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In principle, the lipophilic API molecules (thermostable) should however be incorporated by a de novo process as described earlier. Thus, the API is initially solubilized or dispersed together with an emulsifier in suitable single‐oil or oil mixture by means of heating. The water phase containing the osmotic agent with or without an additional emulsifier is also heated and mixed with the oil phase by means of high‐speed mixers. Further homogenization takes place to obtain the needed small droplet size range of the emulsion. A terminal sterilization by filtration, or steam, then follows. The emulsion thus formed contains most of the API molecules within its oil phase or its oil–water interface. This is a generally accepted and standard method to prepare lipophilic API‐loaded nanosized emulsions for parenteral, ocular, percutaneous, and nasal uses, as illustrated in Fig. 2.3. This process is normally carried out under aseptic conditions and nitrogen or argon atmosphere to prevent both contamination and potential oxidation of sensitive excipients.