A new nanovesicular system for nasal drug administration.

The goal of this work was to study the characteristics of a new phospholipid nanovesicular carrier for nasal administration of drugs. Multilamellar vesicles were visualized by electron microscopy, and their mean distribution size of 200 nm was evaluated by DLS. Measured pH and viscosity values were found adequate for a nasal delivery carrier. CLS micrographs of the nasal mucosa of rats following administration of the carrier incorporating probes with various properties show delivery into the nasal mucosa layers. Tramadol containing systems were characterized and tested for their analgesic effect in two pain animal models. In mice, a significantly higher antinociceptive effect and a rapid onset of action were obtained as compared to other nasal delivery carriers and to oral treatment. This enhanced analgesic effect was further confirmed in rat pain model and sustained by drug plasma and brain levels. To test the systems behavior in a larger animal, a pharmacokinetic crossover study was carried out in sheep after administrating Tramadol nasally in the nanocarrier and IV. The plasma and CSF absolute bioavailability values were 1.09 and 0.87, respectively. HPLC and LC-MS/MS methods for quantification of Tramadol in plasma, brain and CSF were developed and are presented here. It is noteworthy that no pathological alterations or inflammation signs were observed in rat nasal mucosa following sub-chronic treatment. The results obtained in this work encourage further investigation of using the new carrier for nasal delivery of drugs in humans.