Nanoparticles and microparticles for drug and vaccine delivery.

Nanoparticles are polymeric particles in the nanometer size range whereas microparticles are particles in the micrometre size range. Both types of particle are used as drug carriers into which drugs or antigens may be incorporated in the form of solid solutions or solid dispersions or onto which these materials may be absorbed or chemically bound. These particles have been shown to enhance the delivery of certain drugs across a number of natural and artificial membranes. In addition, the particles were shown to accumulate in areas of the intestine that appear to be the Peyer's patches. Possibly because of the combination of both effects these particles were able to significantly improve the bioavailability of some drugs after peroral administration in comparison with solutions. Recently nanoparticles coated with polysorbate 80 enabled the passage of small peptides and other drugs across the blood-brain barrier and the exhibition of a pharmacological effect after intravenous injection. Without the use of this type of nanoparticles the drugs did not cross this barrier and yielded no effect.