Freeze-drying of emulsified systems: A review.

Authors :: Morais AR
Alencar Édo N
Xavier Júnior FH
de Oliveira CM
Marcelino HR
Barratt G
Fessi H
do Egito ES
Elaissari A
Source :: International journal of pharmaceutics [Int J Pharm] 2016 Apr 30; Vol. 503 (1-2), pp. 102-14. Date of Electronic Publication: 2016 Mar 02.
Publication Year :: 2016
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.<br /> (Copyright © 2016 Elsevier B.V. All rights reserved.)