Multiphase encapsulation system

Other new processes have involved modifications of the solvent evaporation method. To produce a more homogeneous emulsion and stabilize the protein, surfactants have been added to the protein phase. For example, researchers have claimed that the addition of hydrophobic ion pairs to the protein phase allows a more homogeneous mixture of the protein in the polymer phase and provides stabilization of the protein (M. C. Manning, personal communication, 1994). Reversed micelles (sucrose esters of fatty acids) stabilize ultrafine emulsions of the protein in the polymer phase and provide stabilization ofthe protein (Hayashi et al, 1994). In addition, the use of a multiphase encapsulation system may protect the protein from denaturation. One t q)e of multiphase system involves the suspension of... 

In multiphase filled polymer compositions, which may contain mixed filler types, combinations of fillers and fibres, or proportions of filler and a secondary modifying polymer, such as an elastomer, the spacial distribution of the phases has a direct bearing on the properties of the composite. In the case of the last mentioned system, the rubber may encapsulate the filler, be present as discrete droplets within the thermoplastic matrix or co-exist in both structural forms [80,81]. 

Due to the well-known enzymatic lability or environmental sensitivity of proteins, a common characteristic among protein delivery systems is the ability to protect the protein from the external environment. Modes of protection may be chemical or physical. A well-recognized system that provides physical protection of proteins is microcapsules, in which a solid membrane separates the solid contents of the microcapsule from the external environment. An alternative approach would be to replace a solid membrane with a liquid membrane, i.e., multiphase or multiple emulsions. Multiple emulsions may be prepared as either oil-in-water-in-oil (OAV/0) or water-in-oil-in-water (W/OAV) systems. Multiple-emulsion systems, for the purpose of delivering proteins, would be comprised of an interior aqueous phase, containing the water-soluble protein, separated from the external aqueous phase by an oil phase, i.e., W/OAV emulsions (Fig. 1). Multiple emulsions, therefore, provide an alternative technique for the encapsulation of proteins and other materials that would otherwise be metabolized, rapidly cleared, or toxic to the patient. Multiple emulsions have been utilized for parenteral and oral administration (Brodin et al, 1978). Although there is a physical resemblance to microcapsules, multiple... 

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