title: Study of the complexation of risperidone and 9-hydroxyrisperidone with cyclodextrin hosts using affinity capillary electrophoresis and (1)H NMR spectroscopy.
abstract: The complexation of risperidone (Risp) and 9-hydroxyrisperidone (9-OH-Risp), atypical antipsychotics, with seven cyclodextrins (CDs) of pharmaceutical interest (native and hydroxypropylated (HP) alpha-, beta-, gamma-CDs and methyl (Me)-beta-CD) was studied by affinity capillary electrophoresis (ACE) and nuclear magnetic resonance spectroscopy (NMR) for acidic pH 2.5 and physiological pH 7.4. The 1:1 stoichiometry of the complexes was established by (1)H NMR spectroscopy using the continuous variation method developed by Job. The apparent binding constants of the 14 complexes at both pH were determined by ACE through the linear Scott's plots. The NMR spectroscopy investigation of the binding constants was achieved for the two CDs allowing the highest complexation: the beta-CD and Me-beta-CD. Both ACE and NMR spectroscopy studies provide similar conclusions by considering the influence of the 9-hydroxylation, the influence of the CD substitution and the influence of the pH. Moreover, the NMR spectroscopy results have allowed to suppose a pH-dependent inclusion mechanism. A thermodynamic study was then performed by ACE at both pH for the Risp.Me-beta-CD and 9-OH-Risp.Me-beta-CD complexes: the opposite signs of the entropic change (DeltaS degrees <0 at pH 2.5 and DeltaS degrees >0 at pH 7.4) confirms the influence of the pH on the complexation mechanism and the possible difference in the depth of the analyte inclusion in the hydrophobic cavity of the CD. Last, the two-dimensional ROESY (rotating-frame Overhauser spectroscopy) ((1)H-(1)H) and HOESY (heteronuclear Overhauser effect spectroscopy) ((19)F-(1)H) experiments have proved the inclusion of the aromatic part of the Risp and 9-OH-Risp in the hydrophobic CD cavity and lead us to propose a model of complexation.
authors.affiliation: Laboratoire de Chimie Analytique, EA 4034, Faculté des Sciences Pharmaceutiques et Biologiques, Université de Lille 2, 3 rue du Pr. Laguesse, B.P. 83, 59006 Lille Cédex, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Danel
authors.forename: Nathalie
authors.initials: N
authors.lastname: Azaroual
authors.forename: Albane
authors.initials: A
authors.lastname: Brunel
authors.forename: Damien
authors.initials: D
authors.lastname: Lannoy
authors.forename: Gaston
authors.initials: G
authors.lastname: Vermeersch
authors.forename: Pascal
authors.initials: P
authors.lastname: Odou
authors.forename: Claude
authors.initials: C
authors.lastname: Vaccher
mesh_terms: D014150:Antipsychotic Agents / Q000737:chemistry*; D003505:Cyclodextrins / Q000737:chemistry*; D019075:Electrophoresis, Capillary / Q000379:methods*; D007555:Isoxazoles / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015394:Molecular Structure; D000068882:Paliperidone Palmitate; D011743:Pyrimidines / Q000737:chemistry*; D018967:Risperidone / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D014150:Antipsychotic Agents; D003505:Cyclodextrins; D007555:Isoxazoles; D011743:Pyrimidines; D018967:Risperidone; D000068882:Paliperidone Palmitate