Читать книгу Oil-in-Water Nanosized Emulsions for Drug Delivery and Targeting - Tamilvanan Shunmugaperumal - Страница 40

Since many APIs of commercial interest generally have a solubility that is too low in FDA‐approved oils, Lance et al. (1995) proposed a method to incorporate such APIs into the interfacial o/w layer of the emulsion droplets. This can be achieved by initially dissolving the API along with the phospholipid (emulsifier) in an organic solvent, instead of in the oil.

Following the solvent evaporation, the obtained phospholipids/API co‐mixture is used in the de novo production of the emulsions (Davis and Washington 1988). However, this approach suffers from possible API nanocrystal formation and from the use of organic solvent during the emulsion preparation process. To overcome such drawbacks, a novel SolEmul^® technology was developed in which an additional high‐speed homogenization step is included to mix the API with emulsion. The API particles are micronized to the nanosize range prior to incorporation into the emulsions. By this technique, adequate amounts of lipophilic APIs can be substantially incorporated into the lipophilic core or intercalated between the selected emulsifier molecular films at the o/w interface of the emulsions. The APIs reported to have been incorporated by this novel approach are amphotericin B, carbamazepine, and itraconazole (Buttle et al. 2002; Müller and Schmidt 2002; Akkar and Müller 2003a, b). However, it should be emphasized that all the lipophilic API molecules that have been incorporated into the emulsions by SolEmul^® technology are meant only for parenteral use (Buttle et al. 2002; Müller and Schmidt 2002; Akkar and Müller 2003a, b) and so far no ocular, nasal, and topical active agents have been incorporated by this approach although there is no regulatory reason to exclude this technical improvement when designing emulsion formulations for these applications.

Figure 2.3. Schematic diagram for preparation of nanosized emulsion.