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Type: Artigo de periódico
Title: Physico-chemical Characterization Of Benzocaine-beta-cyclodextrin Inclusion Complexes.
Author: Pinto, Luciana M A
Fraceto, Leonardo Fernandes
Santana, Maria Helena A
Pertinhez, Thelma A
Junior, Sérgio Oyama
de Paula, Eneida
Abstract: Local anesthetics are able to induce pain relief by binding to the sodium channel of excitable membranes, blocking the influx of sodium ions and the propagation of the nervous impulse. Benzocaine (BZC) is a local anesthetic whose low water-solubility limits its application to topical formulations. The present work focuses on the characterization of inclusion complexes of BZC in beta-cyclodextrin (beta-CD). Differential scanning calorimetry and electron microscopy gave evidences of the formation and the morphology of the complex. Fluorescence spectroscopy showed a BZC/beta-CD 1:1 stoichiometry. Phase-solubility diagrams allowed the determination of the association constants between BZC and beta-CD (549 M(-1)) and revealed that a three-fold increase in BZC solubility can be reached upon complexation with beta-CD. The details of BZC/beta-CD molecular interaction were analyzed by 1H 2D NMR allowing the proposition of an inclusion model for BZC into beta-CD where the aromatic ring of the anesthetic is located near the head of the beta-CD cavity. Moreover, in preliminary toxicity studies, the complex seems to be less toxic than BZC alone, since it induced a decrease in the in vitro oxidation of human hemoglobin. These results suggest that the BZC/beta-CD complex represents an effective novel formulation to enhance BZC solubility in water, turning it promising for use outside its traditional application, i.e., in infiltrative anesthesia.
Subject: Anesthetics, Local
Biological Availability
Calorimetry, Differential Scanning
Chemistry, Physical
Drug Stability
In Vitro Techniques
Magnetic Resonance Spectroscopy
Microscopy, Electron, Scanning
Models, Molecular
Particle Size
Physicochemical Phenomena
Spectrometry, Fluorescence
Citation: Journal Of Pharmaceutical And Biomedical Analysis. v. 39, n. 5, p. 956-63, 2005-Oct.
Rights: fechado
Identifier DOI: 10.1016/j.jpba.2005.06.010
Date Issue: 2005
Appears in Collections:Unicamp - Artigos e Outros Documentos

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