title: Freeze-drying of emulsified systems: A review.
abstract: Colloidal systems such as emulsions, microemulsions and nanoemulsions are able to transport active molecules, enhance their solubility and stability and minimize their side effects. However, since they are dispersions with an aqueous continuous phase they have some disadvantages such as the risk of microbiological contamination, degradation by hydrolysis, physico-chemical instability and loss of pharmacological activity of the drug. Freeze drying, in which the water is removed from the preparation by sublimation under vacuum, has been suggested as a means to resolve these problems. Lyophilized products are very stable and are easy to transport and store. However, there is very little information in the literature about the application of this technique to emulsified systems. The aim of this review is to evaluate the lyophilization process as a tool for increasing the shelf life of emulsified systems such as emulsions, microemulsions and nanoemulsions. In addition, the mechanism of cryoprotection and the techniques that can be used to characterize the freeze-dried systems are discussed.
authors.affiliation: Universidade Federal do Rio Grande do Norte (UFRN), Programa de Pós-graduação em Nanotecnologia Farmacêutica, Rua Gustavo Cordeiro de Farias, SN. Petrópolis, CEP: 59012-570 Natal/RN, Brazil; UFRN, Laboratório de Sistemas Dispersos (LASID), Rua Gustavo Cordeiro de Farias, SN. Petrópolis, CEP: 59012-570 Natal/RN, Brazil; Université Paris-Sud, Institut Galien Paris-Sud, UMR-CNRS 8612, 5, Rue Jean-Baptiste Clément, 92296 Châtenay-Malabry cedex, France.
authors.forename: Andreza Rochelle do Vale
authors.initials: AR
authors.lastname: Morais
authors.affiliation: Universidade Federal do Rio Grande do Norte (UFRN), Programa de Pós-graduação em Nanotecnologia Farmacêutica, Rua Gustavo Cordeiro de Farias, SN. Petrópolis, CEP: 59012-570 Natal/RN, Brazil; UFRN, Laboratório de Sistemas Dispersos (LASID), Rua Gustavo Cordeiro de Farias, SN. Petrópolis, CEP: 59012-570 Natal/RN, Brazil.
authors.forename: Éverton do Nascimento
authors.initials: Édo N
authors.lastname: Alencar
authors.affiliation: UFRN, Laboratório de Sistemas Dispersos (LASID), Rua Gustavo Cordeiro de Farias, SN. Petrópolis, CEP: 59012-570 Natal/RN, Brazil; Université Paris-Sud, Institut Galien Paris-Sud, UMR-CNRS 8612, 5, Rue Jean-Baptiste Clément, 92296 Châtenay-Malabry cedex, France.
authors.forename: Francisco Humberto
authors.initials: FH
authors.lastname: Xavier Júnior
authors.affiliation: UFRN, Laboratório de Sistemas Dispersos (LASID), Rua Gustavo Cordeiro de Farias, SN. Petrópolis, CEP: 59012-570 Natal/RN, Brazil.
authors.forename: Christian Melo
authors.initials: CM
authors.lastname: de Oliveira
authors.affiliation: UFRN, Laboratório de Sistemas Dispersos (LASID), Rua Gustavo Cordeiro de Farias, SN. Petrópolis, CEP: 59012-570 Natal/RN, Brazil; Université Paris-Sud, Institut Galien Paris-Sud, UMR-CNRS 8612, 5, Rue Jean-Baptiste Clément, 92296 Châtenay-Malabry cedex, France.
authors.forename: Henrique Rodrigues
authors.initials: HR
authors.lastname: Marcelino
authors.affiliation: Université Paris-Sud, Institut Galien Paris-Sud, UMR-CNRS 8612, 5, Rue Jean-Baptiste Clément, 92296 Châtenay-Malabry cedex, France.
authors.forename: Gillian
authors.initials: G
authors.lastname: Barratt
authors.affiliation: University Lyon, University Lyon-1, CNRS, LAGEP, CPE-Lyon, 43, Boulevard du 11 Novembre 1918, 69622 Villeurbanne cedex, France.
authors.forename: Hatem
authors.initials: H
authors.lastname: Fessi
authors.affiliation: Universidade Federal do Rio Grande do Norte (UFRN), Programa de Pós-graduação em Nanotecnologia Farmacêutica, Rua Gustavo Cordeiro de Farias, SN. Petrópolis, CEP: 59012-570 Natal/RN, Brazil; UFRN, Laboratório de Sistemas Dispersos (LASID), Rua Gustavo Cordeiro de Farias, SN. Petrópolis, CEP: 59012-570 Natal/RN, Brazil.
authors.forename: Eryvaldo Sócrates Tabosa
authors.initials: ES
authors.lastname: do Egito
authors.affiliation: University Lyon, University Lyon-1, CNRS, LAGEP, CPE-Lyon, 43, Boulevard du 11 Novembre 1918, 69622 Villeurbanne cedex, France. Electronic address: elaissari@lagep.univ-lyon1.fr.
authors.forename: Abdelhamid
authors.initials: A
authors.lastname: Elaissari
mesh_terms: D003451:Cryoprotective Agents / Q000737:chemistry; D004355:Drug Stability; D004655:Emulsions / Q000737:chemistry*; D005612:Freeze Drying
chemical_list: D003451:Cryoprotective Agents; D004655:Emulsions
keywords: Cryoprotectant; Drug delivery systems; Emulsion; Microemulsion; Nanoemulsion