“…Polymeric microparticles are widely studied in the pharmaceutical field for the purpose, among others, of obtaining better results in the oral administration of drugs by the production of multiple-unit drug delivery systems (Kawashima et al, 1993;Lin and Kao, 1991). These systems have several advantages, such as (Kawashima et al, 1993;Lin and Kao, 1991;Murilo et al, 2002) ready distribution over a large surface area, more constant drug plasma levels, higher accuracy in reproducibility dose by dose, no negative impact on bioavailability, lower risk of toxicity due to dose dumping, gastrointestinal tract protection from drug toxicity, labile drug protection from degradation in the gastrointestinal tract and antigen delivery to the Peyer's patches for oral immunization.…”