PERORAL ADMINISTRATION OF NANOPARTICLES

Nanoparticles are colloidal polymeric drug carriers that hold promise for peroral drug delivery. Nanoparticles are retained in the gut of rats and mice in small quantities for substantial time periods (up to 6 days). In addition, they are taken up in particulate form in the intestine and appear in the lymph nodes, blood, liver, spleen, and in sites of inflammation in the body. Three possibilities in the mechanism of uptake are discussed: (1) intracellular uptake; (2) intercellular/paracellular uptake; and (3) uptake via the M-cells and Peyer's patches in the gut. The uptake is size-dependent; smaller particles are taken up to a higher degree than larger particles. Nevertheless, the gastrointestinal uptake of intact particles up to the size of starch particles has been reported as a very rare event. Binding to nanoparticles enhanced the peroral bioavailability of a number of drugs, and a significantly enhanced and prolonged pharmacological activity by binding to nanoparticles was reported for insulin and hydrocortisone.