Biocompatibility and efficiency of drug-loaded P(3)HB-microspheres

The most promising drug delivery systems today are biodegradable microspheres and microcapsules. Microspheres can be injected subcutaneously or intramuscularly, adapted for oral administration or inhalation, and introduced into the bloodstream (Ueda 2003). The rapid development of microencapsulation has triggered an interest in biocompatible and biodegradable polyhydroxyalkanoates (PHAs), which can be processed in different physical states, by various methods. PHAs as materials for drug delivery systems have been investigated much less extensively than other biodegradable polymers, although they can successfully be used in constructing sustained drug delivery systems (Ammas 1998, Gürsel 2000). PHA microparticles have already been tested as carriers of antibiotics, hormones, and anticancer drugs. Researchers of the Institute of Biophysics of the Siberian Branch of the Russian Academy of Sciences have developed technologies of PHA synthesis, recovery, and purification to prepare high-purity polymers (Volova 2004). Specimens of these polymers were examined in comprehensive toxicological, medical, physiological, and histological investigations, which included experiments with cell cultures in vitro and with laboratory animals. High biological compatibility of PHAs and items from them was proved at the levels of cells, tissues, and organism. The tested PHAs can be safely used in medicine (Shishatskaya 2004 & 2005). Important aspects of developing drug delivery systems in the form of bioand blood-compatible microparticles are careful choice and in vivo investigation of the route of drug administration and studying of bioresorption of the matrix.