Issues in oral nanoparticle drug carrier uptake and targeting.

Some of the broader issues relating to the exploration of the use of nanoparticulate drug carriers by the oral route to achieve absorption of molecules which are poorly absorbed from the gastrointestinal tract are considered briefly here. These relate to both the pharmaceutical and biological characteristics of the carrier and carrier-gut interactions, the dynamic nature of such interactions, the varied modes of uptake, and the difficulties in targeting to the gut epithelium to encourage more efficient uptake of nanoparticles. These have the unhelpful habit of aggregating and flocculating hence increasing their effective size, when small size aids uptake and translocation. Post-absorption events can be equally hazardous and need further research. The question is asked whether or not it is wise load the gut lumen with molecules such as insulin even when protected in a carrier, and the suggestion is made that targets need to be rethought. The epithelium of the gut and the lymphoid tissue itself offers much scope for therapeutic interventions through nanoparticle delivery.