Emulsion nasal applications

It has been shown in a number of studies that the incorporation of drug in o/w nanosized emulsions significantly increased the absorption of the drug when compared with the equivalent aqueous solution administered orally [132-135], However, the use of emulsions for oral application is limited since other attractive alternatives, such as self-emulsifying oil delivery systems, which are much less sensitive and easy to manufacture, are available [136,137], Thus the potential of nanosized emulsions after administration with parenteral and traditional nonparenteral topical routes such as ocular, percutaneous, and nasal is covered in this section. 

Although encapsulation using the emulsion solvent removal methods has been investigated for applications in transdermal. - nasal,pulmonary,and ophthalmic drug delivery, - the vast majority of papers addressed the most common routes the oral and the parenteral, for the delivery of medications. 

Nasal drops and liquid nasal sprays are solutions, emulsions or suspensions intended for instillation or spraying into the nasal cavities. Nasal powders or nasal insufflation powders are intended for insufflation into the nasal cavity by means of a suitable device. The size of the particles are such as to localise their deposition in the nasal cavity. In nasal sticks and so-called inhalation ointments mostly volatile active substances are formulated in a fatty base. Nasal washes are generally aqueous iso-osmotic solutions intended to cleanse the nasal cavity. If they are intended for application on injured parts of the mucosa, or prior to a surgical operation, they have to be sterile. Nasal powders and nasal sticks are not very common in pharmacy practice. Therefore they are not discussed in this chapter. 

The use of ttaditional disperse systems, e.g., macroemulsions, in the pharmaceutical industry has been limited due to manufacturing complexity and stability problems [117]. The characteristic properties of nano-emulsions (kinetic stability, small and controlled droplet size, etc.) make them interesting systems for pharmaceutical applications. Indeed, nano-emulsions are used as drug delivery systems for administration through various systemic routes. There are numerous publications on nano-emulsions as drug delivery systems for parenteral [17,18,28,29,118-124], oral [25,125-129], and topical administration, which includes the administration of formulations to the external surfaces of the body skin [32,130,131] and to the body cavities nasal [30,132] as weU as ocular administration [31,133-136]. Moreover, many patents concerning pharmaceutical applications of nano-emulsions have been registered [17,18,25,137-145]. An application of nano-emulsions in this field has been in the development of vaccines [33,146-147]. 

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