lastname: Prado
authors.affiliation: Department Quantum Phenomena in Novel Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin, Germany.
authors.forename: Fabiano
authors.initials: F
authors.lastname: Yokaichiya
authors.affiliation: Institute for Energetic and Nuclear Research (IPEN)/Multipurpose Brazilian Reactor, Cidade Universitária Armando Salles de Oliveira, São Paulo, SP, Brazil.
authors.forename: Margareth Kazuyo Kobayashi Dias
authors.initials: MKKD
authors.lastname: Franco
authors.affiliation: Biochemistry and Tissue Biology Department, Biology Institute, University of Campinas (Unicamp), Campinas, SP, Brazil.
authors.forename: Camila Morais Gonçalves da
authors.initials: CMGD
authors.lastname: Silva
authors.affiliation: Biochemistry and Tissue Biology Department, Biology Institute, University of Campinas (Unicamp), Campinas, SP, Brazil.|Faculty of Pharmaceutical Sciences, University of Campinas (Unicamp), Campinas, SP, Brazil.
authors.forename: Laura
authors.initials: L
authors.lastname: Oliveira-Nascimento
authors.affiliation: Department of Physiological Sciences, Piracicaba Dental School, University of Campinas (Unicamp), Piracicaba, SP, Brazil.
authors.forename: Michelle
authors.initials: M
authors.lastname: Franz-Montan
authors.affiliation: Department of Physiological Sciences, Piracicaba Dental School, University of Campinas (Unicamp), Piracicaba, SP, Brazil.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Volpato
authors.affiliation: Technologic Federal University of Parana, Londrina, PR, Brazil.
authors.forename: Luís F
authors.initials: LF
authors.lastname: Cabeça
authors.affiliation: Biochemistry and Tissue Biology Department, Biology Institute, University of Campinas (Unicamp), Campinas, SP, Brazil.
authors.forename: Eneida
authors.initials: E
authors.lastname: de Paula
mesh_terms: D000073738:2-Hydroxypropyl-beta-cyclodextrin / Q000737:chemistry*; D000698:Analgesia / Q000379:methods; D000779:Anesthetics, Local / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D041702:BALB 3T3 Cells; D002152:Calorimetry, Differential Scanning / Q000379:methods; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002626:Chemistry, Pharmaceutical / Q000379:methods; D004339:Drug Compounding / Q000379:methods; D004983:Ethanolamines / Q000737:chemistry* / Q000494:pharmacology*; D007249:Inflammation / Q000188:drug therapy*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D051379:Mice; D008855:Microscopy, Electron, Scanning / Q000379:methods; D010146:Pain / Q000188:drug therapy; D059408:Pain Management / Q000379:methods; D051381:Rats; D017208:Rats, Wistar; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D000779:Anesthetics, Local; D004983:Ethanolamines; D000073738:2-Hydroxypropyl-beta-cyclodextrin; C100289:oxethazaine
keywords: bioassay approaches; dosage form design and characterization; pharmaceutical analysis; pharmaceutics and drug delivery